Show Summary Details

Page of

PRINTED FROM the OXFORD RESEARCH ENCYCLOPEDIA,  ENVIRONMENTAL SCIENCE ( (c) Oxford University Press USA, 2018. All Rights Reserved. Personal use only; commercial use is strictly prohibited (for details see Privacy Policy and Legal Notice).

date: 16 December 2018

Ethics of the Zoo

Summary and Keywords

The animal world is under increasing pressure, given the magnitude of anthropogenic environmental stress, especially from human-caused rapid climate change together with habitat conversion, fragmentation, and destruction. There is a global wave of species extinctions and decline in local species abundance. To stop or even reverse this so-called defaunation process, in situ conservation (in the wild) is no longer effective without ex situ conservation (in captivity). Consequently, zoos could play an ever-greater role in the conservation of endangered species and wildlife—hence the slogan Captivity for Conservation.

However, the integration of zoo-based tools and techniques in species conservation has led to many conflicts between wildlife conservationists and animal protectionists. Many wildlife conservationists agree with Michael Soulé, the widely acclaimed doyen of the relatively new discipline of conservation biology, that conservation and animal welfare are conceptually distinct, and that they should remain politically separate. Animal protectionists, on the other hand, draw support from existing leading accounts of animal ethics that oppose the idea of captivity for conservation, either because infringing an individual’s right to freedom for the preservation of the species is considered as morally wrong, or because the benefits of species conservation are not seen as significant enough to overcome the presumption against depriving an animal of its liberty.

Both sides view animals through different lenses and address different concerns. Whereas animal ethicists focus on individual organisms, and are concerned about the welfare and liberty of animals, wildlife conservationists perceive animals as parts of greater wholes such as species or ecosystems, and consider biodiversity and ecological integrity as key topics. This seemingly intractable controversy can be overcome by transcending both perspectives, and developing a bifocal view in which zoo animals are perceived as individuals in need of specific care and, at the same time, as members of a species in need of protection.

Based on such a bifocal approach that has lately been adopted by a growing international movement of “Compassionate Conservation,” the modern zoo can only achieve its conservation mission if it finds a morally acceptable balance between animal welfare concerns and species conservation commitments. The prospects for the zoo to achieve such a balance are promising. Over the past decade or so, zoos have made serious and sustained efforts to ensure and enhance animal welfare. At the same time, the zoo’s contribution to species conservation has also improved considerably.

Keywords: Anthropocene, captivity for conservation, One Plan Approach, animal welfare, animal ethics, environmental ethics, wildlife conservation, compassionate conservation


To develop an adequate ethical framework for the zoo, it is essential to realize that zoos are currently in the process of transition from venues of outdoor public education and entertainment to fully fledged conservation centers (The Evolution of the Zoo From Menagerie to Conservation Center).

The zoo’s contribution to species conservation is of increasing importance in the early stages of what has been called the planet’s “sixth mass extinction.” Unlike earlier mass extinctions, the current one is not primarily driven by natural events such as meteorite impacts or volcanic eruptions but by the effects of the activities of Homo sapiens. Especially human-caused rapid climate change together with habitat conversion, fragmentation, and destruction have led to a global wave of species and population extirpations and have led to declines in the abundance of local species. To halt or even reverse this so-called defaunation process, one can no longer hold on to the idea that species conservation can be accomplished with minimal management by establishing large nature reserves and by creating connections such as corridors and stepping stones between them. In situ conservation (in the wild) is no longer effective without ex situ conservation (in zoos and aquariums). In fact, the borderline between in situ and ex situ conservation is blurring as zoos are increasingly becoming more like national parks and wildlife reserves and, vice versa, parks and reserves have taken on the character of zoos (The Evolution of Ex Situ Conservation From a Subordinate to an Equivalent Role).

With the collapse of the fences between the “wild” and the “walled” and the integration of zoo-based tools and techniques in species conservation, two different ethical frameworks came into conflict: the individualistic framework of mainstream animal ethics in which species are of little or no moral relevance, and the holistic framework of environmental ethics that tends to make the rights and welfare of individual animals subordinate to the interests of the greater whole of which they are part, such as species or ecosystems. Whereas animal ethicists reject the whole idea of “captivity for conservation,” conservationists generally perceive animal welfare and animal rights concerns as obstacles to species conservation (Conservation Ethics Versus Animal Ethics).

In order to put an end to the seemingly intractable controversies between animal protectionist and wildlife managers and to integrate their conflicting ethical frameworks one will have to develop a bifocal view in which zoo animals are simultaneously perceived as individuals in need of specific care and as members of a species in need of protection. From such a bifocal view on zoo animals as individuals and species members, zoos will pursue an ethically defensible policy only if they succeed in achieving a fair balance between animal welfare concerns and species conservation commitments (A Bifocal View on Zoo Animals).

The prospects for the zoo to achieve such a balance are promising. Since the early 21st century, zoos have made serious and sustained efforts to ensure and enhance animal welfare. The zoo’s huge animal welfare concerns are reflected in the development of animal enrichment programs and the increased use of training techniques. Together, enrichment and training have transformed zoo management to the benefit of animal welfare (Zoo Animal Welfare).

At the same time, the zoo’s contribution to species conservation has also improved considerably. Zoos have found solutions for the problems created by their lack of space, such as innovative enclosure designs, specialization, regional and global cooperation, the interactive exchange of in situ and ex situ populations, and the shift away from large charismatic mammals toward smaller species. Zoos have also improved their conservation performance by broadening their conservationist role to include research, training, education, awareness campaigns, and direct financial and technical support for in situ projects (The Zoo’s Contribution to Species Conservation).

The Evolution of the Zoo From Menagerie to Conservation Center

Throughout the history from the ancient world to recent times, collections of captive wild animals have appeared primarily as menageries, usually for the greater honor and glory of the ruling classes, and as symbols of their power and prestige.1 The oldest known menagerie originated 4,300 years ago in the Sumerian city of Ur in the south of modern-day Iraq. Since then, menageries have been a feature of dynastic civilizations everywhere around the globe, from classical China to pre-Hispanic Mexico (Hancocks, 2010, p. 121).

In Europe, menageries declined after the collapse of the Roman Empire in the 5th century AD. They all but disappeared for roughly the next thousand years, with the exception of Charlemagne, who kept three menageries in the 8th century. In the Age of Discovery, the period of extensive overseas exploitation and global trade from the 15th to the 18th centuries, when navigators found many new exotic animals, royal menageries came into great favor all over Europe, and almost any royal or aristocrat owned at least one menagerie. With the exception of the Dutch, who followed the Greek tradition of collecting animals not just for show but also for study and enlightenment, menageries were maintained as manifestations of the social dominance of their owners (Hancocks, 2001, p. 16).

By the turn of the 18th century, wild animals were not only kept in stationary menageries increasingly also being exhibited in traveling menageries. These mobile animal collections were the chief attraction of country fairs and offered an opportunity to see exotic animals for large segments of the population that lacked access to the aristocratic menageries. The spectators of the traveling menagerie, the precursor of the traveling circus, transcended social divisions and boundaries of class, age, and gender (Cowie, 2013, p. 104).

The Modern Zoo

The opening in 1828 of the Zoological Garden in Regents Park, also known as the London Zoo, marked the birth of the modern zoo. It was the first zoological garden that was explicitly presented as a center of science and zoological education. It introduced the tradition of displaying its animal collection in taxonomic groupings, an approach that led to the building of the first reptile house (1849), the first public aquarium (1853), and the first insect house (1881). The huge success of the London Zoo led to a wave of zoo building across all of Europe and beyond.

