In a study published this week in the journal Science, zoologist Georgia Mason, of the University of Guelph in Canada, and colleagues drew on 45 years of data on more than 4,500 African and Asian elephants worldwide. The elephants studied lived in European zoos, a wildlife preserve in Kenya, and a Burmese enterprise that uses elephants to harvest timber. Most of the elephants were female.
The results were shocking. Ms. Mason and her colleagues found that, excluding premature and still births, zoo-born African elephants had a median life span of 16.9 years, compared with 56 years for animals in the park. Asian elephants, which are more endangered than their African counterparts, lived for 18.9 years in captivity and 41.7 years in the Burmese timber trade.
The study further noted that Asian elephants had far higher infant mortality rates in zoos, a problem that the authors say had "not significantly improved over time."
Overweight and stress
The likely causes of these shortened lifespans should be familiar to Americans: obesity and stress. Overweight pachyderms are found to be prone to cardiovascular disease. As for stress, the researches found that being moved among zoos and being separated from their mothers put the animals at greater risk.
Infanticide is almost unheard of among wild elephants. Mothers invest two years in their pregnancies, they live in stable matriarchal groups, and females collectively care for the young. In captivity, mothers are often held in relative solitude, undergo stressful and painful births, and then simply kill the source of all that suffering. Some mothers, Mason says, may even turn to infanticide because they just don't know what the small, squirmy creature that suddenly appeared in front of them is. "Many females in zoos have never seen a calf," she says, "so they may not recognize it."
The authors do not advocate an outright ban on elephant captivity; rather they recommend screening the animals for obesity and signs of stress. A press release from the University of Guelph notes:
Until these animals’ problems can be solved, the researchers also call for an end to the importation of elephants from their native countries, the minimizing of inter-zoo transfers, and suggest that breeding elephants should be restricted to those zoos that exhibit no harmful effects in their captive-born animals.
Report charged with bias
The study is not without its detractors. The New York Times quotes Peter Boyle, the senior vice president for conservation and education at the Association of Zoos and Aquariums, who calls the report “terribly flawed” and driven by an antizoo agenda. Mr. Boyle, an environmental biologist, took issue with the authors' use of data going back to 1960, saying that zoo conditions have improved dramatically.
“If you were looking at the success of heart transplants and you reached back 48 years, you would be obviously biasing the success rate,” he told the Times.
"This is about elephants in Europe,” he told the LA Times. “There are wonderful zoos in Europe and there are zoos that are not so wonderful.”