英语六级听力练习：标准4.5(3)_大学英语听力

英语六级听力练习：标准4.5(3)

　　Predators, such as cheetahs and wild dogs, need a lot of space.

　　They need areas in excess of 10,000 square kilometers, if youre going to support what we call viable and sustainable populations of these species. They need very wide areas of connected habitat. Elephants and wildebeests can need areas in excess of tens of thousands square kilometers, particularly where youve got migratory systems, such as you have in the Serengeti, where the wildebeests will range across areas in excess of 20,000 square kilometers, she said.

　　Durant said one well-known fencing disaster occurred in the Kalahari. The fence was a veterinary cordon barrier. It was designed to separate wildebeests from cattle and prevent disease from being transmitted to cattle herds. What happened, she said, was the collapse of the wildebeest migrations in that region.

　　Instead of spending a lot of money to build and maintain fences, she said, invest that money in alternative approaches. These include improved animal husbandry, community-based crop protection, insurance programs and sensitive use of land to help prevent human-wildlife conflict.

　　The authors of the article do say fences can be valuable resources in some cases. They cited the protection of birds in New Zealand against foreign species -- and safeguarding wolves and lynx in Scotland.