It became almost essential for any self-respecting world city to have a zoological park, starting in Melbourne, Australia, in 1872, then to Philadelphia and other U.S. cities westward, and to Calcutta, Tokyo, Cairo, and Pretoria. The great swell of nineteenth-century zoo building climaxed with the opening of the Bronx Zoo in New York City, in November 1899.

(Hancocks, 2010, p. 123)

Zoos were eager to present themselves as institutions of scientific study and zoological education, and consequently to disassociate themselves from the traveling menageries and circuses of the time, which offered little more than entertainment to a curious and somewhat sensation-hungry public.

As the prospectus of the Zoological Society of London, under whose auspices London Zoo was established, proclaimed, the society aimed to acquire animals from every part of the globe “as objects of scientific research, not of vulgar admiration” (Wirtz, 1997, p. 64).

All eminent champions of the zoo were united in an effort to shift the focus of scientific research within the field of natural history from dead to living specimens of plants and animals. This effort was, however, not very successful because most zoo protagonists were autodidacts who failed to gain enough scientific credibility so as to reform traditional academics institutions. The vast majority of naturalists continued to prefer the use of dead instead of living organisms as research material. “The ‘cathedrals of science’ in the 19th century were not the zoos but the natural history museums” (Hochadel, 2005, p. 39).

So the initial mission of the founding generation had failed. On top of that, zoos came under increasing financial pressure and had to open their gates to the general public to secure their survival—hence the zoo’s new motto: “education and entertainment.” By the second half of the 19th century, zoos had changed into venues of outdoor public entertainment—“elephants and zebras were no longer scientific specimens, but mere attractions that drew carriages or gave rides to children” (Hochadel, 2005, p. 40; cf. Wirtz, 1997, p. 76).

It took until 1907 before the exemplary role of the London Zoo was seriously challenged. That year Carl Hagenbeck opened his new zoo in Hamburg, in which groups of mixed animal species were presented in full-scale naturalistic panoramas that were supposed to resemble their wild habitats. The new zoo initially displayed an African and Artic panorama. Hagenbeck’s zoo, which marked the beginning of the “naturalization” of the zoo, was to set the trend for animal exhibitry in the coming decades. The dramatic exhibits with their huge rock formations were greatly appreciated by the public, but met with disapproval from conservative zoo professionals, who feared the end of the taxonomic approach (Hancocks, 2010, p. 124).

Captivity for Conservation

During the first half of the 20th century, the zoo adhered to its mission of “education and entertainment,” today often somewhat disparagingly referred to as “edutainment.” That changed after World War II. With the inception of the World Association of Zoos and Aquariums (WAZA), zoos began to turn their attention to species conservation and wildlife protection.2 Captivity for Conservation became a crucial slogan for the modern zoo. A major milestone in this development was the Convention on Biodiversity, which was signed at the Earth Summit in Rio de Janeiro in 1992. In the wake of the Earth Summit the first World Zoo Conservation Strategy was launched in 1993. This publication, which was the result of a long-term collaboration between the WAZA and the International Union for Conservation of Nature (IUCN), explicitly stated that, at a time when species, habitats and ecosystems worldwide are threatened with extinction, modern zoos must commit to the conservation of species and wildlife.

Caring for our planet’s biological systems is one of the greatest challenges to humankind. Consequently, conservation is being seen as the central theme of zoos, and zoos should thus further evolve into conservation centers.”

(WAZA, 1993, p. 3)

In this scheme of things the zoo was envisaged as a kind of Noah’s Ark, which owed its raison d’être primarily to its contribution to the conservation of wild animal species through breeding and reintroduction programs.

The Evolution of Ex Situ Conservation From a Subordinate to an Equivalent Role

If we turn to the recent history of nature conservation, it will become clear why the zoo has assumed a prominent role in conservation. During the 1980s, it became common to distinguish two kinds of conservation, in situ and ex situ, which are Latin terms for “in place” and “out of place.” In situ conservation is the conservation of components of biological diversity in their natural habitats, whereas ex situ conservation refers to the conservation of these components outside their natural habitats, notably in seed banks, arboreta, botanical gardens, zoos, and aquariums. The distinction between in situ (on-site) and ex situ (off-site) is reminiscent of some older distinctions such as wilderness versus captivity and nature versus culture (Braverman, 2015, p. 31ff).

The Anthropocene

Up until today, in situ conservation is usually given priority over ex situ conservation. The latter is only considered justified as a supportive measure to the former. However, this hierarchical understanding of the relationship between in situ and ex situ conservation, which reflects the importance of the place of origin—“wild nature”—is increasingly being called into question given today’s ecological challenges that can be summarized under the denominator of the “Anthropocene.” This term refers to the current geological epoch in which human activities are so profound and pervasive that humanity itself has emerged as a global geophysical force, at least as important as natural forces (Crutzen & Stroemer, 2000). The beginning of this new epoch, the onset of the industrial era with its spread of fossil fuel-based energy systems in combination with its extensive use of steam engines, roughly coincides with the birth of the modern zoo.3

At the end of the Second World War, the human transformation of the global environment is supposed to have entered a new stage: the “Great Acceleration.” While the global population doubled to over six billion by the end of the 20th century, the global economy increased by nearly tenfold, with an acceleration of activities on all fronts: the damming of rivers, the use of water, the production of grain, the consumption of fertilizer and petroleum, the manufacturing of motor vehicles, etc. This burgeoning human enterprise has obviously increased the pressure on the global environment, as is evident from developments such as chemical pollution, stratospheric ozone depletion, ocean acidification, the loss of tropical rain forest, and what is considered to be the greatest mass extinction of species since the extinction of the dinosaurs 65 million years ago.4

Today, “the Great Acceleration is reaching criticality” (Steffen et al., 2007, p. 614). Anthropogenic environmental change is now taking place at such a fast speed and large scale that it definitely poses a threat to the resilience of the Earth System and could be detrimental for large parts of the human population or even for global society as a whole. Therefore a third stage is urgently needed: “Planetary Stewardship.” We will have to develop a strategy to ensure the sustainability of Earth’s life support system, or “we risk driving the Earth System onto a trajectory toward more hostile states from which we cannot easily return” (Steffen et al., 2011, p. 739).

Animal World Under Pressure

Given the scope and scale of anthropogenic stress during the current stage of the Anthropocene era, the animal world is under growing pressure. Traditional in situ (place-based) conservation measures such as the establishment of protected areas and the creation of connections between these areas seem no longer sufficient to save threatened species. Preserving the ecological status quo through such traditional measures increasingly resembles a Sisyphean task.

Under anthropocenic conditions many wild populations are no longer viable on their own. Mainly due to habitat fragmentation and habitat loss, there is an ongoing conversion of what originally were continuous populations to so-called metapopulations: collections of subpopulations, spread geographically over patches of habitat. Because these patches are usually small and the movement of the animals between these patches is restricted for lack of connectivity, an increasing number of subpopulations are declining and teetering on the brink of extinction. In this situation ex situ conservation has a more prominent role to play and is regarded as equivalent, rather than subordinate, to in situ conservation.

Because it is no longer considered effective to manage wild and captive populations in isolation from one another, practitioners of species conservation increasingly use the so-called One Plan Approach that was officially proposed to the IUCN World Conservation Congress in 2012. The One Plan Approach promotes the interactive exchange of animals between in situ populations (in the wild) and ex situ populations (in captivity) for mutual reinforcement, a management approach that is also referred to as inter situ conservation (Braverman, 2014) or pan situ conservation (Minteer & Collins, 2013). With animals moving in both directions, the stability and sustainability of wild and captive populations can be greatly enhanced. Captive populations can be used for restocking in areas with declining populations or for reintroduction in areas where populations have gone extinct. And genetic founders from wildlife populations can boost the demographic and genetic viability of ex situ populations (Byers et al., 2013).

