5 Arguments for Zoos, Fact-Checked and Unpacked

Zoos are one of the oldest forms of entertainment on Earth, with the earliest records of their existence dating back to 1,000 BC. They’re also incredibly polarizing and controversial. Proponents for zoos argue these institutions have a positive impact on humans, animals and the environment. But the full picture is far more complicated, and it’s worth unpacking the arguments for zoos in order to understand why.

Before getting into the weeds, it’s crucial to point out that not all zoos are created equal. Around 235 zoos worldwide are accredited by the Association of Zoos and Aquariums (AZA), out of the many thousands that exist around the globe (10,000 according to a widely cited AZA figure, though that figure is at least a decade old). The AZA requires its zoos to regularly study their animals for research purposes and abide by strict animal welfare standards. These standards include, but aren’t limited to:

• Providing enclosures that promote the physical, psychological and social wellbeing of the animals
• Grouping members of a species together in a manner that reflects their natural social tendencies
• Providing multiple different areas within each animal’s environment
• Providing enough shade to avoid direct sunlight on sunny days
• Regular observation of animals’ physical health
• A 24/7 veterinary program directed by a qualified veterinarian that focuses on disease prevention and animal welfare

Because of these standards, animals seem to be treated much better in AZA-accredited zoos than other zoos, and better conditions for zoo animals tend to be found mainly or entirely in those with AZA accreditation.

Unfortunately, just 10 percent of zoos in the U.S. are accredited by the AZA according to the organization, and as such, the vast majority of zoo animals are vulnerable to mistreatment.

Argument 1: “Zoos rehabilitate sick and injured animals”

It’s true that some zoos provide sanctuary and rehabilitation for animals  who are sick, injured or otherwise unable to survive on their own, and that AZA-accredited zoos work with the U.S. Fish and Wildlife Service to care for sea animals. In addition, because zoos are predator-proof, prey species that aren’t even part of zoos will sometimes seek refuge in them.

But if we’re going to talk about animal welfare in zoos, we have to look at the entire equation, not just a single element — rehabilitation programs — that happens to benefit animals.

A 2019 report from World Animal Protection found that hundreds of zoos actively abuse their animals in order to provide entertainment for visitors. Animals were forced to undergo extensive and painful “training” in order to learn how to perform activities that visitors find amusing. Examples of such activities include dolphins being forced to act as surfboards, elephants being forced to swim underwater and wild cats being forced to perform in gladiator-style shows.

Zoo animals can suffer physically in more indirect ways as well. For instance, an estimated 70 percent of gorillas in North America — all of whom are in captivity — have heart disease, which is alarming, given that heart disease is nearly non-existent among wild gorillas. The culprit for heart disease in gorillas may be a diet of biscuits that doesn’t address the specific nutritional needs and  ease of digestion met by their diet in the wild, which tends to be mostly leafy fibrous greens. African elephants live three times longer in the wild  than in zoos, and there are countless stories of zoo animals being killed or maimed due to irresponsible humans around them.

We also have to look at the psychological effects zoos have on animals. Many zoo animals don’t have nearly enough space to live comfortably, and this can drive them insane; captive polar bears, for instance, are given just one-millionth of the space they’d normally have in the wild. Severe space restrictions like this cause zoo animals to engage in unnatural, repetitive and often harmful behaviors, such as pacing in circles, plucking out their own hair, biting the bars of their cages and even eating their own vomit or feces.

This affliction is so common that it has a name: zoochosis, or psychosis caused by zoos. Some zoos attempt to combat it by providing animals with toys or puzzles to occupy their time, while others reportedly respond by giving their animals Prozac and other antidepressants.

Finally, there is the fact that zoos often kill “surplus” animals that they no longer have use for. Specifically, zoo animals are killed when they’re no longer profitable, or when they don’t have a place in the zoo’s breeding programs. It has to be stressed that these are often healthy animals. Although zoos generally don’t release their euthanization numbers, the European Association of Zoos and Aquaria estimates that between 3,000 and 5,000 zoo animals are killed every year in Europe alone.

Argument 2: “Zoos bring nearly-extinct species back from the brink”

Some zoos have bred endangered species in captivity and then released them into the wild, thus preventing them from going extinct. Many of these efforts have been quite successful: the California condor, the Arabian oryx, Przewalski’s horse, the Corroboree Frog, the Bellinger River snapping turtle and the Golden Lion tamarin were on the brink of extinction before being saved by zoos.

Make no mistake: these are positive developments, and the zoos that helped bring these species back deserve credit for their work. But it’s also relevant to note that, while some species have been saved from extinction by zoos, other species have actually gone extinct in zoos. The last remaining Carolina parakeet died in a zoo for instance, as did the last dusky seaside sparrow and the last quagga. The thylacine, a fox-like marsupial native to Tasmania, went extinct in a zoo due to suspected neglect by the zookeepers.

