Skip to content





Zoos can help tiger conservation by breeding the endangered animals in captivity and studying their stress and hormone levels.

Zoos need to change

OPINION: To justify their existence, they must make conservation their top priority

Support sound science and smart stories
Help us make scientific knowledge accessible to all
Donate today

Lea en español

When I was young, my parents took us to a zoo: the kind where you could see animals locked up in cages. I remember looking in admiration at a pair of bears in a cage, stretching out their paws for food. Things have changed. My kids would be horrified to see animals in jail like that. Today, we expect animals to be held in more natural settings, and for zoos to do more to make the world a better place. In order to justify the animals’ captivity, we expect zoos to help with conservation.

Zoos can host great conservation work. Sometimes they act as a kind of Noah’s ark to hold and protect endangered animals. There are about 40 animal species listed as “extinct in the wild”; they exist mainly in captive collections, including at zoos. These collections are used for study, to start breeding programs and, when possible, to reintroduce the animals to the wild.

But not enough zoos do enough of this. I support the recommendation made by some researchers that zoos should assign at least 10 percent of their income to biodiversity conservation. Sadly, a 1999 study from the Association of Zoos and Aquariums showed an average expenditure of only 0.1 percent. That’s 100 times less.

Of course, some zoos do a lot. Perth Zoo in Western Australia, for example, reported in 1999-2000 that it spent more than US$1 million breeding seven threatened species for reintroduction (including the western swamp tortoise, the chuditch marsupial, and the striped numbat), compared with their income of nearly $6 million. In other words, they spent at least 18 percent of their revenue on conservation. According to a 2015 World Association of Zoos and Aquariums report, $350 million is raised annually for wildlife conservation by global zoos and aquariums. That’s about the same as what WWF International — one of the most famous institutions in biodiversity conservation — currently spends on conservation programs each year.

Zoos have helped to reintroduce plenty of animals to the wild, including the black-footed ferret in the US, Przewalski’s horse in Mongolia, the Guam rail (a flightless bird), and island fox of California’s Channel Islands. Zoos can also help during a crisis: When bushfires raged across Australia in the summer of 2019-2020, Zoos Victoria was part of a state-led response to help wildlife.

If zoos were totally dedicated to the function of conservation, we might expect them to mostly house threatened species. But it’s clear that almost all zoos host non-threatened species in much greater numbers. Many zoos are focused on the big mammals and birds that draw audiences and help the zoos to make money, including elephants and giraffes; quite a lot of zoos exist solely as an entertainment business. In this day and age, I say that’s inappropriate. The possible detriment to the individual animals’ welfare is too high a price to pay for entertainment alone.

That’s not to say that zoos shouldn’t be a business at all. The care and feeding of animals can be extremely expensive: Food expenses for mammals in England’s Chester Zoo (which houses tens of thousands of animals) exceed $700,000 per year. I believe that it’s worthwhile for zoos to open their doors to the public to recoup some of this money, and to keep animals beyond the ones they are breeding or studying for conservation reasons in order to attract interest and attention — so long as the animals are kept in morally acceptable conditions that guarantee their welfare.

Opening doors to the public, of course, has a second benefit: education. In the US, 183 million people went to zoos and aquariums in 2022; nearly ten times more than attended professional football games. The opportunity for education is huge. Yet a lot of people don’t bother reading educational signs. And while animal shows are popular and good at conveying information, they can also, controversially, involve animal training. Many studies show that people tend to retain knowledge about animals from zoo visits, but whether that translates into pro-environmental action is debatable.


It seems intuitive to me that visiting animals in real life helps to foster an appreciation for the natural world. Virtual-reality goggles and movies about wildlife are worthwhile, but not the same. A friend of mine who works in the Amazon puts it this way: “To love the jungle, you need to smell the jungle.” Full immersion in real-life environments is a powerful experience that’s hard to replicate.

Some zoos have adopted the promising One Plan approach, which encourages zoos to work in collaboration with researchers and local communities on conservation activities. One good example is Zoos Victoria’s conservation breeding program for the Australian eastern barred bandicoot.

All zoos should make conservation their top priority, which will inevitably be accompanied by education and research. Without that, a zoo becomes just a business: one the world would be better off without.

Support Knowable Magazine

Help us make scientific knowledge accessible to all


TAKE A DEEPER DIVE | Explore Related Scholarly Articles

More From
+dcterms_language:language/en -dcterms_type:topics/newsletter -contentType:Journal -contentType:Contributor -contentType:Concept -contentType:Institution
This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error