With the One Plan Approach captive populations can be used for the conservation of in situ populations on the brink of extinction as a result of habitat fragmentation. But what if in situ conservation itself is being undermined by that other major environmental stressor—rapid global climate change—which makes the species’ historic indigenous ranges increasingly inhospitable? And when, moreover, populations are not able to move on their own to other areas with more suitable environmental conditions? A conservation measure that may prevent species that are unable to keep pace with rapid climate change from going extinct is assisted migration or assisted colonization, that is, the intentional movement of “climate refugees” to new habitats outside their historical range, which they otherwise could not reach (Hoegh-Guldberg et al., 2008). Whereas inter or pan situ conservation involves the movement of animals from one location to another within the species’ indigenous range, assisted migration or colonization refers to animal translocations outside the species’ indigenous range.5

The emergence of these new conservation strategies makes it clear that the distinction between classic in situ and ex situ conservation is becoming blurred to the point of disappearing entirely. We witness what Braverman (2015, p. 15) has called a shift “from bifurcation to amalgamation” of in situ and ex situ conservation: the increased development of hybrid approaches, which integrate the wild and the captive. (Minteer et al., 2016; Pritchard et al., 2011; Redford et al., 2012, 2013). Zoo-based expertise in sustaining small but demographically and genetically sound populations of captive animals has been proven useful for the conservation of small and declining populations in the wild. Zoo-based skills in animal handling may, moreover, be helpful at many of the main stages of animal translocations, from capture, transport, and captive breeding, to rehabilitation—that is, training animals to living in their natural habitat (again)—and release (Fa et al., 2011, p. 210).

Conservation Ethics Versus Animal Ethics

However, the integration of zoo-based techniques has led to manifold conflicts between wildlife conservationists and animal protectionists (Keulartz, 2016; Minteer & Collins, 2013). As Michael Soulé has remarked in his presidential address at the third annual meeting of the Society for Conservation Biology in 1989, “Conflicts between animal rights groups and management agencies are increasing in frequency and cost—the cost being borne by endangered species and ecosystems as well as by the public that pays for expensive rescue operations and time-consuming court battles” (Soulé, 1990, p. 235). In his seminal article “What is Conservation Biology?,” Soulé argued that “the ethical imperative to conserve species diversity is distinct from any social norms about the value or the welfare of individual animals” (Soulé, 1985, p. 731). Many wildlife conservationists agree with Soulé that conservation and animal welfare are conceptually distinct, and should remain politically separate.

Michael Hutchins, who held a leading position in the North-American Association of Zoos and Aquaria (AZA) from 1990–2005 and in The Wildlife Society (TWS) from 2005–2012, went a step further by arguing that animal rights and conservation ethics are inherently incompatible, at the most fundamental level, and “that one cannot be an animal rights proponent and a conservationist simultaneously” (Hutchins, 2008, p. 816). As Hutchins rightly points out, animal rights proponents have fought vehemently against virtually every form of wildlife research or management.6

Most animal rights proponents consider infringing an individual’s right to freedom for the sake of the preservation of the species as morally wrong. According to Tom Regan, who developed an animal rights approach along deontological lines in his 1983 book The Case for Animal Rights, animals, notably mammals, should not simply be appreciated for their instrumental value but should be respected for their intrinsic value. To achieve this, we should grant animals certain rights. For Regan any type of captivity or manipulation of a sentient animal is morally unacceptable, irrespective of the possibly beneficial consequences for the protection of rare or endangered species. The rights view’s answer to the question whether zoos are morally defensible, “not surprisingly, is No, they are not” (Regan, 1995, p. 46).

Peter Singer’s animal welfare approach is less restrictive than Regan’s animal rights position on the moral acceptability of zoos. In his 1975 book Animal Liberation, Singer developed an animal ethic along utilitarian lines, in which he extended the utilitarian moral maxim of “the greatest good for the greatest number” to include all sentient beings with a capacity for suffering. Singer seems to accept some reductions in animal welfare when the survival of entire populations or species is at stake. However, most zoos, according to Singer, fail to live up to their conservation mission, and tend to confine animals for our amusement in ways that are contrary to their interests. Dale Jamieson, another animal ethicist working in the utilitarian tradition, is even more skeptical about zoos than Singer; he considers the benefit of species conservation “not significant enough to overcome the presumption against depriving an animal of its liberty” (Jamieson, 1995, p. 60).

Both Singer’s utilitarian (animal welfare) approach and Regan’s deontological (animal rights) approach center on individual organisms. Animal ethicists of all colors agree with Singer and Regan that only individual animals have intrinsic value and direct moral standing, not collective entities such as species or ecosystems.7 While Singer believes that we have no duties to species because as such they “are not conscious entities and so do not have interests above and beyond the interests of the individual animals that are members of the species” (Singer, 1979, p. 203), Regan holds that the rights view does not recognize the moral rights of species to anything, including survival.

That an individual animal is among the last remaining members of a species confers no further right on that animal. If we had to choose between saving the last two members of an endangered species or saving another individual who belonged to a species that was plentiful but whose death would be a greater prima facie harm to that individual than the harm that death would be to the two, then the rights view requires that we save that individual.

(Regan, 1983, p. 359ff.)

Individualism Versus Holism

It is hardly a surprise that conservationists will not be able to achieve most of their targets under current anthropocenic conditions within such an individualistic framework. They turn for support to environmental philosophers who advocate a holistic perspective in which animals are perceived as parts of a greater whole such as species or ecosystems. The locus classicus of this holistic approach is A Sand County Almanac, published in 1949 by famous nature conservationist Aldo Leopold. The basic moral rule of his so-called land ethic goes as follows: “A thing is right when it tends to preserve the integrity, stability, and beauty of the biotic community. It is wrong when it tends otherwise.”

Around 1980, a fierce conflict erupted between individualistic animal ethicists and holistic environmental ethicists (Hargrove, 1992). Before that time it was expected that an adequate environmental ethics would develop as a natural extension of animal ethics. Both Peter Singer’s animal liberation theory and Tom Regan’s animal rights theory denounced traditional morality for its “human chauvinism” and its “speciesism.” The time seemed ripe for a moral rehabilitation of the rest of animate nature, and animal ethicists and environmental ethicists were supposed to join forces in fighting for wildlife preservation. But, as Mark Sagoff (1984) has remarked somewhat sarcastically, this was a “bad marriage,” followed by a “quick divorce.”

In 1980, Baird Callicott published a highly polemical article to counter the widespread view that the existing animal ethics of Singer and Regan were fully capable of answering all environmental ethical questions. According to Callicott, animal ethicists demonstrate their “ecological illiteracy” by according equal moral worth to each and every member of the biotic community irrespective of whether they are tame or wild, rare or common, indigenous or exotic; “the moral worth of individuals is relative, to be assessed in accordance with the particular relation of each to the collective entity which Leopold called ‘land’” (Callicott, 1980, p. 327). Tom Regan responded to these attacks against the animal ethicists’ basic principle with the accusation that environmental ethicists were committing the crime of “environmental fascism” by subordinating the rights of individuals to the interests of the greater whole. “Environmental fascism and the rights view are like oil and water, they don’t mix” (Regan, 1983, p. 362).

Animal ethicists and environmental ethicists usually not only differ with regard to the locus of moral concern—individual organisms or greater wholes—they also tend to use different species concepts (Sandler, 2012, p. 4). Animal ethicists have generally adopted a conventionalist species concept; they see a species merely as a category or class with arbitrarily drawn boundary lines that may serve as a convenient mapping device for theoretical purposes only.8 Environmental ethicists, on the other hand, generally hold a realistic species concept. Holmes Rolston, for instance, argues that a species is a real historical entity, a “dynamic historical lineage” that can persist as a discrete, vital pattern over time (Rolston, 1988, p. 151).

