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How Does Captivity Affect Wild Animals?

Most experts agree it depends on the species, but much evidence shows large mammals suffer under even the best human care..

For much of the past year and a half, many of us felt like captives. Confined mostly within monotonous walls, unable to act out our full range of natural behavior, we suffered from stress and anxiety on a massive scale. In other words, says Bob Jacobs, a neuroscientist at Colorado College, the pandemic gave us a brief taste of life as lived by many animals.

Though anthropomorphism is always suspect, Jacobs observes that “some humans were quite frustrated by all that.” This is no surprise — we understand the strain of captivity as we experience it. But how do animals fare under the same circumstances? Putting aside the billions of domesticated livestock around the world, some 800,000 wild or captive-born animals reside in accredited American zoos and aquariums alone . Many people cherish these institutions, many abhor them. All want to know: Are the creatures inside happy?

Signs of Stress

Happiness is hard to judge empirically, but scientists do attempt to quantify welfare by measuring chronic stress, which can arise as a result of restricted movement, contact with humans and many other factors. The condition reveals itself through high concentrations of stress hormones in an animal's blood. These hormones, called glucocorticoids, have been correlated with everything from hair loss in polar bears to reproductive failure in black rhinos .

That said, it’s difficult to say what a normal level of stress is for any given animal. An obvious baseline is the captive’s wild counterpart (which surely has its own troubles, from predation to starvation). But the problem, says Michael Romero, a biologist at Tufts University, “is that there’s just not enough data.” Given the challenge of measuring a wild animal’s stress — the requisite capture isn’t exactly calming — few such studies have been undertaken, especially on large animals.

Besides, hormones may be an imperfect gauge of how agitated an animal really feels. “Stress is so complicated,” Romero says. “It’s not as well characterized as people think.” So researchers can also look for its more visible side effects. Chronic stress weakens the immune system, for example, leading to higher disease rates in many animals. Opportunistic fungal infections are the leading cause of death in captive Humboldt penguins , and perhaps 40 percent of captive African elephants suffer from obesity, which in turn increases their risk of heart disease and arthritis.

Another sign of stress is decline in reproduction, which explains why it’s often difficult to get animals to breed in captivity. Libido and fertility plummet in cheetahs and white rhinos, to name two. (A related phenomenon may exist in humans, Romero notes: Some research suggests that stress, anxiety and depression can reduce fertility. )

Even when breeding does succeed, high infant mortality rates plague some species, and many animals that reach adulthood die far younger than they would in the wild. The trend is especially poignant in orcas — according to one study , they survive just 12 years on average in American zoos; males in the wild typically live 30 years, and females 50.

Big Brains, Big Needs

Our wild charges don’t all suffer so greatly. Even in the above species there seems to be some variability among individuals, and others seem quite comfortable in human custody. “Captive animals are often healthier, longer-lived and more fecund,” writes Georgia Mason , a behavioral biologist at the University of Ontario. “But for some species the opposite is true.”

Romero emphasized the same point in a 2019 paper : the effect of captivity is, ultimately, “highly species-specific.” In many ways it depends on the complexity of each species’ brain and social structure. One decent rule of thumb is that the larger the animal, the worse it will adjust to captivity. Thus the elephant and the cetacean (whales, dolphins and porpoises) have become the poster children of the welfare movement for zoo animals.

Jacobs, who studies the brains of elephants, cetaceans and other large mammals, has described the caging of these creatures as a form of “ neural cruelty .” He admits they are “not the easiest to study at the neural level” — you can’t cram a pachyderm into an MRI machine. But he isn’t bothered by this dearth of data. In its absence, he holds up evolutionary continuity: the idea that humans share certain basic features, to some degree, with all living organisms. “We accept that there’s a parallel between a dolphin’s flipper and the human hand, or the elephant’s foot and a primate’s foot,” Jacobs says.

Likewise, if the brain structures that control stress in humans bear a deep resemblance to the same structures in zoo chimps — or elephants, or dolphins — then it stands to reason that the neurological response to captivity in those animals will be somewhat the same as our own. That, Jacobs says, is borne out by a half century of research into how impoverished environments alter the brains of species as varied as rats and primates.

Abnormal Behavior

Not all forms of captivity are equally impoverished, of course. Zookeepers often talk about “enrichment.” Besides meeting an animal’s basic material needs, they strive to make its enclosure engaging, to give it the space it needs to carry out its natural routines. Today’s American zoos generally represent a vast improvement over those of yesteryear. But animal advocates contend they will always fall short of at least the large animals’ needs. “No matter what zoos do,” Jacobs says, “they can’t provide them with an adequate, stimulating natural environment.”

If there is any doubt as to a captive animal’s wellbeing, even the uninformed zoogoer can detect what are perhaps the best clues: stereotypies. These repetitive, purposeless movements and sounds are the hallmark of a stressed animal. Elephants sway from side to side, orcas grind their teeth to pulp against concrete walls. Big cats and bears pace back and forth along the boundaries of their enclosures. One survey found that 80 percent of giraffes and okapis exhibit at least one stereotypic behavior. “Stress might be hard to measure,” Jacobs says, “but stereotypies are not hard to measure.”

Proponents are quick to point out that zoos convert people into conservationists, and occasionally reintroduce endangered species to the wild (though critics question how effective they truly are on these fronts). Considering their potential to bolster the broader conservation movement, Romero suggests an ethical calculation might be in order. “Maybe sacrificing a few animals’ health is worth it,” he says.

Wherever these moral arguments lead, Jacobs argues that “the evidence is becoming overwhelming” — large mammals, or at least many of them, cannot prosper in confinement. The environmental writer Emma Marris concludes the same in Wild Souls: Freedom and Flourishing in the Non-Human World . “In many modern zoos, animals are well cared for, healthy and probably, for many species, content,” she writes, adding that zookeepers are not “mustache-twirling villains.” Nevertheless, by endlessly rocking and bobbing, by gnawing on bars and pulling their hair, “many animals clearly show us that they do not enjoy captivity.”

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Should Animals be Kept in Captivity: an Ethical Dillema

Table of contents, benefits of captivity: conservation and education, ethical considerations: animal welfare and natural behavior, alternatives to captivity: ethical conservation, striking a balance.

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Griffin, D. R. (2001). Animal minds: Beyond cognition to consciousness. University of Chicago Press.
Kellert, S. R., & Wilson, E. O. (Eds.). (1993). The biophilia hypothesis. Island Press.
Lindemann-Matthies, P., & Bose, E. (2008). How many species are there? Public understanding and awareness of biodiversity in Switzerland. Human Ecology, 36(5), 731-742.

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Article Contents

Introduction, debating the moral standing of animals and the environment, the ethical complexity of zoo and aquarium conservation, rapid global change and the evolving ethics of ex situ research, conclusions, acknowledgments.

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Ecological Ethics in Captivity: Balancing Values and Responsibilities in Zoo and Aquarium Research under Rapid Global Change

Ben A. Minteer, PhD, is the Maytag Professor in the Center for Biology and Society and School of Life Sciences at Arizona State University in Tempe, Arizona. James P. Collins, PhD, is the Virginia M. Ullman Professor of Natural History and the Environment, School of Life Sciences, Arizona State University in Tempe, Arizona.

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Ben A. Minteer, James P. Collins, Ecological Ethics in Captivity: Balancing Values and Responsibilities in Zoo and Aquarium Research under Rapid Global Change, ILAR Journal , Volume 54, Issue 1, 2013, Pages 41–51, https://doi.org/10.1093/ilar/ilt009

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Ethical obligations to animals in conservation research and management are manifold and often conflicting. Animal welfare concerns often clash with the ethical imperative to understand and conserve a population or ecosystem through research and management intervention. The accelerating pace and impact of global environmental change, especially climate change, complicates our understanding of these obligations. One example is the blurring of the distinction between ex situ (zoo- and aquarium-based) conservation and in situ (field-based) approaches as zoos and aquariums become more active in field conservation work and as researchers and managers consider more intensive interventions in wild populations and ecosystems to meet key conservation goals. These shifts, in turn, have consequences for our traditional understanding of the ethics of wildlife research and management, including our relative weighting of animal welfare and conservation commitments across rapidly evolving ex situ and in situ contexts. Although this changing landscape in many ways supports the increased use of captive wildlife in conservation-relevant research, it raises significant ethical concerns about human intervention in populations and ecosystems, including the proper role of zoos and aquariums as centers for animal research and conservation in the coming decades. Working through these concerns requires a pragmatic approach to ethical analysis, one that is able to make trade-offs among the many goods at stake (e.g., animal welfare, species viability, and ecological integrity) as we strive to protect species from further decline and extinction in this century.

Responsibilities to wildlife in field research and conservation projects have always been complicated because ethical duties to animals, populations, and ecosystems can pull wildlife scientists and managers in different directions ( Minteer and Collins 2005a , 2005b , 2008 ). In recent years, this situation has been made even more complex by the impacts of global change (especially climate change), which, in many quarters, has forced a reassessment of research practice and conservation policy. Scientists and managers wrestle with understanding and protecting species and ecosystems in a rapidly changing environment ( Hannah 2012 ; Marris 2011 ). In parallel, conservation ethics and values are being reexamined and adapted to fit dynamic ecological and institutional contexts in which traditional models of protecting the environment are being replaced by more pragmatic and interventionist approaches less wedded to historical systems and static preservationist ideals ( Camacho et al. 2010 ; Minteer and Collins 2012 ). Furthermore, as we acknowledge the history and extent of human influence and impact on ecological systems—even for the most remote parts of the planet—we are confronted with a changing vision of nature. Instead of a stark contrast between “wild” and “managed,” we now encounter a continuum of systems more or less impacted by human activity, a scale of degrees and increments (rather than absolutes) of anthropogenic influence that upends many customary divisions in conservation science, policy, and ethics (see, e.g., Dudley 2011 ).

A case in point is the weakening division between ex situ, or zoo- and aquarium-based research and conservation, and in situ, or field-based biological research and conservation practice. Global climate change, along with other drivers of rapid environmental transformation (e.g., accelerating habitat loss and the spread of invasive species and infectious diseases), is increasingly being viewed as requiring a more proactive and intensive philosophy of conservation and ecological management ( Hobbs et al. 2011 ). One consequence of this shift is that the conceptual and empirical boundaries separating “the field” from “the animal holding facility” are growing hazy: zoos and aquariums are becoming more engaged in field conservation programs, while preserves and natural areas are becoming more intensively managed and designed for a diverse mix of conservation and resource management outputs ( Cole and Yung 2010 ; Dickie et al. 2007 ; Pritchard et al. 2011 ).

At the same time, there are new calls within conservation science and management circles to think differently about the connections between captive and wild populations. Indeed, many wildlife scientists are recognizing that captive and wild populations should be seen not as separate biological and management domains but viewed instead as linked metapopulations (e.g., Lacy 2012 ). They argue that the sustainability of the former requires exchange of animals and DNA from the wild, whereas the viability of the latter may require contributions from ex situ populations as well as the refinement of small-population research and management techniques ( Lacy 2012 ; Redford et al. 2012 ). Such techniques, however, may only be feasible in the controlled environment of the zoo or aquarium.

The softening of the distinction between ex situ and in situ, the quickening pace of biodiversity loss, and the parallel rise of a more interventionist ecological ethic have significant implications for how we understand and make trade-offs among values and responsibilities in conservation research and practice. These include the concerns of animal welfare and animal rights as well as species-level and ecosystem-level conservation values. Although all of these obligations remain an important part of the ethical landscape of conservation research and practice, they are being reshaped by the need to respond to rapid environmental change as well as by the research demands of a more interventionist conservation effort.

A good example of this trend is the Amphibian Ark Project (AArk), a global consortium of zoos, aquariums, universities, and conservation organizations that has organized itself around the goal of slowing global amphibian declines and extinctions, which by all accounts have reached historic levels over the last several decades ( Collins and Crump 2009 ; Gewin 2008 ; Zippel et al. 2011 ). Zoos and aquariums in the AArk serve as conservation way stations for amphibian populations facing possible extinction because of the combined forces of habitat loss, infectious disease, and climate change. But they also function as centers of research into the drivers of population decline, the possibilities of disease mitigation, and the prospect of selecting for biological resistance to a lethal amphibian pathogen ( Woodhams et al. 2011 ). With the mission of rescuing, housing, and breeding hundreds of amphibian species to return them eventually to native localities, the AArk is emerging as a hybrid or “pan situ” approach to biodiversity protection, a project that integrates (and blurs the borders between) ex situ and in situ conservation ( Dickie et al. 2007 ; Gewin 2008 ).

In addition, the breeding and research activities within the AArk evoke questions of animal welfare and conservation ethics, including the tensions between and within these commitments. Amphibian research can be invasive and even lethal to individual animals, raising significant and familiar welfare and rights-based concerns in zoo and aquarium research. Moreover, infectious disease research, a significant part of the AArk research portfolio, carries the risk of an infected host or the pathogen itself infecting other animals in a captive-breeding facility or even escaping into local populations. In fact, just such a case occurred when the often-lethal pathogen the amphibian chytrid fungus moved from a common species in a captive-breeding facility to an endangered species. When the latter was introduced into Mallorca to establish a population in the wild, subsequent research revealed that animals were infected by the pathogen from the breeding facility before transfer ( Walker et al. 2008 ). Still, it is clear that many amphibian species will experience further declines or go extinct in the wild if dramatic measures such as the AArk are not pursued until a sustainable recovery and conservation strategy is developed.

In what follows, we examine the ethical and policy-level aspects of research and conservation activities that involve captive wildlife in zoos and aquariums, focusing on some of the implications of accelerating biodiversity decline and rapid environmental change. As we will see, the most pressing ethical issues surrounding zoo- and aquarium-based wildlife in this era of rapid global change are not best described as traditional animal rights versus conservation dilemmas but instead concern what we believe are far more complicated and broad-ranging debates within conservation ethics and practice. These debates include devising an ethically justified research and recovery strategy for wildlife across evolving in situ and ex situ conservation contexts that may require a more interventionist approach to biodiversity management. Zoo and aquarium researchers in a time of rapid global change must find creative ways to integrate and steer the expanding biodiversity research efforts of their facilities. In doing so, they will need to provide the ethical justification and scientific guidance for responding to the plight of those globally endangered species that can benefit from controlled and often intensive analysis in ex situ centers.

Ethicists and environmental advocates have often found themselves deeply divided over the moral status of and duties owed to nonhuman animals—a division that has existed despite the common effort among environmental and animal philosophers to expand societal thinking beyond a narrow anthropocentrism (e.g., Callicott 1980 ; Regan 2004 ; Sagoff 1984 ; Singer 1975 ). The dispute is usually attributed to different framings of moral considerability and significance. Animal welfare and animal rights approaches prioritize the interests or rights of individual animals, whereas environmental ethics typically embraces a more holistic view that focuses on the viability of populations and species and especially the maintenance of ecological and evolutionary processes. The difference between these two views can be philosophically quite stark. For example, animal-centered ethicists such as Peter Singer believe that it makes little sense to talk about nonsentient entities such as species, systems, or processes as having their own “interests” or a good of their own (as environmental ethicists often describe them), although they can be of value to sentient beings and thus objects of indirect moral concern.

In the view of ecocentric ethicists such as J. Baird Callicott and Holmes Rolston, however, an ethics of the environment is incomplete if it does not accord direct moral status to species and ecosystems and the evolutionary and ecological processes that produced and maintain them. Most environmental ethicists are sensitive to animal welfare considerations and are certainly aware that many threats to populations, species, and ecosystems impact animal welfare either directly or indirectly. Typically, however, they advocate focusing moral concern and societal action on such ends as the protection of endangered species and the preservation of wilderness rather than reducing the pain and suffering (or promoting the rights or dignity) of wild animals. Domestic animals are even further outside the traditional ambit of environmental ethicists; indeed, their comparative lack of wildness and autonomy has for some suggested a lower moral status as “artifacts” of human technology rather than moral subjects (see, e.g., Katz 1991 ).

It is important to point out here that although “animal rights” is often used as a blanket term for ethical and advocacy positions defending the humane treatment or rights of animals, philosophers and others often make an important distinction between animal rights and animal welfare arguments. The former is generally seen as a nonconsequentialist view of an animal's moral status (i.e., a view on which the covered class of individuals is entitled to fair treatment following ascriptions of moral personhood or inherent worth similar to the logic of entitlement we ideally accord individual human persons). Alternatively, the welfare position is traditionally rooted in consequentialist moral reasoning whereby the impacts of decisions and actions affecting the interests or good of the animal are weighed against other goods (including the interests and preferences of humans), and decisions are made based on an assessment of the aggregate good of a particular action, all things being equal. What this means is that, although in many cases both animal rights and animal welfare philosophies will justify similar policy and practical outcomes, in some instances the welfare position may be more accommodating to animal harms when these are offset by the net benefits produced by a particular action or rule. It bears emphasizing, however, that calculations of these benefits and harms must be fair and consistent; they cannot give arbitrary weight to human preferences simply because they are anthropocentric in nature, and all interests—including those of the animal—must be considered.

Not surprisingly, these different approaches to moral consideration have often produced sharp disagreements at the level of practice, especially in wildlife management and biological field research. For example, animal rights proponents regularly condemn wildlife research and management practices that inflict harm or even mortality upon individual animals, such as the lethal control of invasive species, the culling of overabundant native wildlife, and the use of invasive field research techniques; practices that have for decades been widely accepted among wildlife and natural resource managers (e.g., Gustin 2003 ; Smith 2007 ). Controversial cases such as the reduction of irruptive whitetail deer populations threatening forest health in New England ( Dizard 1999 ), amphibian toe clipping in capture–mark–recapture field studies ( May 2004 ), the hot branding of sea lions for identification in marine research projects ( Minteer and Collins 2008 ), and the culling of black-throated blue warblers for an ecological field experiment ( Vucetich and Nelson 2007 ) illustrate the ethical conflicts characterizing much of the environmental/conservation ethics and animal welfare/rights debate in wildlife field research.

