英语听力：自然百科 大迁徙之繁衍生息 Need to Breed—15

Some freshwater crocs try to snap them out of the air, others wait for fatal mistakes. But many more make it through. And after many hours on the wing, they find their new paradise, fresh, succulent eucalyptus at the highest bloom. At dawn, they sele

英语听力：自然百科 大迁徙之繁衍生息 Need to Breed—14

At the top, red eyed, yellow browed and full of spunk, they celebrate their ascent and reunion, and are quickly assorted by their ravenous chicks. Now, the earlier, the bigger the adults. More food is the chorus ringing out up and down the shores and

英语听力：自然百科 大迁徙之繁衍生息 Need to Breed—13

And the raptor executes his cool mercy.In the rolling surf, rockhoppers pop home with their garlics full. They take turns shuttling to the sea daily , having tibets of quilt to feed their growing chicks. Once ashore, the rockhoppers trade their long

英语听力：自然百科 冰冻星球 前往地球尽头—1

Over one third of our planet is frozen, and yet the icy worlds of the Arctic and Antarctic are as alien to most of us as the surface of another planet. They are places of superlatives, from ice caps that hold nearly 80% of our planet's fresh water to

英语听力：自然百科 冰冻星球 前往地球尽头—2

I am standing at the North Pole, the very top of the earth. Up here, it's easy to see why the Polar Regions are so cold. The sun never rises high enough in the sky to warm my back. And those rays that do strike the surface are mostly reflected back f

英语听力：自然百科 冰冻星球 前往地球尽头—3

A male polar bear is searching for a mate. Willing females are few and far between. And the sea ice some of which he travels will soon melt and vanished. He's running out of time to find the mate in this frost frozen desert. Ten miles ahead, a single

英语听力：自然百科 大迁徙之繁衍生息 Need to Breed—20

After months on awkward shores, they are going home. The young albatross fledglings left behind days ago, rave their engines on their necks, testing the force for the wings and hauling wings that will power them around the world. It is time to fly or

英语听力：自然百科 大迁徙之繁衍生息 Need to Breed—16

Tonight the newly winged young would join the feeding frenzy.They are now fully fledged members of the colony,ready to investigate the bounty of this land,and dark in the dusk with breathtaking numbers once again. Morning in Costa Rica ,and the army

英语听力：自然百科 大迁徙之繁衍生息 Need to Breed—17

Even fearsome wasps high in treetops, are no match for the implacable ants. They watch helplessly as their own larvae are stripped from their honeycomb cribs. Now, the porters take up their burdens, they carry the movable feast back to the unquenchab

英语听力：自然百科 大迁徙之繁衍生息 Need to Breed—18

Here and now, cub and cub, pound for pound. The bodies of the falling litter the battle field. The females approach to the victorious males willingly, and with a discerning eye. They gravitate to the i/ storm, knowing that only the fittest gladiators

英语听力：自然百科 大迁徙之繁衍生息 Need to Breed—19

There is no mistaking yet. She is ready to mate. Finally, the lover/ unites a bit briefly. After two months, the breeding season is over. It is time for the long track back to their southern feeding grounds, but the females carrying the next generati