In addition, one zoo in Zimbabwe has been found to poach elephants from the wild, often when they’re newborns. Ultimately, most animals that are born in zoos are never released into the wild.

Argument 3: “Zoos encourage children and the public to take a stronger influence in animal welfare and conservationism”

Although it’s difficult to measure this in any scientific sense, some researchers have argued that coming face-to-face with animals in zoos results in attendees forming closer emotional bonds with animals, and that this may prompt some of them to enter fields related to animal care or conservation. Many zoos offer education programs, for children and adults alike, that can further encourage people to play a more active role in animal care, conservation and environmentalism.

This claim is controversial, however. It comes in part from a 2007 study released by the AZA, which concluded that “going to AZA-accredited zoos and aquariums in North America does have a measurable impact on the conservation attitudes and understanding of adult visitors.” However, the overwhelming majority of zoos in the world are not AZA-accredited, so even if the study’s findings were accurate, they’d only apply to a small minority of zoos.

Furthermore, a subsequent third-party analysis concluded these findings might not be accurate in the first place, due to multiple methodological flaws in the AZA study. That analysis concluded that “there remains no compelling evidence for the claim that zoos and aquariums promote attitude change, education, or interest in conservation in visitors.”

However, subsequent research has suggested that the AZA’s initial study may have had some truth to it, with some studies offering evidence that people who visit zoos display higher levels of sympathy for animals and conservation efforts than non-visitors. This conclusion is hampered, however, by a correlation-causation problem; it’s possible that people who choose to visit zoos are already more animal-friendly than those who don’t, and that the zoo itself played no role in shaping their attitudes. Studies on this topic frequently note that more research is needed to draw a firm conclusion.

Argument 4: “Zoos contribute scientific research into animal welfare and conservationism”

According to the organization’s website, all AZA-accredited zoos in the U.S. are required to observe, study and research the animals they house in order to advance our knowledge of how to best conserve and protect them. Between 1993 and 2013, AZA-accredited zoos published 5,175 peer-reviewed studies, mostly focused on zoology and veterinary science, and the organization publishes a comprehensive report every year on the research efforts its member organizations have funded.

Still, only a small percentage of zoos are AZA-accredited. Many zoos have no such programs, and the majority of zoos aren’t required to have them.

It’s also a bit ironic to credit zoos with advancing scientific knowledge of animals when many zoos, in practice, actively ignore such knowledge. For example, zoos don’t allow their animals to maintain the complex, natural social hierarchies that they’ve evolved to survive. Due to their confinement, zoo animals can’t develop relationships with one another in the way they would in the wild, and are often abruptly removed from their social groups or families and shipped to other zoos (if they aren’t born in confinement). When a new animal arrives at a zoo, they are often “rejected” by other members of their species, which can often lead to violence between them.

Argument 5: “Zoos help track diseases before they reach the public”

This did happen, exactly once, 25 years ago. In the early stages of a West Nile virus outbreak in 1999, public health officials first became aware that the virus had reached the Western hemisphere when staff at the Bronx zoo informed them that they’d detected it in the zoo’s birds.

This is anything but typical. What’s much more common, in fact, is humans catching diseases from zoo animals. E. coli, Cryptosporodium and Salmonella are among the most common; these are known as zoonotic diseases, or diseases that can be passed from non-humans to humans. According to the CDC, there were 100 outbreaks of zoonotic diseases between 2010 and 2015 that originated in zoos, fairs and educational farms.

The Bottom Line

Zoos are certainly more oriented towards animal welfare now than they were at their inception many centuries ago, and there are some efforts to continue that progress. One is the “unzoo” concept, an attempt to invert the traditional zoo model by creating enclosed areas for humans in animals’ natural habitats, rather than the other way around. In 2014, a tasmanian devil conservation park was converted into the world’s first unzoo.

Nevertheless, the fact remains that a great number of animals suffer daily as a result of standard zoo practices, and while the accrediting body for zoos — the AZA — has some stringent requirements for its member zoos, the overwhelming majority of zoos aren’t part of the AZA, and have no independent oversight and no educational, research or rehabilitation requirements.

In an ideal world, all zoos would have humane policies on the books, and all zoo animals would enjoy long, healthy and happy lives. Unfortunately, that’s not the world we live in, and as it stands, any claims as to the virtue of zoos need to be taken with a heavy grain of salt.

Update: This piece has been updated to note that an account regarding Gus the polar bear being fed Prozac was reported in some (but not all) news outlets that covered the animal.