Despite attempts by some ethicists and scientists to find common ground between animal- and environmental-centered values at either the philosophic or pragmatic level (e.g., Jamieson 1998 ; Minteer and Collins 2008 ; Minteer 2012 ; Perry and Perry 2008 ; Varner 1998 ), many observers believe that the gulf separating ethically individualistic, animal-centered commitments and conservationists’ more holistic commitment to promoting the viability of populations and communities is simply too wide to bridge, even in cases where animal-centered and biodiversity-centered advocates have common cause ( Hutchins 2008 ; Meffe 2008 ).

This division has recently been reinforced by public stances taken by wildlife conservation organizations such as The Wildlife Society (TWS), which in 2011 released a position statement on animal rights and conservation that underscored what the organization described as the incompatibility between these two ethical and policy orientations ( http://wildlife.org/policy/position-statements ). Animal-centered views perceived as more moderate in nature, such as the commitment to the humane treatment of animals in research and management (i.e., a weaker animal welfare position) are ostensibly accepted by TWS, although the organization's position here probably still falls short of what animal welfare ethicists such as Singer would argue is demanded by a principled concern for animal well-being in research and management contexts.

The practice of keeping animals in zoos and aquariums is one of the more intriguing areas of conflict within the animal ethics–conservation ethics debate. The presumption that the keeping of animals in captivity in zoos and aquariums is morally acceptable has long been questioned by animal rights–oriented philosophers who believe that such facilities by definition diminish animals’ liberty and dignity as beings possessing inherent worth (e.g., Jamieson 1985 , 1995 ; Regan 1995 ). Such critiques either implicitly or explicitly evoke the unpleasant history (from both the contemporary welfare and wildlife conservation perspective) of zoos as wildlife menageries designed primarily for public titillation and entertainment, including notorious cases of animal abuse and the exploitation of captive wildlife for profit. Zoo advocates, however, argue that modern zoos and aquariums have a vital societal mission to educate zoo visitors regarding the necessity of wildlife conservation and the dilemma of global biodiversity decline and that they contribute (and could contribute even more) significantly to fundraising efforts to support conservation projects in the field (e.g., Christie 2007 ; Hutchins et al. 1995 ; Zimmerman 2010 ).

This broad ethical debate over zoos and aquariums in society and the various trade-offs it evokes regarding animal welfare, conservation, scientific research, and entertainment have been complicated by particular high profile cases, such as the keeping of elephants or large carnivores in zoos ( Clubb and Mason 2003 ; Wemmer and Christen 2008 ) and whales or dolphins (cetaceans) in aquariums and marine parks ( Bekoff 2002 ; Grimm 2011 ; Kirby 2012 ). Among other issues, these cases often reveal disagreements among scientists about conditions for housing some of the more charismatic, large, and popular animals in zoos away from in-range conditions as well as differences in assessments of species-specific welfare impacts and requirements across a range of taxa ( Hosey et al. 2011 ). They also exemplify the welfare–entertainment–education–conservation nexus that forms much of the normative and ethical discourse around zoos in modern society ( Hancocks 2001 ; Hanson 2002 ).

Zoos and aquariums therefore raise a number of ethical issues, from the basic question of the moral acceptability of keeping animals in captivity to more specific arguments and debates over practices such as captive (conservation) breeding, zoo-based research, wild animal acquisition, habitat enrichment, and the commercialization of wildlife (see, e.g., Davis 1997 ; Kreger and Hutchins 2010 ; Norton et al. 1995 ). Clearly, these practices provoke a set of complicated questions about our responsibilities to captive animals and the conservation of species and habitats in the wild.

Perhaps one of the strongest conservation-based arguments supporting housing animals in zoos and aquariums today is that these facilities provide the ability to create “captive assurance populations” through ex situ breeding, with the goal of reintroducing some individuals back into the wild to restore or expand lost or declining populations ( Beck et al. 1994 ; Reid and Zippel 2008 ). This technique, described earlier in our discussion of the AArk, has produced some notable conservation successes in recent decades, including the recovery of (among other species) the Arabian oryx, the black-footed ferret, and the California condor. On the other hand, many animal rights–oriented critics of conservation breeding and the reintroduction efforts of zoos, such as the advocacy organization People for the Ethical Treatment of Animals (PETA), argue that captive breeding efforts are biased toward the breeding of “cute” animals of value to the public (rather than breeding for conservation purposes) and that such practices create surplus animals that are subsequently transferred to inferior facilities and exploited ( www.peta.org/about/why-peta/zoos.aspx ). PETA questions as well the broader goal of releasing captive-born and raised animals to the wild, pointing out the inherent difficulties surrounding reintroductions, including the risks they pose to the reintroduced animals and other wildlife in situ. Although these sorts of challenges have also been noted by wildlife biologists and biodiversity scientists, many advocates of conservation breeding and reintroduction programs have argued that further research and improved biological assessment and monitoring efforts can improve the likelihood of success for the release or reintroduction of captive animals to the wild ( Earnhardt 2010 ; Fa et al. 2011 ).

The data suggest that zoos and aquariums are playing an increasingly significant role in field conservation programs and partnerships. In its 2010 Annual Report on Conservation Science, the Association of Zoos and Aquariums (AZA) lists zoos engaged in more than 1,970 conservation projects (i.e., activities undertaken to benefit in situ wildlife populations) in over 100 countries ( www.aza.org/annual-report-on-conservation-and-science/ ). The AZA coordinates taxon advisory groups and species survival plans to manage conservation breeding, develop in situ and ex situ conservation strategies, and establish management, research, and conservation priorities ( www.aza.org/ ). These experts (which include biologists, veterinarians, reproductive physiologists, and animal behaviorists, among other researchers) also contribute to the development of taxon-specific animal care manuals that provide guidance for animal care based on current science and best practices in animal management ( www.aza.org/animal-care-manuals ).

As part of their expanding efforts in field conservation, ex situ wildlife facilities are also becoming more significant players in biodiversity research. As Wharton (2007) notes, systematic, zoo-based research on reproduction, behavior, genetics, and other biological dimensions has made many important contributions to the improvement of animal husbandry practice over the past three decades. Moreover, ex situ animal research conducted to inform field conservation is seen as a growing priority for zoos and aquariums, especially in light of worrying trends in global biodiversity decline and the widely acknowledged potential of the extensive zoo and aquarium network to carry out studies that can provide conservation-relevant knowledge for field projects ( WAZA 2005 ; MacDonald and Hofer 2011 ).

Applied research in zoological institutions (i.e., research motivated by the goal of improving conservation and/or veterinary science) is not the only research contribution of zoos and aquariums, however. Basic research on captive wildlife is also conducted throughout the system and is highly valued by many wildlife scientists, both within and outside of zoological institutions. At Zoo Atlanta, for example, researchers are presently conducting a number of studies designed to inform our understanding of wildlife biology, including the biomechanics of sidewinding locomotion in snakes, social behavior and acoustic communication in giant pandas, and taxonomic and phylogenetic studies of frogs, among other taxa (J. Mendelson, Zoo Atlanta, personal communication, 2012). Such research is often impossible to conduct in the wild, and thus captive populations can hold great value as specimens for basic scientific study.

Although not every zoo and aquarium has the capacity to conduct extensive animal research (focused on either veterinary/animal care or conservation purposes), the larger and better-equipped facilities such as the Bronx Zoo, the San Diego Zoo, Zoo Atlanta, the Monterey Bay Aquarium, and the St. Louis Zoo have become active wildlife and conservation research centers in addition to being popular educational and entertainment facilities. For all these reasons, zoos, aquariums, and other ex situ facilities (e.g., botanic gardens) are being championed by organizations such as the World Association of Zoos and Aquariums as potential models of “integrated conservation” given their ability to participate in a wide range of conservation activities, from ex situ research, education, and breeding of threatened species to field projects in support of animals in the wild to serving (in the case of the AArk) as temporary conservation rescue centers to protect animals threatened by rapid environmental change ( WAZA 2005 ; Zippel et al. 2011 ). Whether these facilities can develop successful reintroduction programs that will lead to the ultimate recovery of populations they are holding temporarily (such as the AArk program) or whether these “temporary” efforts become de facto and permanent ex situ “solutions” to particular wildlife conservation problems in the field, however, remains to be seen.

For many wildlife biologists and conservationists, then, breeding and conservation-oriented research on captive wildlife are seen as essential activities that should not be halted on the basis of animal welfare and animal rights objections. The ethical imperative to save threatened species from further decline and extinction in the wild has for them a priority over concerns regarding individual animal welfare. Humane treatment of animals (both ex situ and in the field), however, remains a clear ethical obligation of zoo-based scientists and professionals as well as field researchers. It is an obligation formalized in the ethical codes of the major professional and scientific societies, such as the AZA and the Society for Conservation Biology.

Yet not everyone is convinced that this reinvigorated conservation justification for keeping animals in captivity is a compelling rationale for such facilities. For example, some critics have argued in the past that actual conservation-relevant research conducted in or by zoos and aquariums is, in fact, a relatively minor part of their mission and that it cannot justify keeping animals in captivity (see, e.g., Jamieson 1995 ). Such criticisms are, however, slowly losing their bite as we witness the more recent growth of zoo-based research for conservation purposes ( Stanley Price and Fa 2007 ). Still, it is true that much of the research conducted by zoos today remains focused on animal husbandry rather than conservation of animals in the wild ( Fa et al. 2011 ).

This situation may be changing, however. Indeed, research on captive wildlife in zoos and aquariums (including that driven by conservation concerns) is predicted to continue to grow in significance in the coming decades. Perhaps the most obvious reason for this is access. As mentioned above, scientists in ex situ facilities have the ability to carry out potentially high-impact research projects on captive animals that may be too costly, risky, or logistically impossible to perform on small, wild populations in situ ( Barbosa 2009 ). This research can be valuable for improving animal husbandry in zoos and aquariums, but it can also be useful for augmenting field conservation projects because biological data from captive animals is incorporated in the planning and implementation of field interventions ( Wharton 2007 ). Data collected from animals drawn from populations that only exist in small numbers in the wild are particularly valuable; therefore, captive populations afford important opportunities to collect data on rare species in a controlled and safe environment.

To the degree that research on zoo and aquarium wildlife is used to inform and improve efforts to conserve and manage vulnerable wildlife populations in the field, it may be defended as an ethically justified activity according to the more holistic obligation to promote species viability and ecosystem health—even if it includes techniques that disrupt or harm captive wildlife in the process. Yet, these activities could still be challenged by more animal rights–based arguments that claim that such harms, including the fundamental loss of freedom and the degradation of an animal subject's dignity associated with captivity, can never be offset by the production of beneficial biological consequences at the population or species level (i.e., “good consequences” in the aggregate cannot justify the violation of the moral duty to respect the worth of the individual animal).

For an animal welfare proponent willing to take a more pragmatic position, however, unavoidable harms or disvalues in zoo and aquarium research projects that directly lead to the promotion of the good of the species in the wild may be viewed as ethically tolerable in light of the collective benefit for sentient animals. This view could follow from the utilitarian principle to evaluate an action based on its consequences for all sentient beings impacted by the action or from a more integrated ethical system in which both animal welfare and conservation ethics are operant in moral decision making (see, e.g., Minteer and Collins 2005a , 2005b ). Indeed, we suspect that most informed animal welfare supporters also see the value of wildlife conservation and landscape protection (or at least are not opposed to these activities). Therefore, they should not dismiss the real population, species, and ecosystem benefits of research on captive wildlife, especially in a time of global change.

The ethical evaluation of research on captive wildlife, however, can become even more complicated, especially if one holds the foundational view that it is wrong to place animals in captivity in the first place. Research undertaken primarily to improve animal care in ex situ facilities, for example, would appear to be a morally justifiable activity, especially if it produces results than can help zoo managers enrich habitats and improve the health and well-being of wildlife in their care. That is, the research would seem to produce a positive value that deserves to be weighed against any disvalue produced by harming or stressing an animal during the research process. And yet, this research could still be seen as morally unacceptable even if it improves the welfare of captive animals because it destroys the animal's freedom or treats them as a “mere means” to some anthropocentric end. Therefore, according to this abolitionist position, zoo and aquarium wildlife research conducted under the banner of improving animal care or husbandry makes the mistake of assuming that keeping animals in zoos and aquariums is itself defensible, a stance that many arguing from a strong animal rights framework flatly reject (e.g., Jamieson 1985 , 1995 ; Regan 1995 ).

But what about the case where research on captive wildlife is demonstrated to be necessary to obtain information relevant to the conservation and management of threatened populations in the wild? In such situations, strong ethical objections to the keeping of animals in ex situ facilities, to interfering in their lives, and so forth arguably have comparatively less normative force. To reject this claim, one would have to argue that the well-being of captive animals is and should be a completely separate moral issue from the welfare of wild populations—a position that, as mentioned earlier, is difficult to hold in our increasingly integrated conservation environment. This does not entail the rejection of animal welfare considerations in research design and conduct; these remain compelling at all stages of the research process. But it provides a powerful and morally relevant consideration for undertaking that research rather than ruling it out on moral grounds.

We should underscore that this conclusion does not hold for poorly designed or weakly motivated research projects that promise to shed little new scientific light on wildlife biology and behavior relevant to conservation or that appear to essentially reproduce studies already performed on either captive or wild animals in the field ( Minteer and Collins 2008 ). Determining the conservation value of the proposed research and its scientific necessity is thus a critical activity bearing on the welfare and conservation of animals across in situ and field settings. Yet it is an analysis that necessarily contains a measure of uncertainty that can complicate evaluations and proposed trade-offs among animal welfare, scientific discovery, and the potential for the research to produce results with a direct application to the conservation, management, or recovery of populations in the wild ( Parris et al. 2010 ).

Improved husbandry and conservation value in the field are not the only potential benefits of zoo and aquarium research for wildlife, however. As Lewis (2007) notes, research on captive animals in ex situ facilities may also yield results that can pay dividends in the form of improved animal welfare in field research projects. This is especially true in the case of zoos and aquariums with extensive veterinary departments with the capacity to develop equipment and protocols that minimize research impacts on wildlife in field studies. Such projects might include research on novel, less-invasive animal marking and sampling techniques, the development of safer forms of darting and the use of anesthesia, and the creation of new breeding techniques for recovering particular wild animal populations ( Lewis 2007 ). Although it is not always entirely clear which interventions should be considered invasive in the animal research context or what exactly constitutes harm in these analyses (see, e.g., Goodrowe 2003 ; Parris et al. 2010 ; Pauli et al. 2010 ), it does seem to be the case that wildlife researchers in both ex situ and field study environments are increasingly adopting noninvasive sampling and study techniques for wildlife research, signifying, perhaps, a growing sensitivity to animal welfare in field biology and conservation ( Robbins 2009 ).

If ex situ research on animals can lead to the development of less-invasive technologies and research protocols, then some of the welfare concerns raised by the manipulation or harm of zoo and aquarium animals in the research process that produces these technologies may be offset, at least to a degree and at the aggregate (i.e., population, species, and ecosystem) level, by the net welfare benefits of adopting these less-invasive tools and techniques in biological field research. It is important to note once again, however, that this judgment will likely still not satisfy strict animal rightists who typically resist such attempts at “value balancing” (see e.g., Regan 2004 ). Furthermore, and as mentioned above, acceptance of animal harms in such research should hold only as long as the research in question is judged to be scientifically sound and well-designed (i.e., as long as it does not run afoul of the “reduction, refinement, and replacement” directives of the use of animals in the life sciences, which are designed to minimize the impact of research activities on animal welfare and screen out research designs that are not ethically justified, scientifically necessary, or efficient ( Russell and Burch 1959 ).

It is clear that ex situ facilities such as zoos and aquariums will continue to increase in importance as centers of scientific research and conservation action in the 21st century ( Conde et al. 2011 ; Conway 2011 ; Fa et al. 2011 ). The forces of global environmental change, including climate change, accelerating habitat loss, and the spread of infectious diseases and invasive species, along with the synergies among these and other threats, are currently exerting great pressure on wild species and ecosystems. This pressure is expected to only increase in the coming decades ( Rands et al. 2010 ; Stokstad 2010 ; Thomas et al. 2004 ). These dynamics have suggested to many zoo scientists and conservationists an expanding role for many zoos and aquariums in wildlife protection. They can function as safe havens for the more vulnerable species threatened in the wild, as research institutions seeking to understand the impact of global environmental change on wildlife, and as active players in the increasingly intensive process of wildlife conservation in situ, including population management and veterinary care ( Conway 2011 ). As Swaisgood (2007) points out, with the requirement of more intensive managerial interventions in the field because of human encroachment, habitat modification, and other changes, many of the issues central to zoo research and conservation (including animal welfare, the impacts of human disturbance on wildlife, and the consequences of the introduction of animals into novel environments) are increasingly drawing the interest of wildlife researchers and managers in natural areas and in situ conservation projects.

All of these conditions speak to the necessity of wildlife research in zoos and aquariums for informing conservation science under conditions of rapid environmental change, including (most notably) research on the effects of climate change on animal health ( MacDonald and Hofer 2011 ). For example, aquariums can simulate climate change impacts such as shifts in temperature and salinity, the effects of which can be studied on fish growth, breeding, and behavior ( Barbosa 2009 ). Such research could contribute to our understanding of the stresses exerted by global change on wildlife and consequently inform and improve conservation and management efforts in situ.

