Zoo elephants don’t live as long as those in the wild, according to a study sure to cause debate about keeping the giant animals on display. Researchers compared the life spans of elephants in European zoos with those living in Amboseli National Park in Kenya and others working on a timber enterprise in Buma. Animals in the wild or in natural working conditions had life expectancies twice than or more of their relatives in zoos. Animal care activists have urged in recent years to discourage keeping elephants in zoos, largely because of the lack of space and small numbers of animals that can be kept in a group. The researchers found that the median life span for African elephants in European zoos was 16.9 years, compared with 56 years for elephants who died of natural causes in Kenya’s Amboseli Park. Adding in those elephants killed by people in Africa lowered the median life expectancy there to 35.9 years. For the more endangered Asian elephants, the median life span in European zoos was 18.9 years, compared with 41.7 years for those working in the Burma Timber Enterprise. Median means half died younger than that age and half lived longer. There is some good news, though. The life expectancies of zoo elephants have improved in recent years, suggesting an improvement in their care and raising, but “Protecting elephants in Africa and Asia is far more successful than protecting them in Western zoos.” There are about 1,200 elephants in zoos, half in Europe, researchers concentrated on female elephants, which make up 80 percent of the zoo population. One amazing thing was that Asian elephants born in zoos had shorter life spans that those brought to the zoos from the wild. Zoos usually lack large areas that elephants are used to in the wild, and that zoo animals often are alone or with one or two other unrelated animals, while in the wild they tend to live in related groups of 8 to 12 animals. In Asian elephants, baby death rates are two to three times higher in zoos than in the Burmese logging camps, and then, in adulthood, zoo-born animals die young. People are not sure why. 小题1:What is argued about in this passage?
|