美国有线新闻 CNN 世上仅存雄性北方白犀牛被实施安乐死 物种濒临灭绝（在线收听）

With the weight of between three and five tons, the white rhinoceros checks in as the planet's second largest land mammal.

AZUZ: And the sub species of the white rhino known as the northern white rhino is now just two animals away from complete extinction and both of the living ones are females. The last male who was named Sudan lived on a conservancy in the African nation of Kenya. He was 45 years old, which is elderly for a rhinoceros and he had a lot of health issues related to his age. So, a conservation group announced yesterday that Sudan had been put to sleep.

As Sudan lived out his last years, he was protected 24 hours a day by armed guards. Just as conservationists prized Sudan for being the last male northern white rhino, poachers, people who illegally kill animals, prized rhinos for their horns because especially in Asia, they're believed to cure different problems in humans.

Researchers have saved some of Sudan's DNA and they're hoping to use it to keep the sub species alive. If they're unsuccessful, they say the two remaining female northern white rhinos will probably die over the next decade, making these unique animals extinct.

ARAI SEVENZO, CNN CORRESPONDENT: He just couldn't carry his weight anymore. I mean, these beasts you see behind me, one of them is his daughter, Fatu, his granddaughter, I beg your pardon, and his daughter, Najin, are over there. They're the two only northern white rhinos, which is distinct from the southern white rhinos because they have shorter legs, heavier ears.

But basically, Sudan was the last male rhino. And because of crippling old age, he could no longer carry himself. And we've spoken to the vets here and the feeling, while you're asking, is one of sadness, as if they really lost someone they knew for a long time and they did know him for a long time.

Born in 1973, many of his relatives were massacred and killed mainly for their horns in poaching, in this part of the world. And at the moment, they're trying, the scientists and the conservationists, to find some way of conserving Sudan's lineage by an incredible, fascinating system of harvesting the eggs of the last two females here. This is absolutely sort of cutting edge of science and conservancy.

So, all is not lost, but, of course, the blame has to go to us, as people and mankind. Remember, rhinos have been on this earth for 55 million years and it took out two centuries to wipe out a complete sub species of the northern white rhinos.