Another line of research in the domain of global change biology (and wildlife adaptation to environment change) includes studies of captive animals’ responses to pathogens and emergent diseases, such as the work undertaken as part of the aforementioned AArk ( Woodhams et al. 2011 ). Notably, these investigations could allow scientists to gain a better grasp of the consequences of temperature variations and disease transmission for the health of wild populations before any effects take hold ( Barbosa 2009 ). The AArk example illustrates the kind of ethical balancing that needs to be performed for claims surrounding animal and species-level welfare and the health and historic integrity of ecosystems. For many amphibian species, AArk is a place of last resort. Once the amphibian chytrid enters an ecosystem, at least some susceptible species will not be able to return to their native habitats without an intervention strategy such as selective breeding for infectious-disease tolerance. An alternative tactic is managed relocation (i.e., the translocation of populations from their native habitat to novel environments that may be well outside their historic range) (e.g., Schwartz et al. 2012 ). Both approaches, however, involve ethical decisions that balance the welfare of individual frogs and salamanders against that of populations and species as well as the historic integrity of ecosystems (i.e., the particular mix of species and communities that have evolved in these systems over time) ( Winston et al. in press ).

Health- and disease-oriented wildlife research in zoos and aquariums may not only be targeted at wildlife conservation. The public health community, for example, may also have a significant role to play in zoo research in the near term. Epidemiologists and others have noted the value of zoo collections for biosurveillance (i.e., as biological monitoring stations that can be studied to understand and plan for the emergence of future infectious diseases posing public health risks) ( McNamara 2007 ). This proposal raises two further interesting ethical questions regarding the evaluation of zoo- and aquarium-based research under global change: ( 1 ) the acceptability of wildlife health research motivated by improving field conservation of the species and ( 2 ) wildlife health research that enlists captive wildlife as “sentinels” ( McNamara 2007 ) to provide an early warning system for infectious diseases that might impact human welfare. Both research projects could be pursued under the banner of “wildlife, health, and climate change,” yet each would differ in its underlying ethical justification. One program would likely be more species-centered or nonanthropocentric (wildlife health research for conservation purposes), whereas the other would presumably be defended on more anthropocentric grounds, given the focus on safeguarding public health. This philosophic division, however, is not always that well defined, especially if wildlife health research in zoos and aquariums has benefits for both in situ conservation and more human-centered interests (e.g., the provision of ecosystem services). Still, the different research foci would be expected to evoke some differences in ethical analysis regarding their implications for animal welfare, conservation, and human welfare ethics.

For a swelling number of cases, then, scientific study and refinement of conservation breeding techniques, wildlife health research, and so forth will likely be necessary to save focal species in the wild under dynamic and perhaps unprecedented environmental conditions ( Gascon et al. 2007 ). Ethical objections to conservation breeding or to the impacts of high-priority conservation research on captive wildlife motivated by animal welfare and rights concerns will, we believe, become less compelling as the need for captive assurance populations increases (because of the impacts of global change). These ethical objections will also weaken as we see the rise of additional partnerships between ex situ and field conservation organizations and facilities and especially as the former become more directly engaged in recovery and reintroduction efforts that benefit animals in the wild. It is one thing to evaluate captive-breeding programs designed to provide a steady supply of charismatic animals for zoo display. These have rightly drawn the ire of animal advocacy organizations as discussed earlier. It is another thing to assess those activities with the goal of recovering wildlife populations threatened in the field because of accelerating environmental change.

This does not mean that the ethical challenges of recognizing and promoting animal welfare concerns in ex situ research and conservation will or should be swept aside but rather that the more significant (and often more demanding) ethical questions, at least in our view, will take place on the species conservation side of the ethical ledger. These challenges will include the task of accommodating a philosophy of scientific and managerial interventionism in wildlife populations and ecological systems as rapidly emerging threats to species viability and ecosystem health move wildlife researchers and biodiversity managers into a more aggressive and preemptive role in conservation science and practice ( Hobbs et al. 2011 ; Minteer and Collins 2012 ). The risks attached to this shift include creating further ecological disruption by intervening in biological populations and systems, and a more philosophic consequence—the transgression of venerable preservationist ideals that have long inspired and motivated the efforts of conservationists and ecologists to study and protect species and ecosystems.

For example, ethical dilemmas surrounding the translocation of wildlife populations from native habitats to new environments, including temporary relocations to ex situ facilities such as zoos and aquariums, raise a set of difficult technical, philosophic, and ethical questions for conservation scientists and wildlife biologists ( Minteer and Collins 2010 ). Beyond the animal welfare or animal rights concerns about handling and moving animals that may experience considerable stress (or even mortality) during this process, such practices will also have implications for (1) the original source ecosystems (i.e., the community-level impacts of removing individuals from populations stressed by climate change), (2) the temporary ex situ facility that houses the animals (including shifts in resources and collection space as well as risks of disease transmission) (e.g., Greenwood et al. 2012 ), and (3) the native species present in the eventual “recipient” ecosystems once the wildlife are introduced ( Ricciardi and Simberloff 2009 ).

Another example is the practice of ecological engineering for species conservation in the wild, which can involve the significant modification (and even invention) of habitat to improve field conservation efforts. Along these lines, Shoo et al. (2011) have proposed considering and testing a number of interventionist approaches to the conservation of amphibian populations threatened by climate change. These include activities such as the manipulation of water levels and canopy cover at breeding sites as well as the creation of new wetland habitat able to support populations under variable rainfall scenarios. The investigators suggest employing an adaptive management protocol to experimentally determine whether and to what extent such manipulations are effective in the field.

Such conservation challenges and others like them ultimately compel us to rethink our responsibilities to safeguard declining species and promote ecosystem integrity and health in an increasingly dynamic environment. We believe that this analysis will also require a reassessment of wildlife research priorities and protocols (including the relative significance of animal welfare concerns in research and conservation) for some time to come.

The ethical terrain of zoo and aquarium research and conservation is experiencing its own rapid and unpredictable shifts that mirror the accelerating pace of environmental and societal change outside these facilities. What is required, we believe, is a more concentrated engagement with a range of ethical and pragmatic considerations in the appraisal of animal research under these conditions. The growing vulnerability of many species to the often lethal combination of climate change, habitat degradation, emerging infectious diseases, and related threats has created a sense of urgency within the biodiversity science community. We need to respond with research agendas that can help to understand and predict the impact of these forces on the viability of populations and species in the wild and to inform actions and policies designed to conserve these populations and species.

Part of this ethical appraisal will require asking some hard questions of zoos and aquariums regarding their priorities and abilities to assume this more demanding position in conservation science, especially because some observers have suggested a need for greater planning and research capacity in these facilities ( Anderson et al. 2010 ; Hutchins and Thompson 2008 ). Zoological institutions are idiosyncratic entities, and thus there is often a great deal of variability in how particular zoos and aquariums interpret their conservation mission (J. Mendelson, Zoo Atlanta, personal communication, 2012). The divide between mission and practice can produce significant challenges for these institutions as they take on a more aggressive conservation role. For example, and as mentioned above, many would argue that it is critical for zoos and aquariums to avoid becoming the final stop for species threatened in the wild. Instead, they should be true partners in what we have called an integrated, pan situ conservation management strategy across captive, wild, and semiwild contexts. The development by zoos and aquariums of more explicit reintroduction plans in such cases would therefore help ensure that their conservation ethic remains compatible with that of the wider community, which generally favors the maintenance of wild populations (i.e., in situ conservation) whenever possible.

One implication of this move by zoos and aquariums toward a more expanded research and conservation mission is that it will likely affect other zoo programs that have long dominated the culture and activities of zoo keeping. The display of exotic animals for public entertainment, for example, may be impacted as zoos and aquariums attempt to carve out more space for research and conservation activities, both in their facilities and in their budgets. On this point, Conway (2011) proposes that zoos will need to commit to creating more “conservation relevant zoo space” as they make wildlife preservation (and not simply entertainment and exhibition) their primary public goal. Yet such a shift in mission and programs could undercut public support for zoos, especially to the extent that the traditional displays of charismatic wildlife are reduced to accommodate a stronger conservation and research agenda.

An increased emphasis on climate change and its biodiversity impacts, too, could pose a challenge to zoos and aquariums wary of promulgating a negative or doom-and-gloom message to their visitors. Although some facilities are embracing this challenge and making climate change a part of their conservation education programming, some zoos and aquariums are struggling to incorporate this message within their more traditional educational and entertainment aims. For example, the Georgia Aquarium has apparently assured visitors that they will not be subjected to material about “global warming,” a concession, according to the aquarium's vice president for education and training to the conservative political leanings of many of the facility's guests ( Kaufman 2012 ). This example speaks to the larger challenge of moving zoos and aquariums into a stronger position of global leadership in conservation education, research, and practice under global change and other major threats to habitat and population viability in the coming decades.

Animal rights and welfare concerns will continue to be relevant to the evaluation of research and conservation activities under global change, but ultimately a more sophisticated and candid analysis of the trade-offs and the multiple imperatives of conservation-driven research on captive populations is required. Our understanding of these responsibilities—and especially the requirement of balancing animal well-being in practice in wildlife management and conservation policy—must evolve along with rapid climate change, extensive habitat fragmentation and destruction, and related forces threatening the distribution and abundance of wildlife around the globe. Unavoidable animal welfare impacts produced as a result of high-priority and well-designed conservation research and conservation activities involving captive animals will in many cases have to be tolerated to understand the consequences of rapid environmental change for vulnerable wildlife populations in the field. It will allow recovery and promote the good of vulnerable species in the wild more effectively under increasingly demanding biological conditions. Inevitably, these changes will continue to blur the boundaries of in situ and ex situ conservation programs as a range of management activities are adopted across more or less managed ecological systems increasingly influenced by human activities.

We thank Dr. Joseph Mendelson (Zoo Atlanta) and Dr. Karen Lips (University of Maryland) for their helpful comments and suggestions on an earlier version of this paper.

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Home — Essay Samples — Environment — Animal Welfare — Why Wild Animals Should Be Conserved In Captivity

Why Wild Animals Should Be Conserved in Captivity

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Marine mammals in captivity

Dolphins, whales and other marine mammals don’t belong in tanks on public display

The public display industry keeps many species of marine mammals captive in concrete tanks, especially whales and dolphins. The Humane Society of the United States believes that these animals are best seen in their natural coastal and ocean environments instead of being held captive simply to entertain people.

Life in the wild

The very nature of these animals makes them uniquely unsuited to confinement. In the wild, whales and dolphins live in groups, often in tight family units. Family bonds often last many years. In some species, they last for a lifetime.

Whales and dolphins travel long distances each day, sometimes swimming in a straight line for a hundred miles as they search for food and socialize, other times remaining in a certain area for hours or days, moving for miles along a coastline and then turning to retrace their path. These marine mammals can dive up to several hundred meters and stay underwater for half an hour or more. They would normally spend only 10 to 20 % of their time at the surface.

The sea is to whales and dolphins much as the air is to birds—a three-dimensional environment, where they can move up and down and side to side. But whales and dolphins don't stop to perch. They never come to shore, as seals and sea lions do. Whales and dolphins are always swimming, even when they "sleep." They are "voluntary breathers," conscious during every breath they take. They are always aware and always moving. Understanding this, it is difficult to imagine the tragedy of life in no more than a tiny swimming pool.

Life in captivity

Life for captive whales and dolphins is nothing like a life in the sea. It is almost impossible to maintain a family group in captivity as animals are traded among different facilities. Their tanks allow only a few strokes in any direction before coming to a wall. Because tanks are shallow, the natural tendencies of whales and dolphins are reversed—they must spend more than half their time at the tank's surface.

This unnatural situation can cause skin problems. In addition, in captive killer whales (orcas), it is the probable cause of dorsal fin collapse. Without the support of water, gravity pulls their tall, top fins over as the whale matures. Collapsed fins are experienced by all captive male orcas and many captive female orcas. However, they are observed in only about one % of orcas in the wild.

In a tank, the environment is monotonous and limited in scope. Sonar clicks, the method by which individuals navigate and explore their surroundings, have limited utility in such an environment. These animals, who are perpetually aware, have nothing like the varied stimulation of plants and fish and other animals in their natural environment. In perpetual motion, they are forced into literally endless circles. Life for these animals is a mere shadow of what it was in the wild.

The problem

What must life be like for these complex, gregarious, three-dimensional creatures who must live in a comparatively bland concrete enclosure? The parents or grandparents of most of the dolphins in captivity in the United States were captured from the wild. Some nations still capture and sell them.

At first look, a whale or dolphin show may seem exciting, even for the animals. But when you look past the show to the high mortality rates and stress-related causes of death in captive whales and dolphins, the effects of captivity suggest a far harsher reality. The public display of whales and dolphins in marine parks and aquariums is waning in Europe and Canada, but it is still common in the United States and is increasing in developing countries, particularly those in Asia.

Although seals and sea lions may breed readily in captivity, only a few species are held in numbers large enough to sustain a breeding population. Some species of whales and dolphins, on the other hand, do not breed well in captivity and some have never produced surviving offspring. Many of the captive dolphins and whales have shorter life expectancy than others of their species who still live in the wild.

The businesses that charge the public to see and interact with whales and dolphins in captivity contend that public display serves educational and conservation purposes. However, experience has proven that public display does not effectively educate the public who generally learn little of value about the animals that are on display in shows and swim-with facilities. Profit, not education, is the reason they are captive in zoos and aquariums. For a marine mammal, tanks are prisons. The monotonous, confined life of animals in captivity is a mere shadow of what life was like for them in the wild. The Humane Society of the United States believes that animals in bare tanks do not present a realistic image of natural behaviors or natural habitats. Marine mammals are best protected by cleaning up and protecting their habitats. Truly appreciating them means seeing them along the coast and in the rich ocean environment where they belong.

Animal Captivity: Justifications for Animal Captivity in the Context of Domestication

First Online: 22 September 2016

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Bernice Bovenkerk 5

Part of the book series: The International Library of Environmental, Agricultural and Food Ethics ((LEAF,volume 23))

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The central question of this chapter is whether keeping animals in captivity is morally justified. Captivity could be considered inherently wrong when animals are perceived to have an interest in liberty. I argue that this is the case to a certain extent, provided that we use a less stringent notion of autonomy than we do for humans. Next, I address two possible general moral justifications for keeping animals in captivity: (1) it is in the interest of humans to keep animals in captivity and (2) it is in the interest of the animals themselves. Whether these justifications are successful is to a large extent an empirical matter. In general, however, we could say that either animals of a specific species do not have sufficient adaptive capacity to be able to deal with conditions of captivity—in which case harm to the animals’ welfare occurs—or they do have this capacity, but this means that their genetic make-up changes over the generations, and they ultimately become domesticated. This aspect of domestication raises a whole new set of questions regarding the justifiability of animal domestication. I argue that the questions raised by animal domestication cannot be completely dealt with within traditional animal ethical approaches, that take individual animals as the sole unit of moral concern. Objections that people voice regarding animal captivity and in particular regarding the often resulting domestication and interfering with an animal’s genetic make-up, are more properly directed at the species-level.

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This at least was the outcome of interviews I held with stakeholders in the Netherlands about pedigree dog breeding in 2015 and 2016.

Cochrane ( 2009 , 662) follows Feinberg ( 1984 ) in taking interest to mean “to have some kind of stake” in something. One has a stake in something when one’s well-being is affected by it. Well-being is taken to be a prudential value, in other words, “well-being relates to how well things are going for the individual whose life it is ” (italics in original).

This marginal cases argument has been criticized, for example by Carruthers ( 1992 ) for leading to a slippery slope where in the end we cannot attribute moral status to any human beings either and by Cohen ( 1986 ) and Scruton ( 2000 ) who argue that regardless of their mental capacities humans are the ‘kinds’ of beings who deserve moral status. These arguments have successfully been countered by Tanner ( 2006 , 2009 ).

There are notable exceptions, such as Frey ( 1988 ).

Thanks to Jeroen Hopster for pointing this out to me.

This is supported by current thinking by biologists who posit the idea of ‘inclusive inheritance’. Still, one can wonder, of course, whether the distinction between qualitative and quantitative differences is itself not one of degrees. Thanks to Jeroen Hopster for bringing this point to my attention.

Of course, another argument against this view is simply that we are making an is/ought fallacy if we are basing normative conclusions about the moral status of humans on the fact that we feel more sympathy towards other humans. See also Palmer ( 2010 , 51–54) for a critical discussion of the care ethical move to base obligations on affection.

A study has shown, for example, that gorillas in zoos that are confronted with many visitors are more likely to show stereotypic behaviour—consisting of autogrooming, abnormal behaviour (such as teeth clenching, body rocking, and more banging on the separation barrier) taking less rest, and aggression towards other gorillas—than those who are confronted with low visitor density. This indicates that visitor density leads to stress in the animals. See Wells ( 2005 ), who also cites other studies with similar conclusions.

Despite claims to the contrary. For example, as the documentary Blackfish shows, Sea World advertises that orcas live up to the age of 40 in captivity, while they live much shorter lives in the wild. In fact, male orcas live up to 50 years in the wild and female ones can even live up to 90 years.

Disagreement is possible about the question whether this premature killing of captive animals can count as a harm and the question rises how to offset lifespan against other benefits that the animals may enjoy by being held in captivity. Some (for example Haynes 2008 ) argue that killing should be regarded a welfare problem while others argue that shortening an animal’s life in itself is not problematic (for example Singer 2011 ).

The theory of learned helplessness was first put forward by psychologist Seligman ( 1972 ), who showed that dogs that have been given electric shocks become so passive that they fail to avoid further adverse stimuli, even if there is an easy possibility of escape. They are in effect conditioned to believe that harm is inescapable.

I am assuming here that the animals’ welfare is not violated in either of the three views on welfare. If it’s genetic make-up is altered to the extent that it can cope well with loss of freedom, that it experiences no negative feelings from this lack of freedom, and its natural behavioral repertoire is changed so that it can carry out its ‘new’ natural behavior in captivity, there is no clear welfare problem.