A Bifocal View on Zoo Animals

With the breaking down of the in situ and ex situ distinction, conservation strategies increasingly have gained direct animal health and welfare impacts, which lead to serious conflicts between individualistic animal-centered and holistic species-centered ethicists and activists, to the detriment of effective conservation management. As the problems of wildlife conservation and animal welfare tend to merge under anthropocenic conditions, it is becoming abundantly clear that both groups view animals through different lenses and address different concerns (Fraser, 2010). Their views seem to be incompatible, “because what is good for conservation is not always in the best interest of individual animals and vice versa” (Paquet & Darimont, 2010, p. 184). However, over the past decade, serious efforts have been made to bridge the gap between these divergent views, most notably from an environmental pragmatism position (Light & Katz, 1996), as exemplified in the work of Benjamin Minteer (2004, 2012).

Pragmatist Anti-Dualism

One major obstacle to productive problem solving and satisfactory conflict resolution is dualistic thinking. Dualistic thinking is deeply rooted in Western philosophy, judging by the importance of the law or principle of the excluded middle that was already formulated by Aristotle. This principle asserts that every judgment is either true or false (not true); there is no third possibility: tertium non datur! This “law of the excluded third” has a paralyzing effect on many scientific and societal debates. It is in line with a whole host of dichotomies that characterize Western thought, such as theory and practice, fact and value, body and mind, and reason and emotion. In the debate between animal rights and conservation we also encounter a number of dichotomies, such as wild and captive animals; instrumental and intrinsic value; and, of course, moral individualism and moral holism. These dichotomies encourage black-and-white thinking that does not allow for shades of gray or for a middle course but brings conflicts to a head and leads debates to degenerate into unproductive boundary disputes.

Such seemingly intractable controversies as those between individualistic animal rights proponents and holistic conservation managers require what Donald Schön and Martin Rein, inspired by John Dewey’s idea of “reconstructive thinking,” have called “frame restructuring,” that is, the attempt to integrate conflicting frames. As a necessary first step toward such an integration, both sides of the controversy have to develop a “double vision,” namely “the ability to act from a frame while cultivating awareness of alternative frames” (Schön & Rein, 1994, p. 207). They should learn to “squint” so to speak in order to see things from both angles simultaneously.

Common Ground

An important way to integrate conflicting frames is by looking for common ground, that is, by shifting the focus from disagreements to background agreements and deeper shared values. Potentially at least, there seems to be enough common ground and converging interests between animal rights proponents and wildlife managers to allow for fruitful cooperation. Once they recognize that they share an interest in animal welfare, be it on different scales, they might be able to settle some of their conflicts and find creative solutions to practical problems (Perry & Perry, 2008). It could even be argued that animal welfare and wildlife conservation are two sides of the same coin, “by showing that the integrity of habitats and the populations they contain are inextricably linked to the welfare of the individual animals that constitute those populations and occupy those habitats” (Paquet & Darimont, 2010, p. 179). If animal welfare concerns are ignored, wildlife conservation policies are likely to fail, and vice versa (Fraser, 2010, p. 123).

A movement that wants to venture beyond the “tyranny of small differences” between the fields of animal welfare and conservation is “compassionate conservation” (Bekoff, 2013). It has increasingly gained traction after an international symposium at the University of Oxford in September 2010. Compassionate conservation represents a new paradigm that intends to draw both fields closer together. By incorporating the protection of animals as individuals and not just as members of species, the movement represents a decisive break with the tradition in which animal welfare was generally been thought of as an impediment to conservation (Ramp & Bekoff, 2015).

It seems obvious that from such a bifocal view on animals as individuals and as species members, zoos will be morally justifiable only if the costs in terms of animal welfare and freedom are clearly outweighed by the benefits to species preservation (Keulartz, 2015). In the remainder of this article I will examine whether and how the zoo succeeds in achieving an ethically defensible balance between animal welfare concerns and species conservation commitments. I will first look at the zoo’s efforts to ensure animal welfare and then discuss its track record regarding conservation outcomes.

Zoo Animal Welfare

Even though there has been an increasing tendency toward the “naturalization” of the zoo since the opening of Carl Hagenbeck’s zoo in 1907, this process has also reached its limits. Zoos cannot include the reproduction of natural contingencies. Some forms of predatory behavior, such as chasing and killing prey, cannot realistically be simulated in captivity. Likewise, in the absence of predators, some forms of prey behavior, such as vigilance, may not be exhibited at appropriate levels in captivity. In short, captivity usually deprives wild animals of the necessity and opportunity to pursue the tasks of survival, such as finding food and avoiding enemies.

Heini Hediger, the Swiss pioneer of zoo biology, considered this lack of occupation of the captive animal as “one of the most urgent problems in the biology of zoological gardens” (Hediger, 1950, p. 158). Quite a lot of studies show that animals prefer to work for their food, rather than to be fed ad libitum; they will most often voluntarily work for their food, even if the same food is available free (Anderson & Chamove, 1984; Laule & Desmond, 1998). Especially mammals are unsuited to an existence in which no effort on their part is required to meet their basic needs (Kreger et al., 1998).

A solution to this problem is “substitution.” Animals, particularly mammals, are flexible enough to modify their behavior to suit a wide range of situations and to substitute one form of action for another depending on the facilities available. In Frontiers of Justice, Martha Nussbaum mentions an example of substitution. Modern zoos have to face the problem of allowing the capabilities of predatory animals like tigers to be exercised without actually harming or killing prey animals. The Bronx Zoo has found an answer to this question—instead of giving a tiger a tender gazelle to crunch on, it gives the tiger a large ball on a rope, whose resistance and weight symbolize the gazelle. “Wherever predatory animals are living under direct support and control,” Nussbaum concludes, “these solutions seem the most ethically sound” (Nussbaum, 2006, p. 370).

Environmental Enrichment

The introduction of such novel objects—“toys and treats”—is just one option for providing “environmental enrichment,” by which the expression and development of species-specific behaviors and abilities can be achieved, usually to the benefit of animal welfare. Feeding enrichment is also an important option. Anna Claxton (2011) mentions three strategies in feeding enrichment: increasing the number of daily feeding sessions; making the feeding schedule less predictable; and making the food less easy to obtain, either by hiding it or by adding a level of complexity to the food manipulation process, such as providing live prey or full carcass meals.

Another major enrichment strategy concerns the improvement of enclosure design. Most zoos suffer from a severe lack of space (see the next section). A recent and also very promising strategy to tackle this problem, concerns the creation of walkways between enclosures that allow animals greater freedom of movement. Building a network of trails, in particular top tree trails, gives animals the opportunity to rotate between various interconnected display and off-display areas. Animals may spend mornings in one area and afternoons in another. The concept of such animal rotation displays is based on Hediger’s theory of territory, a wild animal’s living space made up of a variety of special areas, such as dens, basking sites, and foraging areas, interconnected by regular pathways (Coe, 2004).

Still other methods of environmental enrichment for captive animals include sensory stimulation in the form of auditory, olfactory and visual cues, and social enrichment, which provides animals the opportunity to interact with other animals, either conspecifics (same species) or contraspecifics (other species). Mixed-species exhibits are a good example of the latter. They provide an interactive and dynamic experience for the animals, visitors, and zoo staff. In mixed-species enclosures activity levels are typically higher, with more play behaviors, and this generally has a positive effect on both the physical and the mental health of the animals (Veasey & Hammer, 2010, p. 151). Moreover, interspecific interactions can contribute to successful reintroductions. Animals from mixed-species exhibits are more likely to cope with the complexity of their natural habitat after introduction. Even “negative” interspecific interactions, for example, controlled nonlethal exposure to predators, may be beneficial in survival postrelease (Veasey & Hammer, 2010, p. 153).


