Thirty-five per cent of all the great apes kept in zoos worldwide display abnormal behaviours as a result of inappropriate housing or husbandry approaches. But this should change for the better with the introduction of an index to measure their quality of life.
University of Queensland School of Animal Studies PhD student Amanda Fernie has researched zoo experts around the world and created a system designed to pinpoint where zoos need improvement in their care of chimpanzees, gorillas, orangutans and bonobos (pygmy chimps).
She has observed apes at Melbourne, Perth, Rockhampton and Taronga zoos and will visit New Zealand zoos in 2008.
Fernie surveyed 359 zoo experts online in 2005, and used their responses to create the Great Ape Husbandry Index.
The system scores zoos out of 100 percent based on the quality of its physical and social environment of its enclosures, as measured by 17 ranked factors.
She said the top three factors for keeping great apes are healthy were
– Appropriate social groupings
– Enclosure appearance (bland, natural or artificial)
– Group size – number of individuals
Some of the abnormal behaviours displayed by great apes internationally who are inappropriately housed or lack the right social contact with others of their kind include reingestion and regurgitation, pica, coprophagy, hair plucking, picking at wounds, self mutilation, eye gouging, increased aggression, and a range of stereotypic behaviours such as repeated circling, oral stereotypes or rocking.
While these behaviours are not generally are not done to such an extreme that they cause significant harm to the individual, increased aggression can be a problem for other animals.
Asked what is the best sort of enclosure for the apes, Fernie said respondents to her survey ranked “a stimulating and natural looking environment higher than an artificial yet stimulating environment. They also indicated that social structure is the most important attribute of captive great ape husbandry, followed by enclosure appearance and group size.”
Numbers housed and group size and gender ratio need to reflect the animals’ wild environment, she said, while being in numbers which the enclosure in question can house appropriately. Most zoos are aware of the social structure needs of their great ape populations.
“If chimpanzees are densely housed it causes increased aggression. [However] It is impossible to say what number of animals in an enclosure is best; for chimpanzees an enclosure housing anywhere between 5 and 100 individuals may be suitable.” This applies also to bonobos, she said.
On the other hand, adult male orangutans are generally housed alone. “However, as in the wild they do come across other individuals, it’s preferable if they do have some sort of contact (olfactory or visual) with other orangutans.”
Female orangutans are generally housed either alone or with their offspring. “It seems orangutans that are housed together are generally more active than those housed alone, however some individuals prefer being housed alone,” she noted.
The ideal social structure for gorillas is a silverback (adult male), a number of adult females, their offspring, and older sub-adult males.
While she had no data on how Australian zoos stack up against those from other countries, she said she hoped the index would be adopted by the zoo industry’s peak body, the Australasian Regional Association of Zoological Parks and Aquaria (ARAZPA) and later rolled out internationally.
“All zoos are accredited to minimum standards via ARAZPA, but the index raises the bar.
“The Great Ape Husbandry Index could be incorporated into the accreditation process or guidelines of zoological associations to ensure zoos are providing appropriate levels of husbandry for their captive great apes,” she said.
“The Great Ape Husbandry Index could also be used as a model to create indices for other species held in captivity and would allow zoos to compare their husbandry practices with other institutions around the world.”