Needless to say, there is disagreement about this. For example, Singer ( 1975 ) argues that freedom is more important to animals than the protections offered by domestication, but Budiansky ( 1992 ) takes the opposite position.

Think for example of experiments with rats that could self-administer drugs and stopped eating entirely.

This depiction of the domestication of dogs is disputed by Coppinger and Coppinger ( 2001 ) who argue that ‘the canid family tree split, and wolves and dogs went along their separate branches. The wolf displays specialized adaptation to wilderness, and the dog displays specialized adaptations to domestic life’.

It should be noted that while this is a difference between (most) humans and animals, according to most animal ethical theories this is a morally irrelevant difference; it is no adequate basis for treating animal and human interests differently (see Sect 3 ). After all, marginal cases cannot give informed consent as free equals either. Only for contractarian theories this would be a morally relevant difference between humans and animals, but they cannot give an adequate answer to the marginal cases argument.

Cited by Palmer ( 1997 ).

One could wonder why ‘the wild’ should be the reference point for how animals should be treated. The assumption that social contract theories make is that tacitly agreeing to a hypothetical contract marks the transition from a state of nature to a state of culture and the ‘wild’ here refers to the situation before animals were domesticated.

It should be noted that the inability to survive in the wild is often the result of the lack of an apt environment or of a careful rewilding process, and is not always irreversible. Thanks to Franck Meijboom for pointing this out to me. Yet, in the case of pedigree dogs, they would most likely not be able to survive in the wild or be able to go back to a wild dog-like state.

Macnaghten ( 2001 ) reports on research into public attitudes towards animals and biotechnology and finds that for example the argument that genetic modification is unnatural is raised. This unnaturality seems to refer more to changing a whole species than only an individual animal.

We could make judgments about whether the animal’s life is worth living in absolute terms, but as long as the animal’s life is deemed worth living we cannot consistently object to harms done to the animal before it was born. Utilitarians could argue that from an impersonal viewpoint we could say that for example a world with a group of dogs with welfare problems due to inbreeding is worse than a world without. However, this would only justify certain objections to interferences with animals. If enhancements would reduce the total amount of suffering in the world, a utilitarian would not object.

Robert and Baylis ( 2003 ) discuss the difficulties of demarcating species boundaries.

Johnson ( 1992 ), for example, argues that species have interests separate from its members, and he illustrates this by stating that while it is in the interest of a species (or more properly: population) of deer that weaker animals are killed by predators, this is obviously not in the interest of the individual animals that are killed. However, this does not show in itself that the species has a separate moral standing that is not derived from the moral standing of its members now and in the future.

In chapter “ The Flights of the Monarch Butterfly: Between In Situ and Ex Situ Conservation ” of this volume Marcel Verweij and I actually argue that there are collective dimensions to groups that exceed that of the aggregation of all the individuals of the group. However, these dimensions do not lead us to attribute direct moral status to groups.

What I am suggesting here is a type of biocentric outlook as Taylor ( 2011 ) has proposed. However, Taylor only considers individual natural entities to be morally relevant and my proposal would see ourselves not only as part of a group of individuals in nature, but as but one species between the species.

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Acknowledgments

I would like to thank Franck Meijboom, Frederike Kaldewaij, Aaron Simmons , and Joel Anderson for their helpful comments.

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Bovenkerk, B. (2016). Animal Captivity: Justifications for Animal Captivity in the Context of Domestication. In: Bovenkerk, B., Keulartz, J. (eds) Animal Ethics in the Age of Humans. The International Library of Environmental, Agricultural and Food Ethics, vol 23. Springer, Cham. https://doi.org/10.1007/978-3-319-44206-8_10

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killer whales and their trainers at Seaworld in San Diego

Orcas perform at SeaWorld San Diego in 2014. The mammals are highly intelligent and swim vast distances in the wild. Research has documented stress-related behaviors in captive orcas for decades.

Orcas don’t do well in captivity. Here’s why.

The marine mammals, stars of amusement park shows around the world, have long died before their time.

In January 2019, Kayla died. She was a 30-year-old killer whale living at SeaWorld Orlando. If she’d been living in the wild, she’d likely have lived into her 50s, and possibly as old as 80. Still, Kayla lived longer than any captive-born orca in history.

It’s not clear what she died from (SeaWorld hasn’t released the results of her necropsy, and by law is not required to), but her immediate cause of death may not tell us much anyway: Often orcas technically die of pneumonia or other opportunistic infections that take hold because the animal is already weak, shows a database of necropsy reports kept by the Orca Project Corp., a nonprofit organization made up of marine mammal experts that advocates against orcas in captivity.

Seventy orcas have been born in captivity around the world since 1977 (not counting another 30 that were stillborn or died in utero), according to records in two databases maintained by cetacean experts. Thirty-seven of them, including Kayla, are now dead. Only a handful of wild-caught orcas have lived past age 30. No captive-born orca yet has.

There are currently 59 orcas in captivity at sea parks and aquariums throughout the world. Some are wild-caught; some were born in captivity. A third of the world’s captive orcas are in the United States, and all but one of those live at SeaWorld’s three parks in Orlando, San Diego, and San Antonio. Lolita, a 54-year-old orca who was captured in 1970 in the waters off Washington State, lives alone at the Miami Seaquarium, in a pool with an open-top roof that’s less than twice the length of her body.

An orca named Kayla, pictured at SeaWorld Orlando in 2011, died in January 2019 at 30 years old. In the wild, the average life expectancy for a female orca is 50, and some live to be 80 or 90.

Another 10 wild-caught orcas are currently held in sea pens in the Russian far east while the government investigates their possible illegal capture. If they end up being sold to aquariums, likely in China, the global captive orca tally could jump to 69.

Whether it’s humane to keep orcas in captivity is subject to vigorous debate. They are highly intelligent, social animals that are genetically built to live, migrate, and feed over great distances in the ocean. Orcas, whether wild-born or captive-bred, cannot thrive in captivity, says Naomi Rose, a marine mammal scientist at the Animal Welfare Institute, a nonprofit organization based in Washington, D.C. It’s partly their sheer size. Orcas are massive animals that swim vast distances in the wild—40 miles a day on average—not just because they can, but because they need to, to forage for their varied diets and to exercise. They dive 100 to 500 feet, several times a day, every day.

For Hungry Minds

“It’s basic biology,” Rose says. A captive-born orca that has never lived in the ocean still has the same innate drives, she says. “If you have evolved to move great distances to look for food and mates then you are adapted to that type of movement, whether you’re a polar bear or an elephant or an orca,” says Rose. “You put [orcas] in a box that is 150 feet long by 90 feet wide by 30 feet deep and you’re basically turning them into a couch potato.”

Rose explains that a primary indicator for whether a mammal will do well in captivity is how wide their range is in the wild. The broader their natural range, the less likely they are to thrive in confinement. This is the same reason some zoos have been phasing out elephant exhibits.

We can recreate terrestrial environments somewhat—like a savanna for example, she says—but we can’t recreate an ocean. “Not one marine mammal is adapted to thrive in the world we’ve made for them in a concrete box,” Rose says.

Those who study and work with captive dolphins (orcas are the world's biggest dolphin species) argue that it’s not about space but about whether orcas are given enough enrichment and training to get adequate exercise and mental stimulation.

SIGNS OF SUFFERING

It’s really difficult to prove what specifically shortens orcas’ lifespans in pools, animal welfare specialists say. “The thing with captive orcas is that their health is largely shrouded in mystery,” says Heather Rally, a marine mammal veterinarian at the PETA Foundation. Only people who are employed by a facility keeping orcas actually get close to them, and not much of that information is made public.

But it’s clear, say welfare specialists, that captivity can compromise orcas’ health. This is evident in killer whales’ most vital body part: their teeth. A peer-reviewed 2017 study in the journal Archives of Oral Biology found that a quarter of all orcas in captivity in the U.S. have severe tooth damage. Seventy percent have at least some damage to their teeth. Some Orca populations in the wild also show wear and tear on their teeth, but it’s symmetrical and happens gradually over decades, in contrast to the acute and irregular damage seen in captive orcas. According to the study, the damage occurs largely because captive orcas persistently grind their teeth on tank walls, often to the point where the nerves are exposed. These ground-down spots remain as open cavities, highly susceptible to infection even if caretakers regularly flush them out with clean water.

This stress-induced behavior has been documented in scientific research since the late 1980s. Commonly called stereotypies—repetitive patterns of activity that have no obvious function—these behaviors, which often involve self-mutilation, are typical of captive animals that have little or no enrichment and live in too-small enclosures.

Orcas have the second largest brain of any animal on the planet. Like humans, their brains are highly developed in the areas of social intelligence, language and self-awareness . In the wild, orcas live in tight-knit family groups that share a sophisticated, unique culture that is passed down through generations, research has shown .

In captivity, orcas are kept in artificial social groups. A few captive orcas, like Lolita, live completely alone. Captive-born orcas are typically separated from their mothers at ages far younger than in the wild (male orcas often stay with their mothers for life), and are often transferred between facilities. Kayla was separated from her mother at 11 months old and moved between SeaWorld properties across the country four different times. The stress of social disruption is compounded by the fact that orcas in captivity don’t have the ability to escape conflict with other orcas, or to engage in natural swimming behaviors in pools.

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In 2013, the documentary film Blackfish laid bare the psychological toll of captivity, through the story of a wild-caught orca named Tilikum who had killed a trainer at SeaWorld Orlando. The film included testimony from former SeaWorld trainers and cetacean specialists, who argued that Tilikum’s stress directly led to his aggression towards humans (he'd previously killed another trainer at a non-SeaWorld park in British Columbia, Canada). Court records show that SeaWorld had documented, between 1988 and 2009, over 100 instances of their orcas being aggressive towards trainers . Eleven of those instances resulted in injury, and one in death. ( Read a Q & A with a former trainer who criticized SeaWorld for cruel treatment of orcas .)

Blackfish also included an interview with a former wild orca catcher, John Crowe, who described in detail the process of capturing juvenile orcas from the wild: the wails of babies trapped in the net, the distress of their family members that frantically crowded outside, and the fate of the babies that didn’t survive the catch. Those young orcas’ bodies were slit open, filled with rocks, and sunk to the bottom of the ocean.

A SEA CHANGE

The public reaction to Blackfish was swift and furious. Hundreds of thousands of outraged viewers signed petitions calling for SeaWorld to retire their orcas, or to shut down outright. Partner corporations like Southwest Airlines and the Miami Dolphins severed ties with SeaWorld. Attendance slipped, and its stock began a series of nosedives from which it’s never fully recovered. ( Read more: How far will the Blackfish effect go? )

“We were a fringe campaign. Now we’re mainstream. That happened overnight,” says Rose, who has been advocating for captive orca welfare since the 1990s.

Animal advocacy groups had for years tried to take legal action against the U.S. Department of Agriculture, tasked with implementing the federal Animal Welfare Act, for failing to properly monitor the welfare of animals kept in captivity for entertainment. Efforts had never been successful says Jared Goodman, deputy general counsel for animal law at the PETA Foundation, who has participated in many of the lawsuits.

But in 2016, things began to change. California made it illegal to breed orcas in the state. Six months earlier, SeaWorld, which has a park in San Diego, announced that it would be ending its captive orca breeding program altogether, saying its current orcas will be the last generation to live at SeaWorld parks. Although 20 orcas and many other cetaceans continue to live and perform at its facilities, the company increasingly focuses its marketing on its amusement park rides.

At the federal level, Congressman Adam Schiff, a Democrat from California, has repeatedly introduced a bill to phase out captive orca displays across the U.S . In Canada, a federal bill is poised to pass later this year that would ban all captive cetacean displays—not just orcas, but all dolphins, porpoises, and whales.

LOOKING FORWARD

But there’s the remaining issue of what to do with the 22 orcas in captivity in the U.S. and Canada if federal legislation shuts down captive facilities, or if captive facilities like SeaWorld agree to go one step further and retire their current orcas altogether. None of these animals could be released into the wild—they have become dependent on being fed by humans.

The Whale Sanctuary project , led by a group of marine mammal scientists, veterinarians, policy experts, and engineers, aims to establish large seaside sanctuaries for retired or rescued cetaceans. The idea is that the animals would able to live in cordoned-off habitats in the ocean while still being cared for and fed by humans. The group has identified potential sites in British Columbia, Washington State, and Nova Scotia. The logistics of making a sanctuary a reality will be complex, says Heather Rally, who is on the organization’s advisory board.

“We have sanctuaries for every other species,” she says. Despite the challenges, “it’s absolutely the time for a marine mammal sanctuary. It’s long overdue.”

The Whale Sanctuary Project hopes that they might eventually partner with SeaWorld in the rehabilitation process. SeaWorld opposes the concept of sea sanctuaries—referring to them as “sea cages,” and saying that environmental hazards and a radically new habitat would likely cause tremendous stress to their orcas and do more harm than good. SeaWorld has removed from its website a 2016 statement detailing its opposition, but a company representative confirms to National Geographic that SeaWorld’s position remains unchanged.

Although there appears to be some hope for the future of captive orcas in the West, in Russia and China, the captive marine mammal industry continues to grow. In Russia, the 10 recently-captured orcas languish in a small sea pen awaiting their fate. China now has 76 operational sea parks, with another 25 under construction. The vast majority of the cetaceans in captivity there were wild-caught and imported from Russia and Japan. ( Read: China's first orca breeding center sparks controversy .)

China “hasn’t had their Blackfish moment,” Rose says. But she is hopeful it will come, because she’s seen it come before.

“You would not have written this story ten years ago,” she says.

Rogue orcas are thriving on the high seas—and they’re eating big whales

Single orca seen killing great white shark for first time ever

Vengeance—or playtime? Why orcas are coordinating attacks against sailboats

Why are these orcas killing sharks and removing their livers?

$1,500 for 'naturally refined' coffee? Here's what that phrase really means.

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v.7(1); 2019

Chronic captivity stress in wild animals is highly species-specific

Clare parker fischer.

Department of Biology, 200 College Ave. Tufts University, Medford, MA 02155 USA

L Michael Romero

Lay summary:

A review that compares changes in body mass, glucocorticoid and sympathetic responses, and reproductive and immune function, in wild animals recently introduced into captivity to their wild counterparts. Conclusion is that captivity can be a powerful chronic stressor that may be possible to mitigate, but the impact is highly species-specific.

Wild animals are brought into captivity for many reasons—conservation, research, agriculture and the exotic pet trade. While the physical needs of animals are met in captivity, the conditions of confinement and exposure to humans can result in physiological stress. The stress response consists of the suite of hormonal and physiological reactions to help an animal survive potentially harmful stimuli. The adrenomedullary response results in increased heart rate and muscle tone (among other effects); elevated glucocorticoid (GC) hormones help to direct resources towards immediate survival. While these responses are adaptive, overexposure to stress can cause physiological problems, such as weight loss, changes to the immune system and decreased reproductive capacity. Many people who work with wild animals in captivity assume that they will eventually adjust to their new circumstances. However, captivity may have long-term or permanent impacts on physiology if the stress response is chronically activated. We reviewed the literature on the effects of introduction to captivity in wild-caught individuals on the physiological systems impacted by stress, particularly weight changes, GC regulation, adrenomedullary regulation and the immune and reproductive systems. This paper did not review studies on captive-born animals. Adjustment to captivity has been reported for some physiological systems in some species. However, for many species, permanent alterations to physiology may occur with captivity. For example, captive animals may have elevated GCs and/or reduced reproductive capacity compared to free-living animals even after months in captivity. Full adjustment to captivity may occur only in some species, and may be dependent on time of year or other variables. We discuss some of the methods that can be used to reduce chronic captivity stress.

Introduction

The tens of thousands of vertebrate species on this planet are adapted to every condition from the Arctic to the tropics and from the mountain tops to the ocean depths. For all species, the environment contains both predictable changes (e.g. day–night transitions or seasonal variation) and unpredictable, uncontrollable threats to homeostasis and survival ( Romero and Wingfield, 2016 ). Vertebrates have evolved a suite of defenses against the myriad unpredictable ‘shocks that flesh is heir to’ (Shakespeare, Hamlet , 3.1)—a set of conserved physiological responses known as the ‘stress response’. While the stress response can help an animal survive a threatening event, if noxious conditions are repeating or unrelenting two physiological changes take place. First, the reactive scope of the animal shrinks thereby decreasing the animal’s ability to cope ( Romero et al ., 2009 ). Second, the stress response itself can begin to cause physiological problems, a condition known as ‘chronic stress’. Even though there is no generally agreed upon definition of chronic stress or the time-frame of its onset, long-term stressor exposure or chronic stress, can lead to weight loss, immunosuppression, reproductive failure and psychological distress ( Sapolsky et al ., 2000 ). Because the stress response occurs when situations are perceived as threatening, regardless of whether the animal is experiencing physical damage, a drastic change of conditions can lead to symptoms of chronic stress even when the animal is unharmed. Consequently, when a wild animal is brought into captivity for the first time, symptoms of chronic stress can occur even though the physical needs of the animal are attended to.

In captivity, animals are provided with shelter and ample food. Nevertheless, captivity can often result in negative physiological outcomes, particularly for newly-captured animals. The conditions of captivity can be perceived as threatening, and if the perceived threat does not decrease, symptoms associated with chronic stress may result. The sources of stress in captivity are many, including cage restraint, human presence, an unfamiliar environment, and other, more subtle stressors, such as artificial light conditions (reviewed in Morgan and Tromborg, 2007 ). When wild animals are newly brought into captivity, it is frequently for research, conservation, agriculture (e.g. fisheries) or the exotic animal trade. To keep these animals healthy, symptoms of chronic stress should be minimized or eliminated. It is often assumed that with time, animals will adjust to captivity conditions and stress will disappear. Indeed, many animals seem to thrive in captivity. Unfortunately, many other species do not ( Mason, 2010 ). In this review, we surveyed the literature to answer the following two questions: do wild animals eventually adjust to captivity conditions? And if so, how long does the period of adjustment typically take? This literature survey exclusively addressed wild animals introduced to captivity and not animals born in captivity.