Finally, a special case of environmental enrichment concerns what Hediger has called “occupational therapy.” “The captive animal,” Hediger suggested, “must be given a new interest in life, an adequate substitute for the chief occupation of freedom . . . This substitute can take the form of biologically suitable training and assumes the importance of occupational therapy” (Hediger, 1950, p. 158).

Animal training is an important component of animal enrichment programs as it facilitates exercise and mental stimulation. Training can also provide the animals with the motivation, skill, and confidence they need to use the enrichment devices they have been offered in the most successful way. Through training by positive reinforcement, animals can be taught to participate in daily health and husbandry care, without sedation or restraint. By voluntarily participating in their treatment during dental work, blood draws, urine collection, stethoscope examinations, artificial inseminations, etc., they will obtain benefits in the form of preventive and curative health care. Also, the stress that is usually related to these procedures can be significantly reduced by teaching animals to voluntarily participate in their daily health and husbandry care.

Training is also relevant for the relationship between the animal and its care giver, which is of critical importance for many species in captivity. The well-being of zoo animals is greatly enhanced if there is a trusting, amiable relationship with their keepers. The trust between animals and keepers can be reinforced by training animals to follow commands, and teaching them simple routines using positive reinforcement. “Building a trusting and caring relationship, teaching the different procedures on cue and establishing strong reinforcement histories with our animals, enabling them to behave in a secure manner and provide the ability to anticipate what is happening to them, whether good or bad” (Brando, 2010, p. 783).

We can safely conclude, that with the recent focus on animal enrichment and the extraordinary increase in the use of training techniques, zoo management has undergone a real transformation to the benefit of animal welfare (Kleiman, 2010, p. xi).

The Zoo’s Contribution to Species Conservation

As already indicated, after WW II the zoo was increasingly envisioned and legitimized as a kind of Noah’s Ark. But initially the zoo had trouble to realize this ambition. The Ark was hitting rough water as the conservation breeding programs already quite soon ran into some substantial problems. Many of the animals exhibited in zoos do not belong to groups designated for conservation. Because the space for all the zoo animals in the world could easily fit within New York’s 212.7 km2 borough of Brooklyn (Conway, 2011, p. 4), zoos can only maintain a limited number of endangered species. Even if zoos were to dedicate half their space to conservation breeding programs, they would still—according to the most optimistic estimates—be unable to accommodate more than around 800 of the 7,368 species of vertebrates that are threatened with extinction according to the 2013 IUCN Red List.9

Research has shown that zoos currently hold roughly 1 in 7 (15%) threatened species of terrestrial vertebrates (Conde et al., 2011). However, the network of more than 800 zoos and aquariums in 80 countries worldwide, which are part of the International Species Information System (ISIS), already devotes 23% of its collections to threatened species. Conservation breeding programs have played a major role in the recovery of 13 of the 68 IUCN Red List species whose threat level was reduced, including Przewalski’s wild horse, black-footed ferret, and California condor. Since ensuring protected areas alone is no longer sufficient to save threatened species, conservation breeding programs together with reintroduction programs and hunting restrictions have been the most effective conservation actions for mammals (Conde et al., 2013).

Nonetheless, it is evident that zoos, because of space limits, can currently only maintain a small fraction of threatened species. To make matters worse, zoos even struggle to properly breed these few species because the populations are usually too small. Initially, the target of zoo breeding programs was to maintain 90% of genetic variability of a species for a period of 200 years (Soulé et al., 1986). Because this time frame requires very large numbers of animals per species, it has been reduced from 200 to 100 years in the mid-1990s. But the majority of breeding programs do not have sufficient space to meet even this objective.

Furthermore, to the extent that conservation breeding programs are successful, the animal populations will almost certainly exceed the zoo’s carrying capacity. This situation creates the so-called surplus animal problem. Traditional methods to solve this problem include culling the surplus animals or selling them to dealers, where they often end up in substandard facilities (Carter & Kagan, 2010). Such disposition methods are among the most sensitive public relations issues zoos face, and tend to severely undermine their conservation message. This became abundantly clear in a case that sparked worldwide outrage, namely, the case of Marius, a healthy young male giraffe at the Copenhagen Zoo, who was put to death on February 9, 2014, publicly dissected, his remains being fed to the zoo’s carnivores.

Not only are the success rates of conservation breeding programs disappointing, also the prospects of reintroduction programs are low, largely because ecological, social, economic, and political aspects were not taken into consideration. Reintroduction is a costly business, which often diverts attention from other, more cost-effective options. In captivity, animals risk losing the skills they need to survive in the wild. Lastly, the ecosystems into which they are eventually released are dynamic systems, which have often undergone dramatic changes in the time span between the breeding program and the reintroduction, sometimes as a result of anthropogenic disturbances such as climate change and deforestation. Although the situation improved after the development of the Guidelines for the Placement of Confiscated Animals (IUCN, 2000), the performance of zoos regarding the reintroduction of captive-bred animals still fell far short of expectations.

By the turn of the century, Noah’s Ark seemed to have become irretrievably shipwrecked. Zoo professionals and managers needed all hands on deck to keep the Ark afloat. They had to make some important improvements, especially regarding the urgent problems caused by limits of space. One type of improvements concerns the creation of more space for endangered species, and the other involves the development of a much broader conservationist role for zoos than captive breeding for (re)introduction.

Creating More Space

To address the problem of space limits, zoos have a number of options. They can create more space by improving their enclosure design (see Zoo Animal Welfare). They can reduce the number of species they maintain that are not threatened and specialize in species that are. “Specialization is key to every successful threatened species propagation program” (Conway, 2011, p. 5). In addition to specialization zoos can increase and improve regional and global cooperation. Only very few captive populations managed in isolation are self-sustaining since population sizes generally need to be very large to retain 90% of the genetic diversity over 100 years. The problem of low numbers can be addressed by collaborative management and the exchange of animals among zoos.

Initiatives to develop and support cooperative management of captive animal populations have been underway for some time already. In the early 1980s the North-American Association of Zoos and Aquariums (AZA) launched so-called Species Survival Plans (SSPs), which facilitate captive breeding between accredited zoos across the region. In 2015, the AZA managed 478 of such animal programs. Cooperative zoo animal programs were also developed by other regional associations such as the European Association of Zoos and Aquariums (EAZA) and Australasia’s Zoo and Aquarium Association (ZAA). In addition, the WAZA adopted a procedure for establishing interregional programs at its 2003 annual conference. It has taken some time for these so-called Global Species Management Plans (GSMPs) to gain momentum within the world zoo and aquarium community, but in 2013 WAZA managed no less than 11 taxa through such GSMPs (Braverman, 2015, p. 68).

Another way to combat the problem of numbers, besides the regional and interregional exchange of animals between zoos, is the interactive exchange between in situ populations (in the wild) and ex situ populations (in captivity). The integration of in situ and ex situ programs through the One Plan Approach (see The Evolution of Ex Situ Conservation from a Subordinate to an Equivalent Role) opens the possibility to simultaneously improve the demographic stability and genetic diversity of the wild and captive populations of endangered species.

But the most effective strategy to combat the problem of limited space is without any doubt a shift away from the large charismatic mammals toward smaller species, particularly amphibians, invertebrates, and some species of fish, which occupy less space, are relatively inexpensive to keep, generally experience less welfare problems in captivity, have a high birth rate, and are easy to reintroduce. Several initiatives have already been launched on this front, not least the Amphibian Conservation Action Plan, a partnership involving the WAZA (Gewin, 2008).

