英语听力：自然百科 大迁徙之繁衍生息 Need to Breed—3

From tip to tip, its wings stand eight feet. This superb blighter can soar almost e* 24 hours a day. Waiting in this bustling, the troublous of hundreds of thousands of birds, her mate shores up the nest from last year's breeding. And after seven lon

英语听力：自然百科 大迁徙之繁衍生息 Need to Breed—4

An egg tumbled from the nest is fair game for Johnny rook. He'll soon have his own clamoring brood to look after. On another stretch of beach, the shoreline quakes with desperate battles to dominate. The stakes are unimaginably high. Only a privilege

英语听力：自然百科 大迁徙之繁衍生息 Need to Breed—5

Blood runs freely from slashed noses and necks. They even fight dirty, going for the eyes. The loser's breeding chances for now are ground into the sand. But this beachmaster's triumph is just the beginning of his troubles. Ahead lie dozens of fights

英语听力：自然百科 大迁徙之繁衍生息 Need to Breed—6

Parenting on the move is all about sacrifice. And in the forests of northeastern Australia, another great journey spurred by parental dedication is about to begin. On translucent tawny wings, a little red flying fox flaps homeward after a night of in

英语听力：自然百科 大迁徙之繁衍生息 Need to Breed—7

But they can't migrate to greener pastures until the last of the youngsters has been winged. So mother has become stingy and edgy. Readying for the migration ahead, she tongues oily secretions over every bit of her flight equipment. A bat's wings are

英语听力：自然百科 大迁徙之繁衍生息 Need to Breed—8

In the war-racked country of Sudan, lies Boma National Park, the largest intact savanna in East Africa. Mile upon mile of what looks like pristine wilderness unfolds. But much of this is an empty paradise. During the Sudan's decades of ruinous civil

英语听力：自然百科 大迁徙之繁衍生息 Need to Breed—9

By November, the blinding equatorial sun has turned their southern water holes into sucking mud, a trap for unwary youngsters and so they must move north toward permanent water. Their pace quickens with the male's need to reach their ancient battle g

英语听力：自然百科 大迁徙之繁衍生息 Need to Breed—10

The nursery lies at the heart of a twitching, thriving structure, built almost entirely of the aunts of themselves. Long legs stuck together with tussle cores. They are the scaffolding, bricks, and mortar of the nests. But theyve been in one place fo

英语听力：自然百科 大迁徙之繁衍生息 Need to Breed—11

Almost magically, they form a temporary nest of their own bodies. The larvae and food are taken into the nursery at its centre. Tomorrow they will do the whole thing again, marching for two to three weeks to reach fresh hunting grounds, where they ca

英语听力：自然百科 大迁徙之繁衍生息 Need to Breed—12

Unable to leave his harem to feed its seed, hes losing 50 pounds of blabber a day. All ready the albatross checks a hatching in staggering numbers downy and demanding with unending patience. The new mother waits for her mate to return for his far ori

英语听力：自然百科 野性俄罗斯之西伯利亚 Siberia—3

Fat, laid down last summer provides energy during the meager winter months, but not all will make it. Further north, another cold weather survivor truly clings to life, one of the rarest birds in the world, the critically endangered Siberian White Cr

英语听力：自然百科 野性俄罗斯之西伯利亚 Siberia—4

Even though the deer have a poor sense of smell, the musk manages to attract mates. Unfortunately, the human trade in musk glands has reduced the deer's numbers dramatically. And because only two thirds of the females have fawns each year, the popula

英语听力：自然百科 野性俄罗斯之西伯利亚 Siberia—5

They can afford to--adult ravens seem to lack natural enemies. Time for a quick brush-down and they're all done--well, almost. Before man took his first step, ancient killers roamed the earth. Unchallenged, they feared nothing, until Mother Nature in

英语听力：自然百科 野性俄罗斯之西伯利亚 Siberia—6

The Yakut are an ancient people, thought to have migrated north to Yukutia around 700 years ago. And while most have become urbanized, 400,000 still live as traditional nomadic herders. The herdsmen must get the animals to new grazing before the snow

英语听力：自然百科 野性俄罗斯之西伯利亚 Siberia—7

In spring, as the weather finally warms, the rivers begin to unlock. Broken-ice makes handy barges for lazy water fowl. But the gaps in the ice also give golden-eye ducks a chance to fish. Soon, they are hunting in force. They are not the only ones b

英语听力：自然百科 野性俄罗斯之西伯利亚 Siberia—8

The Siberia salamander is one of only a few species on the planet that can survive the deep freeze like this. Moving 15,000 km to Siberia's southern steppes, the landscape dramatically changes. Pine forests give way to what look like African plains.

英语听力：自然百科 野性俄罗斯之西伯利亚 Siberia—9

A male with his harem seems at peace. But even without hunters, the life of an alpha male is tense. A challenger comes. It takes over three years for a young male to grow the impressive adult horns which can spiral to 190 centimeters long and weigh u

英语听力：自然百科 野性俄罗斯之西伯利亚 Siberia—10

But he soon wises up. The thick neck absorbs the blows .The delicate brain is cushioned beneath the core of hollow horns. He defends his claim and relocates his harem. But one challenger won't give up so easily. They can crash at nearly 100 km/h. Eve

英语听力：自然百科 野性俄罗斯之西伯利亚 Siberia—11

Thousands of years of isolation turned them into a separate species. In the middle of the lake are the Ushkanyi islands. Here the seals form their colonies safe from human predation. After a dip in the lake, nothing beats a dry resting place on the l

英语听力：自然百科 野性俄罗斯之西伯利亚 Siberia—12

After spending a year or so as larvae under water, they transform into winged adults and take to the skies. The millions of tiny flies attract far bigger animals. As they hold a mass mating orgy along the banks of the lake, brown bears come to feed o