We focused on several aspects of physiology that may be particularly affected by long-term stressor exposure. The acute stress response involves many behavioral and physiological changes, including activation of two hormonal pathways. The adrenomedullary response occurs within seconds of the onset of a stressor ( Romero and Wingfield, 2016 ). The catecholamine hormones epinephrine and norepinephrine are rapidly released from the adrenal medulla. These cause an increase in heart rate, as well as an increase in muscle tone, an increase in blood pressure and other physiological and behavioral changes that enable an animal to survive a sudden stressor, such as a predator attack. The second hormonal response is initiated within minutes of the onset of a stressor, when a hormonal cascade triggers the synthesis and release of glucocorticoids (GCs)—steroid hormones that have wide-ranging effects on the body ( Romero and Wingfield, 2016 ). While baseline levels of GCs help regulate metabolism, increased levels trigger an ‘emergency life history stage’, ( Wingfield et al. , 1998 ), where resources and behaviors are directed towards survival of the crisis and away from long term investments. GCs have a strong impact on the immune and reproductive systems ( Sapolsky et al ., 2000 ). In this review, we focus on captivity’s effects on mass (one of the best-documented outcomes of chronic stress), GC concentrations and the immune, reproductive and adrenomedullary systems. We also document how the adjustment to captivity is impacted by time of year and how captivity effects persist after release. Finally, we discuss some of the ways that captivity stress may be mitigated.

We surveyed the literature and gathered studies that compared wild-caught animals as they adjusted to captivity. We conducted a literature search through Web of Science using the search terms ‘captivity’ and ‘stress’ and ‘physiology’ or ‘endocrinology’ and related words. Because many papers reported on aspects of the stress response on animals that were in captivity but did not examine the effects of captivity itself, we were unable to devise search terms that included the studies we were interested in but excluded other research on stress in wild animals. We therefore devised the following criteria to determine whether papers should be included: (i) wild species were brought into captivity and physiological variables measured over the days to months of adjustment to captive conditions OR (ii) wild-caught captive animals were compared to free-living conspecifics AND (iii) the total captivity duration was at least 3 days (we did not include the many studies that measure only the acute stress effects of capture in the first 30 min to 48 hours). We further excluded two broad types of studies. One, we excluded studies where we could determine that all captive animals were captive-bred, as we were specifically interested in how well wild animals can adjust to captive conditions when taken from the wild (though we included some studies where the origin of captive animals was unclear). Second, we excluded studies of wild animals undergoing rehabilitation because it is not possible to distinguish between responses to captivity and responses to clinical interventions in animals that were injured or sick at capture. Once we had created a list of papers, we also checked the cited references of these studies for any important works our search terms missed.

There are many studies that focused on behavioral changes in captivity. However, the variables measured can be quite species-specific and difficult to interpret in a context of stress. Although we recognize the importance of behavior for the welfare of wild animals (reviewed in McPhee and Carlstead, 2010 ), we limited our focus to studies that included some physiological measurements (e.g. weight changes, hormone concentrations or immune measurements).

We found little standardization in experimental design in the papers examining the effect of captivity on physiology. We visually summarize the four most common experimental designs in Fig. 1 . Many researchers compared animals that had been exposed to captivity (duration: 3 days to several years) to those that had not ( Fig. 1A ). In some cases, the free-living population was sampled when the captive population was initially captured. This was often the case in species where only a single blood sample could be drawn from an individual. In other studies, the free-living population was sampled entirely separately from the captive group. This was often the case for long-term captives, such as zoo-housed animals. Another common technique was to take a single pre-captivity sample and a single post-captivity sample on the same animal (duration of captivity 5 days to 3 months) ( Fig. 1B ). Other researchers used repeated sampling techniques—either sampling the same individual multiple times, or keeping different individuals in captivity for different durations before sampling. Some focused narrowly on the first few days of captivity ( Fig. 1C ), while others did not take a second sample until several weeks had passed ( Fig. 1D ). Furthermore, captive conditions varied between studies, with some studies bringing animals into closed indoor situations, whereas others placed captive animals into open outdoor pens. We considered each situation to represent captivity, but we were not able to contrast any differences in responses.

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Examples of experimental designs to assess the effects of captivity on a physiological variable (e.g. GC concentration) ( A ) Comparison of captive individuals to free-living populations. In some cases, the free-living samples were acquired at the same time that the study population was brought into captivity. In other designs, the free-living samples were taken from entirely different populations than the origin of the captive animals (e.g. comparing zoo-housed animals to wild conspecifics). ( B ) Each individual measured immediately at capture and again after a period of captivity (days to months). ( C and D ) Each individual measured immediately at capture and resampled at multiple timepoints. Some studies focused on the first few days, with sampling points relatively close together (C). Other studies may not have taken another sample until several weeks after capture (D).

We created summary figures for the trends we observed in weight, GC hormones and the immune system with respect to captivity duration ( Figures 2 – 4 ). To construct these, we tallied the total number of studies that reported on the variable for a particular time window and determined whether the variable was above, below or equal to what it was in a free-living population. If a single report showed two different patterns (e.g. males and females had different patterns or two species were reported in the same paper), each pattern of was included separately. Therefore, one ‘study’ might be included multiple times in the figure. This also holds true for reporting patterns in the literature in the text and in the tables—if one paper reported multiple patterns in different groups of individuals, it was included more than once in calculating percentages of studies and was given more than one line on the tables. We did not include studies in the figures if there were marked seasonal differences in one species (see Section 9 for seasonal differences).

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Weight change as a function of captivity duration. Data were collected from 35 studies listed in Table 1 , with studies counted multiple times if they measured multiple time points after introduction to captivity. The number of species that lost weight in captivity (relative to wild, free-living animals) decreased with captivity duration.

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Changes in neutrophil or heterophil (N or H:L) to lymphocyte ratio in captivity as a function of time. Data were collected from 19 studies listed in Table 4 , with studies counted multiple times if they measured multiple time points after introduction to captivity. The percent of studies that recorded elevated N or H:L ratio in captivity decreased with the amount of time spent in captivity.

Because most of the papers we collected did not report effect sizes, a formal meta-analysis was not possible. Consequently, we focused on qualitative differences.

Mass and body condition in captivity

After being brought into captivity from the wild, animals frequently experience a period of weight loss ( Table 1 ). In 64% of studies (23 of 36), there was a documented decrease in mass associated with captivity during at least the initial capture period. Weight loss in captivity is likely to be attributable to chronic stress. Captive animals are not calorically restricted (as long as they choose to eat), which is not always the case in the wild, and they are not likely to use as many calories because cage restraint limits the amount of exercise that an animal can get in a day. Experimentally induced chronic stress has been demonstrated to lead to weight loss in mammals (e.g. Flugge, 1996 ), birds (e.g. Rich and Romero, 2005 ) and fish (e.g. Peters et al., 1980 ). In fact, weight loss is the most consistently seen effect of chronic stress ( Dickens and Romero, 2013 ).

Mass changes with captivity in wild animals

1 No at-capture values—first measured at 2 months.

2 Low sample sizes at each time point.

3 Captive pups were rehabilitated after rescue.

4 Slight weight loss from Day 10 to Day 60.

5 Females did not reach at capture weight, but all spontaneously aborted or gave birth.

* Data from this paper were used to generate Fig. 2 .

In 39% of studies where animals lost weight (9 of 23), the animals eventually regained the weight they had lost. In some cases, weight loss may be very transitory and last only a couple of days. For example, North Island saddlebacks (a bird native to New Zealand) lost weight on the first day of captivity, but by Day 3, they had not only regained weight, they were heavier than they were at capture ( Adams et al ., 2011 ). Transitory weight loss may be related to adjustment to the captive diet and not to major physiological problems. In other species, it may take weeks or months to regain the lost mass. House sparrows lose weight by Day 5–7 of captivity ( Lattin et al ., 2012 ; Fischer and Romero, 2016 ). In a long-term study of the species, they did not regain the weight they had lost for nearly 5 weeks ( Fischer et al ., 2018 ). Similarly, female possums lost weight for 5 weeks before beginning to gain again, and although they were kept for 20 weeks, they never fully recovered their lost weight ( Baker et al ., 1998 ). In 61% of studies (14 of 23), weight that was lost was never regained, though the studies may not have been long enough for weight to stabilize.

In some cases, weight loss depended on the characteristics of the animal at capture. For example, female possums lost weight over the first 5 weeks of captivity but some males gained weight during that period ( Baker et al ., 1998 ). When curve-billed thrashers were captured, birds from urban environments had higher body condition than desert birds, but after 80 days in captivity, their body conditions had converged to an intermediate value ( Fokidis et al ., 2011 ). Captivity may impact individuals differently depending on sex, population of origin or other individual characteristics, including transitory physiological states. (See Section 9 for the effects of time of year on the ability to adjust to captivity.)

Weight loss was not the only pattern seen in captivity. In 17% of studies (6 of 36), animals gained mass above their starting condition. Some animals may benefit from the increased calories available in captivity and be able to maintain their weight. In other animals, however, ad libitum access to food and limits to exercise may cause them to become obese and face the myriad negative consequences of a high body mass or body fat content ( West and York, 1998 ). In a study of domesticated budgerigars, birds were given ad libitum food and confined to cages that limited exercise. High body mass at the end of 28 days correlated with more DNA damage ( Larcombe et al ., 2015 ).

We visually summarized the patterns of weight changes in Fig. 2 . We graphed the total percent of studies that showed weight gain, weight loss or no change in weight at different time points after introduction to captivity. There were no studies that recorded weight gain in the first day. Most weight gain seems to be reported at 15–28 days of captivity (38% of studies showed weight gain in that window). The percent of studies reporting weight loss decreased with increasing captivity duration, reflecting the fact that many studies show eventual regain of lost weight. This suggests that for many species where weight was lost, it would eventually be regained.

It is possible that seasonal fluctuations in weight may interfere with the assumptions that weight gain or loss is due to captivity. Captive ruffs and red knots have strong seasonal weight fluctuations in captivity associated with weight gain for migration and breeding ( Piersma et al., 2000 ). If semi-naturalistic conditions are maintained in captivity (for example, if the animals are exposed to natural day length or are housed outdoors), then they may continue to experience seasonal weight changes that are not due to overfeeding or to long-term stressor exposure.

Changes in GCs during the adjustment to captivity

One of the most common variables to measure when assessing the stress of captivity was GC concentrations. GC hormones (primarily cortisol in fish and most mammals; primarily corticosterone in reptiles, birds, amphibians, and rodents) are produced in the adrenal cortex, have multiple roles throughout the body, and can influence many other physiological systems. Acute stressors cause a transitory increase in GCs, which is eventually brought down by negative feedback. Long-term stressor exposure frequently results in changes in GC regulation, although the part of the GC response affected (baseline concentrations, stress-induced concentrations, or negative feedback) and the direction of the change are different in different species and circumstances ( Dickens and Romero, 2013 ).

GCs can be assessed in several ways ( Sheriff et al., 2011 ). The most common method is to measure circulating plasma GCs by taking a blood sample. The sampling procedure itself can cause an increase in GCs, so researchers usually try to acquire the first sample as quickly as possible—within 3 minutes of capture or disturbance is generally considered a good guideline ( Romero and Reed, 2005 ). In many studies, it was not possible for the researchers to meet this standard because of the difficulty of capturing and bleeding the animals. In addition, some papers were written before the 3-minute standard had been established. It is also possible to assess GCs through other means. Fecal samples can be collected to measure metabolized GCs. Fecal samples provide an integrated profile of GC secretion over several hours to several days, depending upon the species, and reflect both baseline GCs and acute stress events ( Wasser et al ., 2000 ). Fecal sampling is convenient for many species when rapid capture and blood sampling is impractical. If the first fecal sample is collected soon after capture, it will not reflect the stress of captivity and may be considered a good free-living reference. Some researchers also used urinary GC metabolites, particularly in amphibian species, where animals could be left alone in a container of water from which excreted steroids were measured.

The initial capture and handling of wild animals is expected to cause an increase in circulating GC levels (an acute stress response). While some researchers investigated captivity-induced changes in the acute stress response itself (e.g. taking a plasma sample after a standardized 30-minute restraint stress at capture and again after a period in captivity), others incorporated the acute response to capture in the same analysis as longer-term captivity effects (e.g. taking a sample at 0, 2, 6, 18, 24, 48 and 72 hours post capture). Because of the variety of different measures used, we focused particularly on the captivity effects on baseline and integrated GCs ( Table 2 ). However, we will also discuss the effects of captivity on the acute stress response and negative feedback of GC production ( Table 3 ). Some researchers looked for the effects of captivity at different times of year—we do not include those studies in our calculations or in Tables 2 and and3 3 (see Section 9 ).

Patterns of change in baseline and integrated GCs when wild animals are brought into captivity (this table does not include studies where the pattern was different in different seasons—those studies may be found in Table 6)

1 Cortisol results only.

2 No difference in GCs in females pre-breeding—GCs elevated in both sexes during breeding season.

3 Captive population may include some captive-raised individuals.

4 Blood sampling took longer in some samples.

5 GC spike in many animals during first 2 weeks, but then drops well below at capture levels.

6 GCs increased in non-calling toads, but sample sizes low.

7 Some animals treated with long-acting neuroleptic, which had no effect on GC levels, so values were pooled.

* Data from this paper are incorporated into Fig. 3 .

Patterns of change in stress-induced GCs and negative feedback with captivity in wild animals

1 SI GCs lower post captivity in early winter, but no change during any other time of year.

2 Outside of breeding season and molt.

3 During the breeding season.

4 During the post-breeding/molting season.

5 SI GCs higher post captivity in pre-breeding and breeding season, not in winter.

Captivity does not influence GCs in all species. In 17% (10 of 59) studies, there was no recorded difference in GCs during or after the captivity period compared to free-living levels. In most studies, however, captivity caused a change in baseline or integrated GCs. In 42% of studies (25 of 59), wild animals had increased GCs at the end of the capture period compared to concentrations in free-living animals (periods of 3 days to several years). Elevated GCs are traditionally interpreted as an indication that animals are chronically stressed. Experimentally induced chronic stress can often lead to elevated baseline GCs, although this is by no means a universal response ( Dickens and Romero, 2013 ). Adrenal hypertrophy may be an underlying mechanism explaining the long-term elevation of GCs. For example, long-term captivity led to increased adrenal mass in African green monkeys ( Suleman et al., 2004 ) and mouse lemurs ( Perret, 1982 ). In nine-banded armadillos, 6 months of captivity (but not 3 months) caused adrenal changes similar to those after a harsh winter ( Rideout et al., 1985 ) and in herring gulls 28 days of captivity led to adrenal lesions ( Hoffman and Leighton, 1985 ).

However, many studies that reported elevated GC concentrations at the end of the captivity period may eventually have shown decreased GCs had the study been carried out for longer. For example, house sparrows had elevated baseline GCs after 1–7 days in captivity ( Kuhlman and Martin, 2010 ; Lattin et al., 2012 ; Fischer and Romero, 2016 ). But when captive house sparrows were sampled repeatedly over 6 weeks of captivity, the high baseline GCs seen at Day 7 were dramatically reduced over Days 11–42 and approached at-capture concentrations in one study ( Fischer et al ., 2018 ), but did not decrease in another study ( Love et al ., 2017 ).

The duration of captivity in the studies we collected was quite variable, ranging from 3 days to several years. To consolidate the patterns from multiple studies with different sampling times, we graphed the percent of studies with elevated GCs (relative to free-living levels) against captivity duration ( Fig. 3 ). We expected the percent of studies with elevated GCs to decrease as captivity duration increased (as shown in Fig. 1C and D ). This pattern would indicate an adjustment to captivity conditions and is a typical a priori prediction in the literature. However, we found that 45% (5 of 11) of species continued to have elevated GCs after 3 months or more of captivity. This suggests that for many species, there is never a complete adjustment to captivity. It is also possible that a publication bias exists in the papers we collected. When researchers did not see a difference between long-term captives and free-living animals, they may have been less likely to publish, or perhaps included those results in other studies that did not appear in our literature searches. It is interesting to note that the fewest studies reported elevated GCs at around two weeks post captivity, the amount of time that many researchers allow for their study species to become acclimated to laboratory conditions (e.g. Davies et al., 2013 ; Lattin and Romero, 2014 ; McCormick et al., 2015 ).

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Change in baseline or integrated GCs as a function of captivity duration. Data were collected from the 47 studies listed in Table 3 that had a well-defined wild baseline value (i.e. plasma samples were collected within minutes of capture; fecal or urine samples were collected shortly after capture), with studies counted multiple times if they measured multiple time points after introduction to captivity. This figure does not include studies with seasonal effects on the GC response to capture.

The analysis in Fig. 3 contains data collected from many different taxa, study designs, etc. A more informative methodology to investigate how GCs change over time in captivity is to compare multiple timepoints within the same experiment. We found 38 studies that used repeated sampling. Researchers either repeatedly sampled individuals or captured many subjects at once and sampled them after different captivity durations. In study designs with repeated sampling, 42% of studies (16 of 38) showed an early increase in GCs followed by a decrease back to free-living levels (e.g. Fig. 1C and D , the a priori prediction for GC adjustment to captivity). Of the remaining studies, 32% (12 of 38) matched the pattern in Fig. 3 with no decrease in GC concentrations over time, 13% (5 of 38) showed decreased GC concentrations in captivity and 11% (4 of 38) reported no change in GCs whatsoever. When the expected peak and fall of GCs was observed, the timescale of adjustment to captivity varied. Baseline GCs in mouse lemurs returned to at-capture levels by Day 5 ( Hamalainen et al ., 2014 ) while the Fijian ground frog had elevated urinary GCs until Day 25 post capture ( Narayan and Hero, 2011 ).

