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Do Zoos Shorten Elephant Life Spans?
11 December 2008 (All day)
Elephants are one of the top draws for zoos, which are the only places most of us get a chance to see the behemoths. But a new and controversial study in tomorrow's issue of Science suggests that captivity is so bad for female elephants' health and overall well-being that their life spans are less than that of half of those of protected populations in Africa and Asia. The data also indicate that captive-born Asian elephant calves are particularly likely to die young. The team has called for an end to zoos' acquisition of wild elephants and for limits on transfers of animals among zoos.
Already concerned about their elephants, many zoos in the United States and Europe are expanding or building new enclosures, or even deciding against exhibiting the great beasts altogether. Studies in the wild have documented the importance of roaming and family ties for these animals, which zoos with limited space often cannot provide. A sign that the animals aren't thriving is that "zoos are not able to maintain their elephant populations without importing new, wild-caught animals," says Ros Clubb, a wildlife biologist at England's Royal Society for the Prevention of Cruelty to Animals in London. Clubb and co-author Georgia Mason, a behavioral biologist at the University of Guelph in Canada, published a pilot, non-peer-reviewed study on this issue 6 years ago. It was fiercely and "rightly" criticized, they say, for its small data set and poor statistics--problems they say they have corrected with the new report.
For the new study, the researchers drew on data from European "elephant studbooks" and the European Elephant Group, which track the animals' life histories and transfers in captivity. Clubb and colleagues compared the median life spans of 800 elephants in European zoos with those of wild elephants in Kenya's Amboseli National Park and tamed elephants in Burma's Myanma Tiber Enterprise (MTE), a logging business. "We chose populations that are highly protected, as are zoo elephants," says Clubb. The team's analysis revealed that African zoo elephants had life spans of about 17 years, whereas those in Amboseli lived 56 years. The median life span for Asian zoo elephants was nearly 19 years, but at MTE it was almost 42 years. Death rates for infant Asian elephants were especially high in zoos.
Some of the zoo elephants' problems stem from the practices of removing young calves from their mothers and transferring females from one zoo to another, usually for breeding. Both practices break the animals' family ties and presumably cause mental stress. "In the wild, females always stay with their mothers; they never leave the herd where they're born," says Mason. Zoo elephants are often overweight as well, due to a lack of space in which to roam.
Some zoo directors, including Miranda Stevenson, director of the British and Irish Association of Zoos and Aquariums in London, applaud the study. The study is an additional prod, she says, to continue the efforts to improve the quality of life for zoo elephants. "It's a very sobering study," agrees Ron Kagan, director of Michigan's Detroit Zoological Society, who oversaw the transfer of his zoo's two elephants to a California sanctuary 5 years ago because of concerns about their well-being.
But others, including elephant conservationist Iain Douglas-Hamilton of the environmental group Save the Elephants in Kenya, worry that the paper presents an unrealistic image of elephants in the wild. "In most wild populations, human predation is the predominant form of mortality," he notes. Further, zoos "play a significant role in conservation by stimulating the interest of children and adults." Stevenson adds that the changes under way at zoos in the United Kingdom have already led to improvements, noting that "all five calves born in the last 5 years" are healthy. "I'd like to see a similar analysis 5 years from now, since we are all working to improve conditions for our elephants."