英语论文网

Most people think of zoos as safe places for animals, where straggles such as difficulty finding food and avoiding predators don't exist. Without such problems, animals in zoos should live to a ripe old age1.

But that may not be true for2 the largest land animals on Earth. Scientists have known that elephants in zoos often suffer from poor health. They develop diseases. joint problems and behavior changes. Sometimes, they even become infertile, or unable to have babies.

To learn more about how captivity affects elephants, a team of international scientists compared the life spans of female elephants born in zoos with female elephants living outdoors in their native lands. Zoos keep detailed records of all the animals in their care, documenting factors such as birth dates, illnesses, weight and death. These records made it possible for the researchers to analyze 40 years of data on 800 African and Asian elephants in zoos across Europe. The scientists compared the life spans of the zoo-born elephants with the life spans of thousands of female wild elephants in Africa and Asian elephants that work in logging camps3, over approximately the same time period.The team found that female African elephants born in zoos lived an average of 16.9 years. Their wild counterparts who died of

natural causes lived an average of 56 years — more than three times as long. Female Asian elephants followed a similar pattern. In zoos, they lived 18.9 years, while those in the logging camps lived 41.7 years.

Scientists don't yet know why wild elephants seem to fare so much better than their zoo-raised counterparts. Georgia Mason, a biologist at the University of Guelph in Canada who led the study, thinks stress and obesity may be to blame4. Zoo elephants don't get the same kind of exercise they would in the wild, and most are very fat. Elephant social lives are also much different in zoos than in the wild. where they live in large herds and family groups.

Another finding from the study showed that Asian elephants born in zoos were more likely to die early than Asian elephants captured in the wild and brought to zoos. Mason suggests stress in the mothers in zoos might cause them to have babies that are less likely to survive.

The study raises some questions about acquiring more elephants to keep in zoos. While some threatened and endangered species living in zoos reproduce successfully and maintain healthy populations, that doesn't appear to be the case with elephants.

"Currently, zoos are net consumers of elephants ,not net producers." Mason says.

1. According to the first two paragraphs, unlike other zoo animals, zoo elephants根据前面2段，和其它动物不同，动物园的大象

_____________

A. have difficulty eating food.吃东西有困难。

B. live to a ripe old age.能过活到高龄。

C. are not afraid of predators.不害怕食肉捕食者。

D. develop health problems. 面临一些健康问题。(正确答案)

2. Which of the following about the international scientists' research on the life spans of elephants is NOT true? (See

paragraph 3)? 国际科学家对于大象的生命周期的研究，______________是不对的?

A. They compared zoo elephants with wild elephants.他们把动物园的大象和野生大象作比较。

B. They kept detailed records of all the elephants in their care. 他们保留了饲养大象的详细记录。(正确答案)

C. They analyzed the records of the elephants kept in zoos.他们分析动物园里的大象的生活记录。