In some studies with repeated measures designs, the researchers did not or could not obtain a sample that represented free-living animals. In these cases, the first sample could not be acquired until minutes, hours or even days after capture. In all nine studies where this was the case (see Table 2 ), initially high concentrations of GCs decreased over the study period in at least some animals. This is consistent with the pattern we expect for animals successfully adjusting to captivity: capture, handling and the initial transfer to captivity result in high GCs that decrease as the animal adjusts. For example, female brushtail possums were not sampled until days after their capture and transfer to captivity, but showed decreasing plasma GCs from week 1 to week 20 of captivity ( Baker et al ., 1998 ).

These studies on baseline GCs together demonstrate a pattern wherein approximately half of species appear to adjust to captivity. Although some species seem to take longer to acclimate to captive conditions than others, it appears that many species will eventually show a reduction in GCs after an initial peak. We see this pattern across taxonomic groups, in birds, fish, reptiles, amphibians and mammals. However, we should be careful to not interpret a reduction in circulating baseline GCs, fecal GC metabolites or urinary GCs as a complete adjustment to captivity or an elimination of chronic stress. Even when baseline GCs have returned to free-living levels, other aspects of the animals’ physiologies may be negatively impacted. For example, even though circulating GCs were only elevated for 1 day in African green monkeys, adrenal mass was almost doubled after 45 days in captivity ( Suleman et al ., 2004 ). Similarly, while it is tempting to conclude that elevated GCs are diagnostic of chronic stress, it should be kept in mind that baseline GCs have many functions in metabolism and energy use. A change of baseline GCs in captivity could merely reflect a change in energy requirements and not the physiological damage we associate with chronic stress. Furthermore, a reduction in GCs in captivity, as seen in 14% of studies (8 of 59), could be interpreted as a reduction in allostatic load or as the exhaustion of adrenal capacity.

Impact of captivity on acute stress response and negative feedback of GC production

Relatively few researchers have explicitly investigated the effects of captivity on the acute GC stress response (see Table 3 ). Of those that have, 65% (11 of 17) found no effect of captivity (captivity duration 5–80 days). The six studies that reported changes in stress-induced GCs showed changes in opposite directions. In two studies, stress-induced GCs were decreased in captivity, even though the captive periods of 9 days ( Dickens et al., 2009a ) and 1 year ( Romero and Wingfield, 1999 ) were quite different. In contrast, stress-induced GCs were increased in captivity in four studies over similar time frames. Three studies had animals in captivity for about a year ( Romero and Wingfield, 1999 ; Berner et al ., 2013 ; Quispe et al ., 2014 ), with 5–8 days in the fourth study ( Sykes and Klukowski, 2009 ).

The negative feedback of the GC response to stress, where high GC levels lead to the inhibition of GC production, is very important for the control of physiological stress ( Vitousek et al ., 2019 ). Although chronic stress has frequently been found to affect the negative feedback of GC production ( Dickens and Romero, 2013 ), we found only three studies that explicitly measured negative feedback strength in animals immediately at capture and after a period of captivity. In each case, animals were injected with a synthetic GC (dexamethasone) after mounting a stress response to stimulate maximum negative feedback. The strength of negative feedback increased slightly in house sparrows after 5 days of captivity ( Lattin et al ., 2012 ), but in the same species showed no change after 21, 42 or 66 days ( Love et al ., 2017 ). In contrast, negative feedback strength decreased after 5 days of captivity in chukar partridges but returned to its at-capture strength by 9 days ( Dickens et al ., 2009b ). This is an important aspect of stress physiology, one that is critical for the total amount of GC exposure, and warrants further study to determine whether it is impacted by the stress of captivity in many species.

Immune consequences of captivity

Stress has well-documented, but sometimes complex, effects on the immune system. In large part, these changes are due to the acute or long-term effects of elevated GCs on leukocyte populations. GCs can cause immune redistribution, moving lymphocytes out of the bloodstream and into the skin, spleen and lymph nodes, where they will be available in case of a wound ( Dhabhar and McEwen, 1997 ; Johnstone et al ., 2012 ). GCs can also cause proliferation or mobilization of neutrophils (most vertebrates) or heterophils (birds and some reptiles) ( Dale et al ., 1975 ; Gross and Siegel, 1983 ; Johnstone et al ., 2012 ). Together, these effects on leukocyte populations result in a change in the neutrophil or heterophil to lymphocyte ratio (N or H:L ratio) ( Dhabhar and McEwen, 1997 ; Johnstone et al ., 2012 ). A change in the N or H:L ratio does not necessarily mean that an animal’s immune system is hypo- or hyperactive. Instead, this acts as another metric similar to GC secretion. A long-term increase in N or H:L ratio, like a long-term increase in circulating GCs, can be an indication that an animal is suffering from chronic stress ( Davis et al ., 2008 ).

We summarized the 23 studies that reported leukocyte counts in Table 4 . Although the N or H:L is a useful metric, in some studies the researchers chose to report total number or percent of different leukocyte types without calculating or performing statistics on the relative abundances of neutrophils/heterophils and lymphocytes. In these cases, we inferred the direction (or presence) of change after captivity of the N or H:L ratio based on the changes in leukocyte counts or percentages that were reported. In two studies, only the total number of leukocytes was reported without further subdivision of leukocyte types. In 48% of studies (10 of 21), N or H:L ratio was elevated at the end of the measured captivity duration relative to its free-living value. 29% of studies (6 of 21) documented no change in N or H:L ratio over the study period. N or H:L ratio was decreased in 24% of studies (5 of 21). In one study (in the Fijian ground frog), the N:L ratio was elevated for 15 days in captivity, but then returned to wild levels by Day 25, resulting in no overall change ( Narayan and Hero, 2011 ). Kuhlman and Martin (2010) further investigated leukocyte redistribution to the skin in house sparrows, comparing Day 1of captivity to Day 30. They concluded that the changes in H:L ratio were not due to redistribution of leukocytes, at least in this instance. We summarized the overall patterns of N or H:L ratio compared to captivity duration in Fig. 4 . The number of studies reporting an increase in N or H:L ratio decreases with captivity duration. This suggests that many or most species do adjust to captivity, and an initially high N or H:L ratio may decrease given sufficient time.

Changes in leukocytes during captivity

Timeframe refers to the longest duration of captivity measured. WBC = total white blood cells; H = heterophils; N = neutrophils; L = lymphocytes; n.c. = not calculated (in this case, a count or percentage of heterophils or neutrophils and lymphocytes was measured in the paper, but H or N:L ratio was not directly compared. Presence/direction of change in the rctypes); ↑ or ↓ = higher or lower than free-living; – = no change from free-living.

1 Pattern only seen in rhinos translocated from high to low (not high to high) elevation.

2 Total WBCs and N:L ratio also compared to free-living wild populations of a similar species—there was no difference.

3 Comparison to values collected in another study and species (llamas and alpacas).

4 Circulating leukocytes and skin-infiltrating leukocytes were measured. See text for skin leukocyte patterns.

Some studies also reported the total leukocyte counts, sometimes without further subdividing them into classes. While decreased circulating leukocytes has been associated with stress (generally because of redistribution rather than destruction of cells) ( Dhabhar, 2002 ), there was no clear pattern with the number of leukocytes in captivity. 53% of studies (9 of 17) showed no change in total white blood cells compared to free-living animals by the end of the captivity period; 23.5% (4 of 17) showed a decrease in circulating leukocytes; and 23.5% (4 of 17) showed an increase (captivity duration 3 days to 1 year, see Table 4 ).

Importantly, neither total leukocyte numbers nor the N or H:L ratio provide a very strong indication of immune capacity. Some researchers have used more direct measurements of immune functionality. The bacterial killing assay is a way to determine how effectively fresh whole blood can eliminate bacteria. This assay has the advantage of determining the real effectiveness of the immune system against pathogens ( Millet et al ., 2007 ). In the cururu toad, whole blood was less effective at killing bacteria after 13 days of captivity ( de Assis et al ., 2015 ) and in two other toad species, killing capacity decreased by 60 but not 30 days ( Titon et al ., 2017 , 2018 ). Similarly, in red knots held in captivity for 1 year, whole blood was less effective at eliminating two Staphylococcus species than in wild living birds (though there was no difference in Escherichia coli elimination) ( Buehler et al ., 2008 ). In contrast, there was an increased proportion of E. coli killed after 3 weeks of captivity in house sparrows ( Love et al ., 2017 ).

Another way to measure immune responsiveness is by measuring a proliferative response against non-specific antigens. In some studies, this is done by culturing a sample of blood along with an antigen and quantifying cell division. In male brushtail possums, the proliferative response to the plant toxin phytohemagglutinin decreased over 20 weeks but increased by 1 year ( Baker et al ., 1998 ). In female possums, the proliferative response increased from 11 to 15 weeks in captivity, and then remained at that high level for at least a year ( Baker et al ., 1998 ). In another study in male brushtail possums, leukocyte proliferation to a Mycobacterium protein derivative increased after 4 and 6 weeks of captivity, but only when the animals were housed in high-density pens to create crowding ( Begg et al ., 2004 ). The proliferative response to phytohemagglutinin can also be measured in-vivo if PHA is injected into the skin and the degree of swelling is quantified. In zebra finches, there was no difference in the in vivo PHA response between newly captured birds and those held for 10 or 16 days ( Ewenson et al ., 2001 ).

Two studies have attempted to quantify the strength of the adaptive immune system in captivity. In red knots, plasma was plated with rabbit red blood cells. The degree of hemolysis and hemagglutination provided a measure of complement and natural antibody action. Hemolysis and hemagglutination were similar in wild and captive birds when they were measured at the same time of year, which suggests that the strength of the adaptive immune response is unaffected by captivity ( Buehler et al ., 2008 ). Conversely, newly captured killifish had a stronger response to antigen after immunization than 4–6-week captives, suggesting that the adaptive immune system was less effective after captivity ( Miller and Tripp, 1982 ).

Overall, there does not seem to be a single pattern for immune regulation with captivity. While captivity has been shown to repress immune function in some species (e.g. reduced bacterial killing in red knots and toads), in other species, the immune system may be hyperactivated. For example, in house sparrows, gene expression for pro-inflammatory cytokines was elevated in captive birds (2- and 4-week captives) compared to newly caught animals, which was interpreted as hyperinflammation in captive birds ( Martin et al ., 2011 ). Changes in the immune response with chronic stress are thought to be most strongly tied to GC release. However, the impacts of GCs on the immune system can be complex. In the short term, GCs typically induce an immune response, while they can be immunosuppressive over the long term, although these interactions tend to be context-dependent ( Dhabhar and McEwen, 1997 ; Martin, 2009 ). As the interaction between GCs and immunity is complex and context specific, and as the interaction of GCs to captivity can be complex as well (see Changes in GCs during the adjustment to captivity ), it is not currently possible to predict whether captivity conditions will result in appropriate or inappropriate immune activity. However, there has been limited work in this area.

Effects of captivity on the reproductive system

Captivity has well-documented negative impacts on reproductive biology. In many species, captive breeding for research or conservation purposes can be a challenge. Even the house sparrow, so commonly used as a model species, does not readily breed in captivity ( Lombardo and Thorpe, 2009 ). In 74% of studies (17 of 23), the transition to captivity resulted in reduced reproductive capacity in wild species ( Table 5 ). Note, however, that these papers do not cover an extensive literature on captive breeding, including in individuals who have spent decades in captivity or were born in captivity, which is beyond the scope of this review. Here, we focus only on those papers that studied reproductive capacity of recent captives (only within the first year) and that examined a mechanism for reduced reproduction. There was no obvious taxonomic pattern for species that had reduced reproductive ability in captivity compared to those that had no documented reproductive problems. Duration of captivity did not appear to be a factor either. In one study of water frogs, reproduction in both males and females were negatively impacted by only 3 days of captivity ( Zerani et al ., 1991 ), while in jack mackerel, reproduction was inhibited after a full year of adjusting to captivity ( Imanaga et al ., 2014 ).

Reproductive effects of captivity in wild animals (if multiple times of year were examined, only breeding season is included in this table)

1 Different photosimulation and social stimulation tested—maximal testicular regrowth (long days + females) still below wild, though in that group, T was the same as wild.

2 Vitellogenin levels recovered by E2 use.

3 T spikes during the first 24–48 hours of captivity, but decreases below at-capture levels.

4 E2 spikes during first hours of captivity, but quickly decreases below at-capture levels.

5 E2 higher in captive than wild.

6 There was a transitory increase in LH at around Weeks 1–3 that came back to at-capture levels in multiple experiments.

7 T lower in captivity, but only after egg-laying.

8 E2 spike in first 6 hours of captivity but then returns to at-capture levels.

Different researchers measured different variables for reproductive capacity. Many studies analyzed reproductive steroid hormones (primarily testosterone in males and estrogen and/or progesterone in females). However, other variables were also measured, including gonad size and development, behavior and gamete development. In house sparrows, Lombardo and Thorpe (2009) found decreased sperm production, reduced testes size and a change in beak color from breeding-season black to wintering brown after 3 months of captivity. Female anole lizards experienced a rapid decrease in plasma vitellogenin (a protein necessary for yolk production) followed by regression of developing follicles ( Morales and Sanchez, 1996 ). In electric fish, behavioral differences between males and females were reduced in captivity until they disappeared or even reversed. This occurred concurrently with decreases in testosterone and 11-ketotestosterone (a potent fish androgen) in males ( Landsman, 1993 ).

The reduction of reproductive capacity might be tied to GC levels. GCs can be powerful suppressors of reproductive steroids ( Sapolsky et al ., 2000 ). Prolonged GC exposure can lead to decreased production of testosterone or estradiol, which can then have downstream effects on gonad development, egg maturation, sperm production and behavior. In green treefrogs, a decrease in sex steroids was concurrent with an increase in GCs ( Zerani et al ., 1991 ). However, in black rhinos, males had suppressed fecal testosterone and females had suppressed fecal progestins even though GC levels were below free-living levels for most of the captivity period ( Linklater et al ., 2010 ).

Captivity did not always result in suppression of reproduction but in most studies that did not show an effect of captivity, reproductive hormones were the only variables measured. The only exception was in the brown treesnake, where 3 days of captivity did not affect either testosterone or ovarian development (both were very low in free-living and captive animals) ( Mathies et al ., 2001 ). However, another study in brown treesnakes found underdeveloped testes in males after 4–8 weeks of captivity ( Aldridge and Arackal, 2005 ). Captivity may affect sexual variables differently in males and females. For example, in water frogs held in captivity for 2 weeks, only males appeared to be negatively affected by captivity ( Gobbetti and Zerani, 1996 ), which is opposite what is typically expected.

Overall, it appears that captivity tends to have a negative impact on reproduction in most species. However, there are relatively few studies that specifically examine the reproductive physiology of newly-captured animals. Furthermore, given that many animals eventually do breed in captivity while others do not, it is not clear how long-lasting these impacts may be or why they impact some species more than others.

Adrenomedullary effects of captivity

The adrenomedullary arm of the stress response can be difficult to measure. Measuring epinephrine or norepinephrine in the blood is relatively straightforward, but these hormones increase within seconds of disturbance, meaning that acquiring a free-living baseline in a wild animal is difficult without substantial acclimation to human presence. We excluded most studies that measured epinephrine or norepinephrine, as sampling techniques between wild and captive animals differed in ways that would obscure the meaning of their results. For example, plasma norepinephrine under anesthesia (collected within 50 minutes) decreased over 19 months of captivity in rhesus macaques, though a free-living sample could not be obtained under the same conditions ( Lilly et a l., 1999 ), and captive-raised bighorn sheep had a higher epinephrine response to a drop-net capture technique than did free-living sheep, though they had similar norepinephrine responses ( Coburn et al ., 2010 ).

Recording heart rate is another way to infer activity of the adrenomedullary system ( Romero and Wingfield, 2016 ). Heart rate recordings typically involve the use of specialized and expensive equipment, but can give instantaneous updates on heart rate. In addition, scientists can measure heart rate variability, which gives a metric of how much relative control the sympathetic and parasympathetic nervous systems have over heart rate ( Romero and Wingfield, 2016 ). However, depending on the type of heart rate recording device, it may be impossible to obtain baseline free-living heart rates. Although several researchers have had success measuring heart rate in free-living animals (e.g. white-eyed vireos; Bisson et al ., 2009 ), to our knowledge, there has not yet been a study that directly compares heart rate in free-living and captive animals of the same species.

Heart rate has been measured in only a few species during the transition to captivity. In newly-captured bighorn sheep, heart rate during restraint and blood sampling decreased from Days 1–2 (when the animals were handled extensively and transported) until Day 14 (Franzman, 1970). The heart rate of newly-captured European starlings was high compared to birds held for more than a year in captivity but decreased to the level of long-term captives within 24 hours ( Dickens and Romero, 2009 ). The adrenomedullary response to captivity was slightly different in house sparrows. Daytime heart rate was elevated above 1 month captive levels for at least 7 days post-capture ( Fischer and Romero, 2016 ). These data led to a long-term repeated-measures investigation during the first 6 weeks of captivity ( Fischer et al ., 2018 ). Heart rate tended to decrease until Day 18, then plateaued. Furthermore, there was a more profound effect on the heart rate response to a sudden noise in the starling study. While long-term captives showed a robust increase in heart rate after a loud noise, a typical adrenomedullary response, newly-captured birds had a virtually eliminated heart rate response for at least 10 days ( Dickens and Romero, 2009 ). A reduction in the startle response (as demonstrated in European starlings) could have negative consequences for animals that are released from captivity into the wild ( Dickens et al ., 2009a ). The adrenomedullary response to sudden noises or other startling events is an adaptation that allows animals to survive sudden traumatic events, such as predator attacks or conspecific aggression. An impaired startle response could result in death if it persists after the animals are released from captivity.