Some fear that turning the spotlight on small species will weaken the attraction of zoos. Zoos need to balance conservation credibility with commercial viability; to reach the aim of species conservation they need to attract visitors. However, the assumption that zoos will not attract enough visitors without large mega-vertebrates is far from uncontroversial. Recent findings even suggest that small mammal displays yield a higher cost to benefit ratio, in terms of exhibit popularity per unit cost, than large mammal displays. They also suggest that imaginative displays of small-bodied species can substantially increase zoo attendance (Fa et al., 2011, p. 79).

Broadening the Zoo’s Conservationist Role

The new World Zoo and Aquarium Conservation Strategy of 2005 outlines a much broader conservationist role for zoos than the first World Zoo Conservation Strategy of 1993, including research, training, education, awareness campaigns, and direct support for in situ projects. In the latest strategy, the primary mission of zoos is to integrate all these elements with their efforts to protect endangered species and conserve healthy ecosystems (Bowkett, 2008; Lees & Wilcken, 2009; Mace et al., 2007). Insofar as captive breeding for reintroduction is considered necessary and appropriate, it should be accomplished as part of such a larger, integrated, holistic program (Hutchins, 2003, p. 18).

The simplest way for zoos to assist in situ conservation is through financing and fundraising. The amount spent on conservation by zoos is significant. Members of the WAZA are the third largest financial supporter of species conservation in their natural habitats (providing $350 million/year), after the Nature Conservancy and the World Wildlife Fund (Conde et al., 2011). But investment in conservation by zoos is generally still somewhat low. Available data point to less than 5% of income being spent on in situ conservation (Fa et al., 2011), while it has been suggested that zoos devote at least 10% of their income to this cause (Tribe & Booth, 2003).

Another important way for zoos to contribute to in situ conservation is through research and training. Exporting expertise is at least as important as repatriating animals (Stanley Price & Fa, 2007, p. 169). As natural habitats continue to being damaged and destroyed at the current pace, the tools and technologies developed by zoos are becoming increasingly relevant for in situ conservation. Research within zoos, such as behavior studies, genetics, reproduction, and nutrition are increasingly relevant for research in the wild. Moreover, zoos can support in situ conservation by providing technical skills and by training conservation scientists (Zimmerman, 2010, p. 282).

But perhaps the most important contribution of zoos to in situ conservation comes from education, awareness, and advocacy. It is realized by now that the 700 million people that annually visit zoos are significant conservation assets, at least as valuable as the zoos’ animals.10 Only recently have zoo professionals begun to objectively assess their educational impact on visitor conservation knowledge, awareness, and behavior, in order to learn and improve their competence as agents of change. It took some time for zoo visitor research to reach maturity. One early major zoo visitor study, which involved more than 5,500 visitors and 12 AZA-accredited institutions—and that found, for the first time, direct evidence that zoos have a positive impact in changing visitors’ feelings and attitudes about conservation (Falk et al., 2007)—was heavily criticized for containing “at least six major threats to methodological validity that undermine the author’s conclusions” (Marino et al., 2010, p. 126).

There are, however, already some methodological robust studies that show the potential educational value of visiting zoos. One of these studies was conducted by Eric Jensen (2014). His research focused on the educational impact of zoo visits on children and adolescents, a group that has been neglected in zoo visitor research, despite the fact that millions of children visit zoos every year with their school. Jensen’s large-scale (n = 2839) study, which lacks the methodological flaws associated with prior research on educational impacts, broadly supports the idea that zoo visits can deliver pro-conservation learning and attitudinal impacts.

To enhance the effectiveness of zoo visits to inspire conservation awareness and action, zoo professionals have shifted the focus from cognitive learning to affective learning. In addition, they have recognized that behavioral change on a measurable scale is only feasible if zoos succeed in encouraging accessible actions that people can take to support wildlife (Routman et al., 2010, p. 140). A good case in point is Monterey Bay Aquarium that hands out the Seafood Watch Pocket Guide to its visitors. As it turned out, this guide significantly changes the seafood-buying habits of 80% of visitors who take one home (Routman et al., 2010, pp. 141–145). Another good example is the They’re Calling on You campaign at Melbourne Zoo. Visitors to the gorilla enclosure are asked to donate their old mobile phones, which are then sent off for recycling. The idea is to save coltan, an ore that is mined at the expense of the gorillas’ habitat, and to generate funding for their conservation.

With the creation of more space for threatened and endangered species and the broadening of their conservationist role, a growing number of zoos are in the process of transition from a zoo that contributes to conservation to a conservation organization that runs a zoo (Zimmerman, 2010, p. 285). Although many zoos still have a way to go, the direction is clear.

Concluding Remarks

As the current stage of the Anthropocene—the “Great Acceleration”—is reaching criticality, the borderline between in situ and ex situ conservation becomes more and more blurred, and the use of zoo-based tools and techniques more and more common practice in wildlife management. Under these circumstances, there is an urgent need to develop a bifocal view that allows for seeking and exploring common ground between animal protectionists (with an individualistic framework) and wildlife conservationists (with a holistic framework), to transcend their differences and move beyond the black-and-white thinking that has led their debates time and again to a total deadlock. On the basis of present trends—the development of animal enrichment and training programs on the one hand and the improvement of the contribution to in situ conservation on the other—one can conclude with some confidence that the prospects for zoos to achieve an ethically acceptable balance between animal welfare concerns and species conservation commitments look promising.


Anderson, J., & Chamove, A. (1984). Allowing captive primates to forage. In Standards in laboratory animal management (Vol. 2, pp. 253–257). Potters Bar, U.K.: Universities Federation for Animal Welfare.Find this resource:

Bekoff, M. (Ed.). (2013). Ignoring nature no more. The case for compassionate conservation. Chicago: University of Chicago Press.Find this resource:

Bowkett, A. E. (2008). Recent captive-breeding proposals and the return of the Ark concept to global species conservation. Conservation Biology, 23(3), 773–776.Find this resource:

Brando, S. (2010). Advances in husbandry training in marine mammal care programs. International Journal of Comparative Psychology, 23, 777–791.Find this resource:

Braverman, I. (2014). Captive for life: Conserving extinct in the wild species through ex situ breeding. In L. Gruen (Ed.), The ethics of captivity (pp. 193–212). Oxford: Oxford University Press.Find this resource:

Braverman, I. (2015). Wild life. The institution of nature. Stanford, CA: Stanford University Press.Find this resource:

Byers, O., Lees, C., Wilcken, J., & Schwitzer, C. (2013). The One Plan approach: The philosophy and implementation of CBSG’s approach to integrated species conservation planning. WAZA Magazine, 14, 2–5.Find this resource:

Callicott, J. B. (1980). Animal liberation: A triangular affair. Environmental Ethics, 2, 311–338.Find this resource:

Carter, S., & Kagan, R. (2010). Management of “surplus” animals. In D. Kleiman, K. Thompson, & C. Kirk Baer (Eds.), Wild mammals in captivity (pp. 263–267). Chicago: University of Chicago Press.Find this resource:

Claxton, A. (2011). The potential of the human–animal relationship as an environmental enrichment for the welfare of zoo-housed animals. Applied Animal Behaviour Science, 133, 1–10.Find this resource:

Coe, J. (2004). Mixed species rotation exhibits. Jon Coe Design Pty Ltd. (originally prepared for ARAZPA 2004 Annual Conference).Find this resource:

