No Place Like Home – Housing of Great Apes in Zoos

Free-living great apes occupy diverse habitats and areas of multiple square miles across their natural ranges, depending on species. Orangutans spend the majority of their time in the trees, for which their long arms and strong grasping hands are perfectly adapted. Chimpanzees and bonobos split their time between trees, where they forage for food, and the ground, which they use for travelling. Due to their large body sizes, gorillas are better adapted to ground dwelling and spend very little time climbing.

Gorillas, chimpanzees, bonobos, and orangutans all build nests for sleeping. Orangutans, in particular, use intricate weaving and construction techniques. Chimpanzees and bonobos choose to nest on the ground or in trees depending on the terrain and their preference, and gorillas tend to nest on the ground. All species of great ape may travel multiple miles in one day, often building sleeping nests from scratch each night. Chimpanzees and bonobos live in what are known as “fission-fusion societies” which means that, while there is one larger community, that community changes in structure, splitting into smaller groups and coming together again. These changes are driven by food availability, terrain, climate and weather, familial relationships, mating availability, friendships, and conflicts.

None of these complex environmental and behavioral needs can be met when great apes are held captive in zoos.

Zoo Captivity Robs Great Apes of the Chance to Live Out Natural Behaviors

Zoo enclosures are many magnitudes smaller than natural home ranges for great apes. This has detrimental consequences for the health of great apes confined within. Zoo industry guidelines recognize that it is “difficult to encourage gorillas to exercise in a confined area such as a zoo enclosure” which can result in individuals becoming obese. Even those built in recent years, or still under construction at the time of writing, fail to meet the special requirements of these complex animals. For example, San Antonio Zoo in Texas has promoted the construction of “Congo Falls,” a new gorilla exhibit, due to open in 2025. Described as a two-acre exhibit (0.003 square miles), it is 900 times smaller than the smallest home range of free-living gorillas. The new enclosure is due to house eight gorillas split into two groups. It is unclear if the full area will be useable space for the apes, or if it also includes the visitor space.

Zoo Enclosures Are Far Too Small to Meet Apes’ Needs

A chimpanzee exhibit that opened at the Indianapolis Zoo in 2023 has a footprint of just 0.22 acres (0.00034 sq miles). This is 3,666 times smaller than the smallest natural chimpanzee range and 80,000 times smaller than the largest reported natural home range. The exhibit, which is home to 21 chimps, cost $25 million USD to build.

Henry Doorly Zoo in Omaha, NE, opened its new orangutan exhibit in 2024. Four orangutans live in the 0.05 acres (0.000082 sq miles) space which was described as “innovative and forward-thinking.” The enclosure is 16,463 times smaller than the smallest recorded orangutan home range. The enclosure cost $21 million USD to build.

A 2016 citizen survey found median enclosure size for gorillas in 28 zoos in the United States to be 0.4 acres (0.00065 square miles). The smallest was just 0.056 acres (0.000089 square miles and the largest was 1.28 acres (0.002 square miles). The same survey found that the median chimpanzee enclosure in the same zoos was 0.26 acres (0.0004 square miles). The smallest enclosure was 0.04 acres (0.000061 square miles) and the largest was 2.6 acres (0.0041 square miles). Orangutans in zoos had a median living space of 0.14 acres (0.00022 square miles). The smallest orangutan enclosure was 0.064 acres (0.0001 square miles) and the largest was 1.2 acres (0.0019 square miles). It is unclear whether or not the survey took into account only space usable by the animals, or if it also included visitor infrastructure. As such, these figures should be considered the maximum space animals have access to.

Zoo Enclosures Are Designed with the Zoo’s Interests, not the Animals’, in Mind

In addition to size limitations, great ape housing in zoos is often designed with the zoo’s convenience as paramount. For example, in a 2021 study of AZA zoos, 29 of the 42 zoos surveyed (69%) exclusively housed their apes on hardscape floors such as concrete. This is likely because concrete is easier to clean than more complex, natural substrates.

Gorilla conservationists have expressed frustration over the extortionate amounts of money invested by zoos in holding great apes captive. In 2007, when London Zoo invested £5.3 million GBP on a new gorilla exhibit, gorilla expert, United Nations’ chief consultant on great apes, and Born Free consultant, Ian Redmond said: “£5m for three gorillas [seems a huge amount] when national parks are seeing [three gorillas] killed every day for want of some Land Rovers, trained [people] and anti-poaching patrols. It must be very frustrating for the warden of a national park to see.”

It Is Time to End Great Ape Zoo Captivity

Enclosure size and construction has a direct impact on ape welfare in zoos. Negative impacts include the inability to demonstrate natural behaviors, being forced into close proximity with conspecifics which creates social tension, increases chances of conflict and resulting injuries, exacerbates potential for disease spread between individuals, and prevents adequate physical movement resulting in obesity and other issues. All of these factors negatively impact the mental and physical health and welfare of animals.

Born Free is calling upon the zoo industry to phase out the captive keeping of great apes and encourages members of the public to support in situ conservation efforts in the animals’ native habitats.

Learn more about the plight of great apes in zoos with our latest report, Our Captive Cousins.

Keep Wildlife in the Wild,

Liz