Overall, there are few studies examining the effects of captivity on the adrenomedullary response. The patterns we see in European starlings and house sparrows are different—it does not appear that there is a consistent heart rate response to captivity in passerine birds, much less in all vertebrates. We believe this is an area ripe for future studies. As telemetry equipment becomes cheaper and more available, we hope to see more investigations into the adrenomedullary response to captivity and other stressors.

Effects of captivity on seasonality of hormone regulation

Some studies examined seasonal differences in the response to captivity. Table 6 shows that the time of year when animals are introduced to captivity can have a profound effect on hormonal changes. For example, baseline GCs might increase when free-living birds are in molt, decrease when free-living birds are breeding, and not change when free-living birds are captured during the winter or spring ( Romero and Wingfield, 1999 ). Furthermore, Table 6 indicates that there is no consistent pattern across seasons or taxonomic groups. The implications of these differences are currently unknown, but the season of capture might partly explain the large variation across studies summarized in Figs 2 – 4 . Understanding why there are seasonal differences in the acclimation to captivity would be an important contribution to this field.

Seasonal effects of captivity

Arrows indicate direction of change in captive animals relative to an established free-living level. Captive and wild measurements were taken at the same time of year. GCs glucocorticoids; T testosterone; E2 estradiol.

1 Delay in acquiring wild baseline.

Other physiological consequences of captivity

Some studies, primarily in marine mammals, reported the effects of captivity on thyroid hormone. Unfortunately, there is not a consistent impact. For example, one study of beluga whales reported that thyroid hormone decreased over the first few days of captivity, but increased to a long-term stable level by day 11 ( Orlov et al ., 1991 ), whereas another study reported that thyroid hormone decreased within the first few days and remained low throughout 10 weeks of captivity ( St Aubin and Geraci, 1988 ). Similarly, rehabilitated harbor seal juveniles held in captivity for 4 months had lower thyroid hormone than free-living juveniles ( Trumble et al., 2013 ). In contrast, long-term captive harbor porpoises had the same thyroid hormone levels as wild populations ( Siebert et al ., 2011 ) and in female brushtail possums, thyroid hormone was elevated from Weeks 6–13, the same period when the animals were regaining weight they had lost in captivity ( Baker et al ., 1998 ). Clearly, more work is needed to determine the effect of captivity on thyroid hormone regulation.

Anatomical changes may also occur in captivity. Mountain chickadees showed remarkable reduction in hippocampal volume after 4 months of captivity ( LaDage et al ., 2009 ), an effect mimicked by black-capped chickadees after 4–6 weeks in captivity ( Tarr et al ., 2009 ). In neither species was the telencephalon affected—the effect was localized to the part of the brain involved in location-based memory tasks. This effect persisted even when the environment was enriched to include memory tasks ( LaDage et al ., 2009 ).

Captivity can lead to various pathologies. In a histological study of mouse lemurs that died spontaneously in captivity, lesions in the kidney were strongly correlated with captivity duration and with adrenal size ( Perret, 1982 ). The investigator also concluded that cardiac disease may result from chronic adrenomedullary stimulation, although they did not measure hormone concentrations directly ( Perret, 1982 ). Similarly, herring gulls developed amyloid deposits in the blood vessels of their spleens after 28 days in captivity ( Hoffman and Leighton, 1985 ). There may be many more hidden anatomical changes resulting from captivity, but few studies have looked for them.

Finally, recent data indicates that captivity can have profound effects at the DNA level. Bringing house sparrows into captivity resulted in an approximately doubling of DNA damage in red blood cells ( Gormally et al ., 2019 ). The impact of this damage on the individual remains to be determined.

Amelioration of captivity stress

Captivity can cause a wide array of physiological changes in wild animals that are consistent with chronic stress and are likely to be detrimental to health. However, can anything be done to prevent these changes? Is there a way to protect animals from the negative consequences of captivity stress? While this is not an exhaustive review of the solutions that have been tried, we offer some ideas that have been attempted to relieve symptoms of chronic stress due to captivity conditions.

Adjusting the physical conditions of captivity may be one of the simplest ways to reduce symptoms of chronic stress. Transferal from outdoors cages to indoors cages led to reduced reproductive hormones and behaviors in long term captive European starlings ( Dickens and Bentley, 2014 ) and to weight loss and reduced immune function in water voles ( Moorhouse et al., 2007 ). Cage size and density are also important for the development of chronic stress. High density housing during the initial captivity period resulted in elevated GCs compared to low density housing in flounders ( Nester Bolasina, 2011 ) and wedge sole ( Herrera et al ., 2016 ). However, reducing density by caging animals individually can have negative consequences, particularly in social species. Housing brushtail possums in groups eliminated the infection, weight loss and mortality that were seen when the animals were caged individually ( McLeod et al ., 1997 ). In male brown headed cowbirds, adding a female to the cage (previously solo housed) resulted in reduced plasma GCs, as well as increased testicular regrowth in photostimulated males ( Dufty Jr and Wingfield, 1986 ).

Many animals benefit from the use of behavioral enrichments to reduce abnormal behaviors that develop in captivity (reviewed in Mason et al ., 2007 ). Enrichments have become standard practice in zoo environments and situations where animals are held long-term or bred in captivity. Enrichments consist of providing animals with the means and motivation to practice a full range of natural behaviors, such as foraging opportunities, exercise opportunities and places to bathe or dust bathe. Even in temporary or laboratory conditions, environmental enrichments can be relatively easy to supply. However, we were unable to find any papers where the physiological benefits of enrichment techniques were specifically tested in newly captured animals. Using these techniques to accelerate the adjustment to captivity would be an exciting avenue for future research.

Lighting conditions may be very important for visual species. European starlings show more behavioral signs of chronic stress under fluorescent lights with a low flicker rate than a high flicker rate ( Evans et al ., 2012 ), but the low flicker rate does not elicit a GC response ( Greenwood et al ., 2004 ). Ultraviolet-deficient lighting resulted in higher baseline GCs in European starlings, although immediately after capture, this stressor may be too subtle to make a difference compared with the other stressors of captivity ( Maddocks et al ., 2002 ). Temperature conditions should also be carefully considered, particularly for poikilotherms. Warm conditions during the initial transfer to captivity resulted in high mortality in sardines ( Marcalo et al ., 2008 ) and higher GCs in cane toads ( Narayan et al ., 2012 ).

Overall, by matching captivity conditions as closely as possible to conditions in the wild, with roomy cages, exposure to naturalistic lighting and temperature conditions and animal densities kept relatively low, many animals will be better able to adjust to captivity and may have reduced chronic stress as a result. However, naturalistic housing conditions may be impractical for many situations. Furthermore, some stressors associated with captivity may be unavoidable. For example, nearly any visual or auditory contact with handlers resulted in a heart rate increase in two red-shouldered hawks ( Patton et al ., 1985 ). Therefore, in some cases, it might be beneficial to use pharmaceuticals to reduce symptoms of chronic stress.

Tranquilizers or sedatives are perhaps the most obvious drug classes to consider using in newly-captured animals. However, these may not be particularly effective at eliminating chronic stress symptoms. A long-acting neuroleptic did not result in many physiological changes in newly-caught otters ( Fernandez-Moran et al ., 2004 ). Tranquilizers did not impact any physiological variable in newly caught impala ( Knox et al ., 1990 ) or red-necked wallabies ( Holz and Barnett, 1996 ), although they reduced behavioral agitation to human approach and handling in the later study. Similarly, a long-acting tranquilizer changed behavior but not heart rate response to human approach in captive wildebeest ( Laubscher et al ., 2016 ). The anxiolytic and sedative diazepam did not affect GCs, heart rate, heart rate variability or activity in house sparrows during the first week of captivity (unpublished personal data). Overall, tranquilizers and sedatives do not appear to have long-term physiological benefits in captive animals. However, they may be useful in the short term. For example, by reducing physical agitation, they may prevent animals from injuring themselves during transport (e.g. in nurse sharks being moved into captivity; Smith, 1992 ) or during necessary handling by humans (e.g. in red-necked wallabies; Holz and Barnett, 1996 ).

Another strategy for pharmaceutical reduction of symptoms of chronic stress may be to chemically block the hormones of the stress response. The chemical agent mitotane causes a reversible chemical adrenalectomy, which drastically reduces circulating GCs ( Sanderson, 2006 ). In house sparrows treated with mitotane immediately upon capture, baseline and stress induced GCs were drastically reduced during the initial captivity period, but recovered to the level of untreated birds by Day 10 of captivity ( Breuner et al ., 2000 ). We investigated the effects of mitotane treatment during the first 7 days of captivity in house sparrows and found that it reduced resting heart rate even when it did not cause the expected dramatic decrease in GC (unpublished personal data). The adrenomedullary response can also be pharmaceutically reduced by blocking the receptors of epinephrine and norepinephrine. We used alpha- and beta-blockers (which interfere with binding of epinephrine and norepinephrine to their receptors) during the first week to block chronic captivity stress in house sparrows. We found that while the beta-blocker propranolol had no effect on heart rate, it did prevent the increase in baseline GCs that we typically see in newly-captured members of this species ( Fischer and Romero, 2016 ).

The persistence of captivity effects after release

The physiological changes caused by captivity can persist even after animals have been released back into the wild. Chukar partridges that were held in captivity 10 days and then released to a new location than where they had originated had lasting changes to their GC regulation (decreased negative feedback for at least 30 days, Dickens et al ., 2009a ). Red foxes that were kept in captivity for 2 to 8 weeks were less likely to establish a stable territory upon release than foxes that were caught and immediately released ( Tolhurst et al ., 2016 ). River otters kept in captivity for 10 months had lower survival than otters not kept in captivity ( Ben-David et al ., 2002 ). The captivity effect was strong enough that crude oil ingestion (mimicking the state of oiled otters in rehabilitation) had no further effect on survival ( Ben-David et al ., 2002 ). Rehabilitated barn owls ( Fajardo et al ., 2000 ) and guillemots ( Wernham et al ., 1997 ) had much shorter life expectancies than wild birds.

However, captivity may not necessarily have lasting negative impacts. In Grevy’s zebra, fecal GC metabolites were elevated in captivity, but decreased back to the wild norm quickly after release ( Franceschini et al ., 2008 ). Similarly, released Eastern Bettongs decreased GC metabolites after release from a period of over 30 days of captivity ( Batson et al ., 2017 ). Hermann’s tortoises kept in captivity for 2–8 years following an injury showed no difference in movement, thermoregulation or body condition compared to free-living animals after release to the wild ( Lepeigneul et al ., 2014 ). Captivity up to 3 months did not affect survival in Stellar’s sea lions ( Shuert et al ., 2015 ). Captivity may even have positive effects in some cases. For example, hedgehogs were more likely to survive a translocation event if they were held in captivity for greater than 1 month compared to those held <6 days ( Molony et al ., 2006 ).

Whether an animal will be permanently negatively impacted by captivity or not may depend on the captivity conditions, species, time of year, method of release or individual effects. Wild rabbits held for 2, 4, 6 or 8 weeks in quarantine before release did not differ in survival probability ( Calvete et al ., 2005 ). In another study in that species, GCs did not change over the course of a quarantine period, but animals with higher plasma and fecal GCs were more likely to survive, even though they had worse body condition ( Cabezas et al ., 2007 ). Saddlebacks were more likely to survive post-release when they had a robust GC response to a standardized acute stressor ( Adams et al ., 2010 ). Therefore, captivity may have more profound effects on survival if it negatively and permanently changes GC regulation.

Conclusions

Captivity can cause weight loss, persistent changes in baseline and integrated GCs, changes in the immune system and reproductive suppression. These effects can last for months or years in some species, indicating that some species may never truly adjust to captivity conditions. The welfare implications of chronic captivity stress are obvious, and zoos and other institutions that hold animals in captivity long-term generally have strategies in place to minimize captivity stress. Breeding facilities (for conservation, research and agriculture/fisheries) are particularly invested in reducing chronic captivity stress, given its profound impact on the reproductive system. Figure 3 indicates that many species may continue to have elevated GCs months or years after capture, while Figs 2 and and4 4 suggest that most animals will recover from the weight loss and elevated N or H:L ratios caused by the initial transfer to captivity. Given that weight loss and changes to N or H:L ratio are affected by GCs, it is possible that with continuing high GC concentrations, sensitivity to these hormones decreases in captive animals. The reproductive system tends to be negatively impacted by captivity, presumably because of elevated GC hormones. The negative effects of captivity are species-specific, some species adjust to captivity while others do not (see also Mason, 2010 ).

A captive animal may be physiologically quite different than a wild animal ( Calisi and Bentley, 2009 ). Therefore, the confounding effects of captivity must be considered in physiological studies using captive wild animals, even when stress is not the focus of research. Animals that are held in captivity for research might respond quite differently to a range of experimental treatments than a wild, free-living individual would. For example, environmental contaminants had different effects on wild and captive sea otters ( Levin et al ., 2007 ), and experimentally induced chronic stress caused a change in fecal GCs in free-living but not captive European starlings ( Cyr and Romero, 2008 ).

The existing literature indicates that the effects of captivity on physiology are inconsistent. Some of the differences between animals that adjust and do not adjust to captivity might be explained by life-history features of the different species (see Mason, 2010 ). For example, captive predators that have large ranges in nature tend to show more behavioral anomalies and more infant mortality than those that naturally have smaller ranges ( Clubb and Mason, 2003 ). However, it may be possible to improve the physiological outcome for newly-captured animals by adjusting the season of capture, improving and enriching housing, allowing for an appropriate adjustment period, and possibly by the careful use of pharmaceuticals. Captivity stress will continue to be a factor in captive animal research, and the conditions, timing and duration of captivity must be considered as experiments are designed and interpreted.

Unfortunately, the results of this literature review do not suggest useful overall and/or generalized guidelines to wildlife managers. The overall picture is that wild animals acclimate to captivity in a highly species-specific manner. However, the most important conclusion from this review is that collecting multiple measures of physiology, rather than restricting studies to a single measure (e.g. GC concentrations), will provide a better picture of how well an individual or species is, or is not, coping with introduction to captivity.

This work was supported by the U.S. National Science Foundation [grant number IOS-1655269 to L.M.R.].

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Essay on Zoo for Students and Children

500 words essay on zoo.

The world is a huge place to see. It consists of so many living organisms that it is impossible to see each and every one of them. Especially for human beings, who are fascinated very much by animals. For the same reasons, zoos were created so that humans can interact better with animals.

In other words, a zoo is a facility that has animals, birds, and reptiles of all kinds. They are confined to space where they are given food and medical facilities. The government has given strict guidelines to maintain a zoo. This is done keeping in mind the animal’s safety. In addition, zoos are made breeding grounds for animals to protect their species.

Benefits of Zoo

Zoos were made to bring wildlife closer to humans. It gave humans a better and up-close view of them. This allows various researchers and scientists to note the behavioral pattern of the animals. It helps them in their studies and discover new things.

In addition, zoos are a great source of entertainment for kids. They love visiting zoos and interacting with animals. This helps them learn practical knowledge about the animal. It also gives them exposure to wildlife and widens their knowledge.

Furthermore, zoos give us easy access to rare animals. Had it not been for zoos, we would have never been able to see what some animals looked like. We enjoy their behavior and it also creates awareness about the extinction of the rare species.

Similarly, zoos are a safe breeding ground for animals. They ensure the animal breeds so they never go extinct. This helps in creating a good balance. Moreover, the zoos ensure the animals get all the nutrition in their bodies to lead a healthy life. This is beneficial as the animal may not get guaranteed meals in the forests.

Get the huge list of more than 500 Essay Topics and Ideas

Disadvantages of Zoo

While the zoo is a great place for entertainment, it is also very exploitive. It takes advantage of the poor animals to make a profit off them. The zoos keep animals in very bad conditions. It takes unethical methods just to create revenue.

Furthermore, zoos are very unfair to animals. They take the animals out of their natural habitats just for the sake of human entertainment. Why would the animals be put into cages as humans want them to? They are voiceless creatures who are being forced to live in poor conditions. Imagine putting humans into cages so animals could come to see them. It sounds inhumane the other way around but not when we do the same to animals.

Most importantly, zoos do not take proper care of exotic animals. They bring them over in their facility despite knowing that they cannot survive in that climate. Some zoos do not take enough precautionary measures to keep the animals safe. This has resulted in so many deaths of animals that it seems cruel.

In short, though zoos are very helpful to humans and animals to an extent. They must be monitored constantly to ensure the animals are safe. The unethical zoos must be shut down at once to prevent any further loss of animals.

FAQs on Zoo

Q.1 List the advantages of Zoo

A.1 Zoos bring the wildlife close to humans. It helps researchers study them closely and discover new things. It protects rare species and provides a safe breeding ground for them as well.

Q.2 How are zoos harmful to animals?

A.2 Zoos are very harmful to animals. They take them out of their natural habitat for human entertainment. They make them stay in poor conditions due to which they also lose their life and get infections.

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COSTA RICA'S LEADING ENGLISH LANGUAGE NEWSPAPER

Exchange Rate Crisis Hits Costa Rica’s Banana Sector

Power outages scheduled by ice across costa rica, president chaves’ legislative address: a tale of two costa ricas, costa rica may gardening: tips and tricks for a bountiful harvest, costa rica drops in world press freedom index 2024, costa rica shuts down state zoos, ends animal captivity.

The government of Costa Rica announced this Thursday that it will close the country’s two state zoos, following 11 years of litigation over a law that in 2013 prohibited keeping wild animals caged in captivity. The Ministry of Environment and Energy (Minae) indicated that “the contract with the Fundazoo Foundation, which expires this Friday and managed the two state zoos, one in the heart of the capital and another on the outskirts of the city, will not be renewed.”