Conde, D., Colchero, F., Gusset, M., Pearce-Kelly, P., Byers, O., Flesness, N., et al. (2013). Zoos through the lens of the IUCN Red List: A global meta-population approach to support conservation breeding programs. PLoS One, 8(12), 1–9.Find this resource:

Conde, D., Flesness, N., Colchero, F., Jones, O., & Scheuerlein, A. (2011). An emerging role of zoos to conserve biodiversity. Science, 331(6023), 1390–1391.Find this resource:

Conway, W. (2011). Buying time for wild animals with zoos. Zoo biology, 30, 1–8.Find this resource:

Corlett, R. T. (2015). The Anthropocene concept in ecology and conservation. Trends in Ecology & Evolution, 30(1), 36–41.Find this resource:

Cowie, H. (2013). Elephants, education and entertainment. Travelling menageries in nineteenth-century Britain. Journal of the History of Collections, 25(1), 103–117.Find this resource:

Crutzen, P., & Stroemer, E. (2000). The “Anthropocene.” IGBP Newsletter, 41, 17–18.Find this resource:

Gewin, V. (2008). Riders of a modern-day Ark. PLoS Biology, 6(1), 18–21.Find this resource:

Fa, J., Funk, S., & O’Connell, D. (2011). Zoo conservation biology. Cambridge, U.K.: Cambridge University Press.Find this resource:

Falk, J. H., Reinhard, E. M., Vernon, C. L., Bronnenkant, K., Heimlich, J. E., & Deans, N. L. (2007). Why zoos & aquariums matter: Assessing the impact of a visit to a zoo or aquarium. Silver Spring, MD: Association of Zoos & Aquariums.Find this resource:

Fraser, D. (2010). Toward a synthesis of conservation and animal welfare science. Animal Welfare, 19, 121–124.Find this resource:

Hancocks, D. (2001). A different nature. The paradoxical world of zoos and their uncertain future. Berkeley: University of California Press.Find this resource:

Hancocks, D. (2010). The history and principles of zoo exhibition. In D. Kleiman, K. Thompson, & C. Kirk Baer (Eds.), Wild mammals in captivity (pp. 121–136). Chicago: University of Chicago Press.Find this resource:

Hargrove, E. (Ed.). (1992). The animal rights/environmental ethics debate. The environmental perspective. Albany: State University of New York Press.Find this resource:

Hediger, H. (1950). Wild animals in captivity. London: Butterworths.Find this resource:

Hochadel, O. (2005). Science in the 19th-century zoo. Endeavour, 29(1), 38–42.Find this resource:

Hoegh-Guldberg, O., Hughes, L., McIntyre, S., Lindenmayer, Parmesan, C., Possingham, H.P., et al. (2008). Assisted colonization and rapid climate change. Science, 321(5887), 345–346.Find this resource:

Hutchins, M. (2003). Zoo and aquarium animal management and conservation: Current trends and future challenges. International Zoo Yearbook, 38, 14–28.Find this resource:

Hutchins, M. (2007). The animal rights-conservation debate: Can zoos and aquariums play a role? In A. Zimmermann, M. Hatchwell, L. Dickie, & C. West (Eds.), Zoos in the 21st century. Catalysts for conservation (pp. 92–109). Cambridge, U.K.: Cambridge University Press.Find this resource:

Hutchins, M. (2008). Animal rights and conservation. Conservation Biology, 22(4), 815–816.Find this resource:

Hutchins, M., & Wemmer, C. (1986). Wildlife conservation and animal rights: Are they compatible?” In M. W. Fox & L. D. Mickley (Eds.), Advances in animal welfare science 1986/87 (pp. 111–137). Washington, DC: Humane Society of the United States.Find this resource:

IUCN (2000). Guidelines for the placement of confiscated animals. Gland, Switzerland: IUCN.Find this resource:

IUCN/SSC (2013). Guidelines for reintroductions and other conservation translocations. Version 1.0. Gland, Switzerland: IUCN Species Survival Commission.Find this resource:

Jamieson, D. (1995). Zoos revisited. In B. Norton, M. Hutchins, E. Stevens, & T. Maple (Eds.), Ethics on the Ark (pp. 52–66). Washington, DC: Smithsonian Institution Press.Find this resource:

Jensen, E. (2014). Evaluating children’s conservation biology learning at the zoo. Conservation Biology, 28(4), 1004–1011.Find this resource:

Keulartz, J. (2015). Captivity for conservation? Zoos at a crossroads. Journal of Agricultural and Environmental Ethics, 28, 335–351.Find this resource:

Keulartz, J. (2016). Towards an animal ethics for the Anthropocene. In B. Bovenkerk & J. Keulartz (Eds.), Animal ethics in the age of humans (pp. 243–264). Dordrecht, The Netherlands: Springer.Find this resource:

Kleiman D. (2010). Preface. In D. Kleiman, K. Thompson, & C. Kirk Baer (Eds.), Wild mammals in captivity. Principles and techniques for zoo management (2d ed., pp. xi–xii). Chicago: University of Chicago Press.Find this resource:

Kreger, M., Hutchins, M., & Fascione, N. (1998). Context, ethics, and environmental enrichment in zoos and aquariums. In D. Shepherdson, J. Mellen, & M. Hutchins (Eds.), Second nature. Environmental enrichment for captive animals (pp. 59–82). Washington, DC: Smithsonian Institution Press.Find this resource:

Laule, G., & Desmond, T. (1998). Positive reinforcement training as an enrichment strategy. In D. Shepherdson, J. Mellen, & M. Hutchins (Eds.), Second nature. Environmental enrichment for captive animals (pp. 302–313). Washington, DC: Smithsonian Institution Press.Find this resource:

Lees, C. M., & Wilcken, J. (2009). Sustaining the Ark: The challenges faced by zoos in maintaining viable population. Zoo Yearbook, 43, 6–18.Find this resource:

Light, A., & Katz, E. (Eds.) (1996). Environmental pragmatism. London: Routledge.Find this resource:

Mace, G. M., Balmford, A., Leader-Williams, N., Manica, A., Walter, O., West, C., & Zimmermann, A. (2007). Measuring conservation success: Assessing zoos’ contribution. In A. Zimmermann, M. Hatchwell, L. Dickie, & C. West (Eds.), Zoos in the 21st century. Catalysts for conservation (pp. 322–342). Cambridge, U.K.: Cambridge University Press.Find this resource:

Marino, L., Lilienfeld, S. O., Malamud, R., Nobis, N., & Brogliod, R. (2010). Do zoo and aquariums promote attitude change in visitors? A critical evaluation of the American zoo and aquarium study. Society and Animals, 18, 126–138.Find this resource:

Minteer, B. (2004). Beyond considerability: A Deweyan view of the animal rights-environmental ethics debate. In E. McKenna & A. Light (Eds.), Animal pragmatism, rethinking human-nonhuman relationships (pp. 97–118). Bloomington: Indiana University Press.Find this resource:

Minteer, B. (2012). Refounding environmental ethics. Pragmatism, principle, and practice. Philadelphia: Temple University Press.Find this resource:

Minteer, B., & Collins, J. (2013). Ecological ethics in captivity: Balancing values and responsibilities in zoo and aquarium research under rapid global change. ILAR, 54(1), 41–51.Find this resource:

Minteer, B., Collins, J., & Raschke, A. (2016). Between the wild and the walled: The evolution and ethics of zoo conservation. In: B Hale & A. Light (Eds.), Routledge companion to environmental ethics. New York: Routledge.Find this resource:

Nussbaum, M. C. (2006). Frontiers of justice. Disability, nationality, species membership. Cambridge, MA: Harvard University Press.Find this resource:

Paquet, P.C., & Darimont, C.T. (2010). Wildlife conservation and animal welfare: two sides of the same coin? Animal Welfare, 19(2), 177–190.Find this resource:

