英语听力:自然百科 北极熊 冰上间谍 Spy_Bear—11(在线收听

 Back on Svalbard, it's high summer. Barnacle geese that had overwintered in Scotland have started to breed. Their calls bring hope to hungry bears. The cub stays back as his mother explores the possibilities.

 
Bears have only recently discovered this new source of food, seeking out colonies that nest on the ground rather than on cliffs. The eggs are a rich source of protein. Just 250 are as nutritious as one ringed seal. She carefully picks up an egg in her jaws before swallowing its contents. The geese launch an attack. 
 
Some have goslings, a bite-size snack for a bear. In just one day, one bear can devour over 1,000 eggs and hatchlings, destroying a whole colony. But as the threat escalates, so does the defense.
 
Arctic skuas join the attack. A skua lands a direct hit. She's had enough.
 
In future, the birds will have to start nesting on cliffs to avoid polar bear attacks.
 
Skuas may have saved the colony this time, but they've made the bears' lives a lot more difficult. 
 
Further north from Svalbard, other landlocked bears have found a more reliable meal, a carcass of a stranded fin whale. Icebergcam investigates the happy gathering. The whale is 24 meters long and weighs 60 tons, an once-in-a-lifetime feeding opportunity. An adolescent eats confidently alongside four adult bears.
  原文地址:http://www.tingroom.com/lesson/zrbaike/2010/259535.html