“The animals that will be recovered from the state zoos will be transferred to the rescue center known as SOAVE,” said José Pablo Vázquez, a conservation area official at Minae.

Both facilities should have been closed in 2014, following the approval of the law, but various judicial appeals regarding the concession delayed the closure for a decade.

The Simón Bolívar Zoo in the center of San José has 374 animals of 56 different species. The San Ana Conservation Center has 26 animals from seven species.

These 400 animals under the care of the Foundation will be “recovered” by the government, which did not say what it will do with them.

“This transfer is being carried out so that all these animals can be examined, assessed, and undergo the necessary veterinary clinical examinations,” commented Vázquez. Following the examinations, their final destination will be decided, added the Minae expert.

In Costa Rica, there will no longer be any more zoos with caged animals. However, there is a private park in the northern city of Liberia, where visitors go on safari in vehicles to observe the animals. There are also animal rescue centers.

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By Jesus Jiménez

Costa Rica announced last week that it would close its two remaining state zoos, more than a decade after it passed a law to ban keeping wild animals in government-sponsored captivity but was met with legal blowback.

Costa Rica’s Ministry of Environment and Energy said in a statement on Saturday that it would not renew its contract with Fundazoo, a foundation that had run the zoos. The move will close the country’s last two state zoos: the Simón Bolívar Zoo and the Santa Ana Conservation Center.

State officials last week began transferring 287 animals from the two facilities to a rehabilitation center, where the health of the animals will be evaluated to determine what environment will best suit them. Some of the animals have been in captivity for more than 30 years, the ministry said.

Franz Tattenbach, the minister of environment and energy, said on Saturday that Costa Rica would move toward running sanctuaries for animals that cannot return to to the wild.

“Captivity is only justified when animals cannot return to the forest for either physical or behavioral problems that prevent them from living in freedom,” Mr. Tattenbach said in Spanish in a video on Facebook . “This closure consolidates Costa Rica’s vision of wildlife protection.”

The move not to renew Costa Rica’s contract with Fundazoo, closing the country’s public zoos, came more than a decade after Costa Rica passed a wildlife protection law in 2013 that banned keeping wildlife in captivity. Costa Rica’s state run zoos were supposed to close in 2014, but the law was met with legal appeals by Fundazoo, which delayed closing the public zoos, according to the FAADA Foundation, an wildlife nonprofit.

“The closure of the state zoos is a very important step forward,” FAADA said in a statement . “We join in the celebration of this historic achievement.”

The law does not apply to 18 private zoos in Costa Rica, according to FAADA.

Fundazoo did not respond to requests for comment on Tuesday.

José Pablo Vásquez, a biologist with a government group that oversees conservation efforts, said in a statement on Saturday that an inventory had been taken of the animals removed from the two zoos and they were being evaluated by teams of biologists and veterinarians.

Mr. Tattenbach said that animals would be placed in a quarantine before teams determined whether they could be reintroduced to the wild or if they would be best taken care of at a sanctuary. Some animals had yet to be transferred out of the zoos as of Tuesday, including an alligator and some turtles, the ministry said.

Dr. Darryl Heard, an associate professor of zoological medicine at the University of Florida, said that in some instances, it could take years before animals were ready for the wild, and that some animals might not be able to return to the wild at all.

“If they’ve been away from the wild or if they were captive-born, then they’ve not been able to develop necessarily the skills to feed themselves, protect themselves from predators and so forth,” Dr. Heard said.

Dr. Alonso Aguirre, dean of the Warner College of Natural Resources at Colorado State University, said that some animals can struggle returning to the wild, noting how Keiko, the whale featured in the movie “Free Willy ,” had died after being released.

“So many of these animals, the only thing they know is captivity,” Dr. Aguirre said.

Costa Rica could set an example for other countries on how to move away from zoos, while keeping some species safe, he said.

“We have to get away from captivity,” Dr. Aguirre said. “I think that’s a huge lesson for the world. If Costa Rica can do it, everybody else can.”

While some wildlife advocates in North America have called for closing zoos, Dr. Heard said that it was a “very complex issue” that should focus on animal conservation.

“I know that there are things that still need improvement,” Dr. Heard said of zoos. “But there’s generally been a positive trend in remediating those issues.”

Jesus Jiménez covers breaking news, online trends and other subjects. He is based in New York City. More about Jesus Jiménez

New film shows the toll Russia’s invasion has taken on animals in Ukraine

John Yang John Yang

Rachel Wellford Rachel Wellford

Harry Zahn Harry Zahn

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Copy URL https://www.pbs.org/newshour/show/new-film-shows-the-toll-russias-invasion-has-taken-on-animals-in-ukraine

The war in Ukraine has upended the lives of millions of people. It’s also disrupted the lives of an untold number of animals, both pets and zoo animals. An upcoming episode of Nature on PBS, “Saving the Animals of Ukraine,” documents how war-torn Ukrainians are reclaiming humanity by rescuing animals. John Yang speaks with director Anton Ptushkin about the film.

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Notice: Transcripts are machine and human generated and lightly edited for accuracy. They may contain errors.

The war in Ukraine has upended the lives of millions of people. It's also disrupted the lives of an untold number of animals, both pets and zoo animals. Some were left for days without food or water traumatized by the sounds of war.

Next, Wednesday's episode of PBS's Nature is called Saving the Animals of Ukraine. That tells how war torn Ukrainians are reclaiming a bit of their humanity by rescuing animals. Earlier I spoke with the director Anton Ptushkin about how the film came about.

Anton Ptushkin, Director, "Nature: Saving the Animals for Ukraine": That was February 2022. And it was just the beginning of the full scale invasion from Russia side. And, you know, there was a vast majority of photos and videos with people from Ukrainian trying to save themselves and their animals. And we were so moved by this foolish, you know, because it was some kind of light of hope, and meets this dark time. So we decided to just develop this topic and eventually, you know, made a documentary.

You show us a lot of stories about many animals, some of them very tragic, some of them happier. One of the happier ones is about the Jack Russell Terrier named Patron started out as the pet for a young boy and now is actually serving his country in a way of enlisted into the war effort. Tell us about Patron and what he's doing

Anton Ptushkin:

Basically he's sniffing the bombs. And for me, the story is like speaks speak volumes because Parton was just a regular dog, you know, he just wants to play and just walk but because his father, you know, dog parent, Michael, he's a Colonel of engineer troops of Ukraine. He is looking for the mines. So that's why Patron's starts looking for the mines as well.

Eventually, this dome become like a symbol of resilience of Ukraine. And he become, I believe, for the first time in history of UNICEF, he become like, Good Will Ambassador dog.

You also show us animals who have been severely traumatized I think of the lion named Bretzel. He lived through a Russian missile barrage and keep telling us a little bit about him.

Yeah, it turned out that animals they almost share the same suffering as people. And the story of poor lion who was being kept in a cage in Donetsk region which is almost like a front line. And he was bombarded, you know, this area was bombarded many times and these poor lion he had like, severe symptoms of PTSD. He was trying to break away the cage and he smashed his face against the cage.

So eventually he was immigrated to the Spain and to the place that we can call, like, let's say Animal Rehabilitation Center. And he completely recovered. You wouldn't believe like this is completely normal lion right now. And I remember him like a year ago. And he was just roaring, you know, every time when you come close to the cage, but right now he's completely recovered.

There were other powerful stories that you told about animals that went long periods of time without food or water Shafa, a cat that was stranded on the seventh floor of a building for 60 days, the rest of the building had been destroyed. And you spoke with producer Kate Parunova, who was one of the first to spot Shafa?

Kate Parunova:

I came to them and said, Look, guys, I'm so grateful that's having so much disaster and misery around you right now with people, you find time to help animals in such cases. And he replied to me, we don't care if it's an animal or a human being, we're Rescue Service, and every life matters to us. I mean, that was a point when you just start crying.

You know, Anton, earlier you talked about these stories illustrating hope and dark times. What do you think these stories say about the spirit in the character of the Ukrainian people in this dark time of war?

You know, for me, all these documentaries, about people about resilience and about the moral aspects of Ukrainians, you know, because, as one of the main tenants of our documentary said, like, your attitude towards animals is basically your attitude towards people, you start to save animals, and then animals save you, because they help you drastically, you know, just to cope with the stress and those stories. I mean, they really bring us some hope.

As you may know, there was controversy in the United States about continued aid to Ukraine in this war effort. Are you hoping that this film will remind people in the United States around the world that this is still going on that Ukraine still needs help and aid?

Yes, that's, that's my dream, actually. And I just came back from Ukraine, and a couple days ago, I lost my friend in this horrible war. Unfortunately, you know, these stories, we, people of Ukraine that we become kind of get used to. I mean, it's — it may sound cynical, but we get used to such stories, but I believe that people are America, people in the world. After watching this documentary, yeah, they feel, you know, this idea that the war is to go in and we don't need to forget about those horrible events that are going in my country.

filmmaker, Anton Ptushkin, we are very sorry for your loss. And thank you for your time today.

Thank you. Thank you for having me.

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John Yang is the anchor of PBS News Weekend and a correspondent for the PBS NewsHour. He covered the first year of the Trump administration and is currently reporting on major national issues from Washington, DC, and across the country.

Rachel Wellford is a general assignment producer for PBS NewsHour.

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COMMENTS

How Does Captivity Affect Wild Animals?
Romero emphasized the same point in a 2019 paper: the effect of captivity is, ultimately, "highly species-specific.". In many ways it depends on the complexity of each species' brain and social structure. One decent rule of thumb is that the larger the animal, the worse it will adjust to captivity. Thus the elephant and the cetacean ...
Animals in Captivity Essay
I will be specifically using lions in my examples throughout, however, my examples can be compared to most other animals in captivity. First of all, keeping animals in captivity is unnatural. It's smoke and mirrors people, IT'S A LIE! The animals are more bored than a 6-year-old kid on a Sunday at church.
Opinion
The first zoos housed animals behind metal bars in spartan cages. ... A 2018 analysis of the scientific papers produced by association members between 1993 and 2013 showed that just about 7 ...
Persuasive Essay On Animals In Captivity
Persuasive Essay: Why Zoos Are Good For Animals 956 Words | 4 Pages. Zoos have always been something that families love and kids look forward to going to. Kids learn about the animals and the habitats and enjoy the entertainment. It is a great experience for people, but not for the animals. Zoos are downright cruel to Animals.
Mistreatment of Wild Animals in Captivity
A: Wild animals are those who belong to a species that is adapted to live outside of captivity, whether or not they were born in captivity. In contrast, domesticated animals, such as pets and farm animals, have been selectively bred over a very long period of time for milder temperaments and for the ease of human handling. 22, 23 Research shows that even after generations spent living and ...
Essay on Animals in Captivity
Essay On Animal Captivity. 780 Words; 4 Pages; Essay On Animal Captivity. The issue on whether or not to keep animals in captivity has been debated heavily for a long time. With species such as the panda on the verge of extinction to mistreatment of marine mammals in theme parks such as Sea World, keeping wild animals under the care of humans ...
Should Animals be Kept in Captivity: an Ethical Dillema
The question of whether animals should be kept in captivity requires careful consideration of multiple factors, including conservation, education, and ethics. While captivity can contribute to conservation efforts and provide. educational opportunities, the ethical concerns surrounding animal welfare cannot be ignored.
Animals in Captivity: Ethical Dilemmas
The ethical dilemma surrounding animals in captivity centers on the tension between animal welfare and conservation objectives. While some argue that captivity can play a role in species preservation, it is essential to scrutinize the conditions in which animals are held and the impact on their well-being. 1. **Animal Welfare:** The confinement ...
Ecological Ethics in Captivity: Balancing Values and Responsibilities
The presumption that the keeping of animals in captivity in zoos and aquariums is morally acceptable has long been questioned by animal rights-oriented philosophers who believe that such facilities by definition diminish animals' liberty and dignity as beings possessing inherent worth (e.g., Jamieson 1985, 1995; Regan 1995). Such critiques ...
Introduction: The Ethics of Captivity
The final set of essays detail the harm produced by the captivity of nonhuman animals who are known to be intellectually, emotionally and socially sophisticated. Catherine Doyle's "Elephants in Captivity" summarizes the critical discoveries about elephants that show why life in zoos and circuses is ethically indefensible.
Argumentative Essay: Is Keeping Animals In Captivity Wrong?
Don't keep animals in captivity, and stop animal abuse. In captivity, animals are extremely distressed after being moved into the enclosure. Confined, many develop behaviour problems (zoochosis) that are described as "self-harming", "insane" and "scary". According to a study conducted by the Captive Animals' Protection Society ...
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Free【 Essay on Animals in Captivity 】- use this essays as a template to follow while writing your own paper. More than 100 000 essay samples Get a 100% Unique paper from best writers.
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Wild vs. Captivity. In The Wild. In Captivity. Cetaceans can travel up to 100 miles daily, feeding and socializing with other members of their pods. Pods can contain hundreds of individuals with complex social bonds and hierarchies. Cetaceans are housed in small enclosures, unable to swim in a straight line for long or dive deeply.
Why Wild Animals Should Be Conserved in Captivity
Firstly, wild animals are better conserved in captivity as their safety from external threats can be guaranteed. One major threat most animals face is the destruction of their habitat, which is often caused by human activity. For example, the Spix's macaw, more famously known as the bird from the Disney movie, Rio, has been classified as ...
Marine mammals in captivity
The monotonous, confined life of animals in captivity is a mere shadow of what life was like for them in the wild. The Humane Society of the United States believes that animals in bare tanks do not present a realistic image of natural behaviors or natural habitats. Marine mammals are best protected by cleaning up and protecting their habitats.
Animal Captivity: Justifications for Animal Captivity in the Context of
The central question of this chapter is whether keeping animals in captivity is morally justified. Captivity could be considered inherently wrong when animals are perceived to have an interest in liberty. ... Consciousness: essays from a higher-order perspective: essays from a higher-order perspective. Oxford: Oxford University Press. Book ...
Orcas don't do well in captivity. Here's why.
Orcas, whether wild-born or captive-bred, cannot thrive in captivity, says Naomi Rose, a marine mammal scientist at the Animal Welfare Institute, a nonprofit organization based in Washington, D.C ...
Research essay- animal captivity
Animal Captivity Essay In the past decade there have been many arguments and court cases for animal captivity to change. Such arguments are "Why are animals locked up?" or "Why do people own animal rights?". All those questions always go to court to get a final answer to help find a change. A few familiar court cases are the seaworld ...
Chronic captivity stress in wild animals is highly species-specific
We found little standardization in experimental design in the papers examining the effect of captivity on physiology. ... Three studies had animals in captivity for about a year (Romero and Wingfield, 1999; Berner et al., 2013; Quispe et al., 2014), with 5-8 days in the fourth study (Sykes and Klukowski, 2009).
Essay on Zoo for Students and Children
Q.1 List the advantages of Zoo. A.1 Zoos bring the wildlife close to humans. It helps researchers study them closely and discover new things. It protects rare species and provides a safe breeding ground for them as well. Q.2 How are zoos harmful to animals? A.2 Zoos are very harmful to animals.
Argumentative Essay About Animal Captivity
Animal captivity means the state or period of being held, imprisoned, enslaved, or confined. Animal captivity is a worldwide issue. Places all around the world keep animals in captivity, whether it is for an elephant's ivory, to keep from endangerment, or for the entertainment business. Animals need to be kept in their natural environment ...
Captive Animals: Perspectives, Practices, Challenges and Ethics
This Special Issue is designed to collate articles pertaining to the challenges and practice of ethically keeping animals in captivity and will include topics such as: animal ethics. ethics of zoos. welfare of captive species. highlighting new areas of welfare concern. highlighting new ways of captive welfare measurement.
Essay On Animals In Captivity
The zoos should make a commitment into changing visitors' perceptions about zoos and the way people are operating the zoos. Therefore, after listing some of the facts and statistics that can help people to acknowledge on animal captivity topic is not a right act because of using captivity animals as entertainment without having any freedom, confined living spaces, and the suffering of ...
Costa Rica Shuts Down State Zoos, Ends Animal Captivity
The government of Costa Rica announced this Thursday that it will close the country's two state zoos, following 11 years of litigation over a law that in 2013 prohibited keeping wild animals caged in captivity. The Ministry of Environment and Energy (Minae) indicated that "the contract with the Fundazoo Foundation, which expires this Friday ...
After Outlawing Public Zoos, Costa Rica Relocates Hundreds of Animals
By Jesus Jiménez. May 15, 2024. Costa Rica announced last week that it would close its two remaining state zoos, more than a decade after it passed a law to ban keeping wild animals in government ...
Animals
Feature papers are submitted upon individual invitation or recommendation by the scientific editors and must receive positive feedback from the reviewers. ... high seropositivity values were obtained both in animal remains in the province of Asturias [19,20] and in animals under semi-captivity during the period 2018-2022 in the province of ...
New film shows the toll Russia's invasion has taken on animals in
It's also disrupted the lives of an untold number of animals, both pets and zoo animals. An upcoming episode of Nature on PBS, "Saving the Animals of Ukraine," documents how war-torn ...

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Orcas don’t do well in captivity. Here’s why.

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History & Culture

Chronic captivity stress in wild animals is highly species-specific

L Michael Romero

Introduction

Mass and body condition in captivity

Changes in GCs during the adjustment to captivity

Impact of captivity on acute stress response and negative feedback of GC production

Immune consequences of captivity

Effects of captivity on the reproductive system

Adrenomedullary effects of captivity

Effects of captivity on seasonality of hormone regulation

Other physiological consequences of captivity

Amelioration of captivity stress

The persistence of captivity effects after release

Conclusions

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New film shows the toll Russia’s invasion has taken on animals in Ukraine

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