Perry, D., & Perry, G. (2008). Improving interactions between animal rights groups and conservation biologists. Conservation Biology, 22(1), 27–35.Find this resource:

Pritchard, D., Fa, J., Oldfield, S., & Harrop, S. (2011). Bring captive closer to the wild: Redefining the role of ex situ conservation. Oryx, 46(1), 18–23.Find this resource:

Ramp, D., & Bekoff, M. (2015). Compassion as a practical and evolved ethic for conservation. BioScience, 65(3), 323–327.Find this resource:

Redford, K., Jensen, D., & Breheny, J. (2012). Integrating the captive and the wild. Science, 338, 1157–1158.Find this resource:

Redford, K., Jensen, D., & Breheny, J. (2013). The long overdue death of the ex situ and in situ dichotomy in species conservation. WAZA Magazine, 14, 19–22.Find this resource:

Regan, T. (1983). The case for animal rights. Berkeley: University of California Press.Find this resource:

Regan, T. (1995). Are zoos morally defensible? In B. Norton, M. Hutchins, E. Stevens, & T. Maple (Eds.), Ethics on the Ark (pp. 38–51). Washington, DC: Smithsonian Institute Press.Find this resource:

Reid, G. M. (2016). Changed attitudes to nature reflected in the transformation of menageries to zoos. In I. Convery & P. Davis (Eds.), Changing perceptions of nature (pp. 123–132). Woodbridge, U.K.: Boydell.Find this resource:

Rolston, H. (1988). Environmental ethics. Duties to and values in the natural world. Philadelphia: Temple University Press.Find this resource:

Routman, E., Ogden, J., & Winsten, K. (2010). Visitors, conservation learning, and the design of zoo and aquarium experiences. In D. Kleiman, K. Thompson, & C. Kirk Baer (Eds.), Wild animals in captivity. Principles and techniques for zoo management (2d ed., pp. 137–150). Chicago: University of Chicago Press.Find this resource:

Sagoff, M. (1984). Animal liberation and environmental ethics: Bad marriage, quick divorce. Osgoode Hall Law Journal, 22, 297–307.Find this resource:

Sandler, R. L. (2012). The ethics of species. An introduction. Cambridge, U.K.: Cambridge University Press.Find this resource:

Schama, S. (1995). Landscape and memory. London: HarperCollins.Find this resource:

Schön, D., & Rein, M. (1994). Frame reflection. New York: Basic Books.Find this resource:

Singer, P. (1975). Animal liberation: A new ethics for our treatment of animals. New York: Random House.Find this resource:

Singer, P. (1979). Not for humans only: The place of nonhumans in environmental issues. In K.E. Goodpaster & K.M. Sayre (Eds.), Ethics and problems of the 21st century (pp. 191–206). Notre Dame: University of Notre Dame Press.Find this resource:

Soulé, M. (1985). What is conservation biology? BioScience, 35(11), 727–734.Find this resource:

Soulé, M. (1990). The onslaught of alien species, and other challenges in the coming decades. Conservation Biology, 4(3), 233–239.Find this resource:

Soulé, M., Gilpin, M., Conway, W., & Foose, T. (1986). The millenium ark: How long a voyage, how many staterooms, how many passengers. Zoo Biology, 5, 101–113.Find this resource:

Stanley Price, M. R., & Fa, J. E. (2007). Reintroductions from zoos: A conservation guiding light or a shooting star? In A. Zimmermann, M. Hatchwell, L. Dickie, & C. West (Eds.), Zoos in the 21st century. Catalysts for conservation (pp. 155–177). Cambridge, U.K.: Cambridge University Press.Find this resource:

Steffen, W., Crutzen, P. J., & McNeill, J. R. (2007). The Anthropocene: Are humans now overwhelming the great forces of nature? Ambio, 36(8), 614–621.Find this resource:

Steffen, W., Persson, A., Deutsch, L., Zalasiewicz, J., Williams, M., Richardson, K., et al. (2011). The Anthropocene: From global change to planetary stewardship. Ambio, 40(7), 739–761.Find this resource:

Tribe, A., & Booth, R. (2003). Assessing the role of zoos in wildlife conservation. Human Dimensions of Wildlife, 8, 65–74.Find this resource:

Veasey, J., & Hammer, G. (2010). Managing captive mammals in mixed-species communities. In D. G. Kleiman, K. Thompson, & C. Kirk Baer (Eds.), Wild mammals in captivity. Principles and techniques for zoo management (2d ed., pp. 151–161). Chicago: University of Chicago Press.Find this resource:

Wirtz, P. H. (1997). Zoo city: Bourgeois values and scientific culture in the industrial landscape. Journal of Urban Design, 2(1), 61–82.Find this resource:

World Association of Zoos and Aquariums (WAZA). (1993). Executive summary of the world zoo conservation strategy—the role of the zoos and aquaria of the world in global conservation. Gland, Switzerland: WAZA.Find this resource:

World Association of Zoos and Aquariums (WAZA). (2005). Building a future for wildlife—The world zoo and aquarium conservation strategy. Gland, Switzerland: WAZA.Find this resource:

Zimmerman, A. (2010). The role of zoos in contributing to in situ conservation. In D. Kleiman, K. Thompson, & C. Kirk Baer (Eds.), Wild mammals in captivity. Principles and techniques for zoo management (2d ed., pp. 281–287). Chicago: University of Chicago Press.Find this resource:


(1.) Early menageries also served other purposes than the demonstration of absolute dominion over the animal kingdom, such as animal worship (Egypt) and gladiatorial combat (Greece and Rome) (Reid, 2016).

(2.) In fact, this shift in focus had already taken place in the United States at the turn of the 19th centrury, when the first zoos were built amid growing concern over the destruction of wildlife and the decline of wilderness (Wirtz, 1997, p. 70; cf. Minteer et al., 2016).

(3.) The establishment of the modern zoo depended on technological advancements of the Industrial Revolution. Founding fellow of the London Zoo Humphry Davy, a British chemist best known for his invention of the Davy lamp, a device that greatly improved safety for miners in the coal industry, was responsible for the zoo’s industrially heated piped water and plate glass, which “made it possible for the exotic and the savage to be imported into the midst of city life” (Schama, 1995, p. 560). The modern zoo was able to attract a large audience due to the fact that the Industrial Revolution provided leisure time for the masses, which began looking for entertainment in open areas that were no longer easily accessible since they moved to increasingly urban environments.

(4.) For a discussion of the different stages of the Anthropocene, see Corlett 2015 (cf. the article “The Anthropocene” from the Oxford research encyclopedia of environmental science).

(5.) “The indigenous range of a species is the known or inferred distribution generated from historical (written or verbal) records, or physical evidence of the species’ occurrence” (IUCN/SSC, 2013, p. 2).

(6.) For examples, see Hutchins and Wemmer (1986); and Hutchins (2007).

(7.) This is also true for Martha Nussbaum’s capabilities approach. Although this approach, in contrast to most other approaches to animal ethics, does attach ethical and political significance to species membership as such, it nonetheless adheres to a liberal individualist framework.

(8.) According to Dale Jamieson “the notion of a species is an abstraction; the idea of its welfare is a human construction. While there is something that it is like to be an animal there is nothing that it is like to be a species” (Jamieson, 1995, p. 61).

(9.) The list cites 1,140 species of mammals; 1,313 species of birds; 847 species of reptiles; 1,948 species of amphibians; and 2,110 species of fish.

(10.) In North America, more people visit zoos and aquariums than all major sports (baseball, basketball, hockey, and football) combined (Routman et al., 2010, p. 137).