英语听力：自然百科 秋日黄石公园 Autumn—11

Groves of aspen/ all turn at the same time, each grove descended from one tree interconnected by roots, color coordinated. As cold air sinks further down from the mountains, it brings autumn mist to Yellowstones valleys. It was in the autumn of 1870

英语听力：自然百科 秋日黄石公园 Autumn—10

In just a few weeks, this lake will be frozen, and the beavers wont be able to cut and move trees, but they will be able to swim right under the ice to feed from this underwater larder. Moose also eat twigs and branches and often try to take advantag

英语听力：自然百科 秋日黄石公园 Autumn—13

To stay is to face the certainty of snow and wolves. To go offers the chance of an easier life, but the uncertainty of the world beyond Yellowstone. Every autumn, thousands of elk do leave Yellowstone, and as they go, they cross an invisible line out

英语听力：自然百科 秋日黄石公园 Autumn—2

All over Yellowstone, male elk are challenging each other for dominance. The sound of Yellowstone's autumn. They're trying to win the admiration of females and gather them into a hareem, only then do they stand a chance of mating with them before win

英语听力：自然百科 秋日黄石公园 Autumn—9

It cuts branches into more manageable lengths and then swims them down a network of purpose-built canals towards the dam. The pond to give this beaver protection from predators, and the canals allow it to forage far into the forest, carrying many tim

英语听力：自然百科 秋日黄石公园 Autumn—8

They may be a little safer here. But the food in the forest is far less nutritious than on the riverbanks. If they want to eat well and avoid wolves this winter, they'll need to keep on moving. As the elk move gradually downwards, they follow the riv

英语听力：自然百科 秋日黄石公园 Autumn—7

Its now September, and the elk/ have made their way down to graze where the grass on the riverbank is still green, and they can browse the nutritious shoots of young willow trees. The males are now upping their game. This bull urinates on himself to

英语听力：自然百科 秋日黄石公园 Autumn—6

Up to 150 at a time, a fifth of its entire body weight. Then it flies as much as 15 miles away, and drills the nuts into the ground in sets of ten, placing a stone on top of the stash to mark the site. It goes back for more and more. Over the autumn,

英语听力：自然百科 秋日黄石公园 Autumn—5

But this is not much good for the tree. Its seeds have gone nowhere. A grizzly bear mother and cubs. It's unusual for a grizzly to have so many cubs. This mother has found two orphans, and adopted them. But now she has four cubs to fatten up before t

英语听力：自然百科 秋日黄石公园 Autumn—4

But as many are preparing to get out, some have no choice but to stay. In the remote northeast of the Yellowstone wilderness, are the Beartooth Mountains. Here, surviving about 8,000 feet, a tree now welcomes the change of / season, the white-bark pi

英语听力：自然百科 秋日黄石公园 Autumn—3

The sun has revitalized this place, and now there are more living things here than at any time of the year. The summer has brought visitors too who are enjoying Yellowstone at its most vibrant. As the sun now starts to get lower in the sky, the rich

英语听力：自然百科 秋日黄石公园 Autumn—1

Yellowstone, volcanic wonderland, two million acres of wild space, right in the heart of North America. The heat of the summer has unveiled the full extent of the Yellowstone wilderness, and for a few precious months it has blossomed. But now, Yellow

英语听力：自然百科 黄石公园的夏天 Yellowstone—19

As she approaches to see him off again, she realizes she has been injured. A damaged jaw would be a disaster for her and her family. Clearly in pain, she leads the anxious cubs to high ground away from the male. She nurses to calm and / reassure them

英语听力：自然百科 黄石公园的夏天 Yellowstone—18

But just as the first of Yellowstone's new generation are preparing to leave, its last visitors are arriving. Night after night, army cutworm moths have been escaping the heat of a distant prairie. They have been flying in on favorable winds, hiding

英语听力：自然百科 黄石公园的夏天 Yellowstone—16

Bison calves are more independent of their mothers. The adults' focus is now set on a ruthless competition to mate. A male bids to enter a herd with females in season. He uses dust to accentuate all his size and power. Another male already establishe

英语听力：自然百科 黄石公园的夏天 Yellowstone—15

As the thaw reaches up into the mountains, a part of Yellowstone that few ever see is briefly revealed. From its first day above the snow, this pika is obsessed by food. It's in a frantic race to restock its winter larder before the snow closes in ag

英语听力：自然百科 黄石公园的夏天 Yellowstone—14

Bison lose the last of their winter coats. In the heat, tempers fray. To escape soaring ground temperatures, cowbirds choose a bison's back as a cool place to feed and catch the breeze. Biting insects now become a draining nuisance. A grizzly bear es

英语听力：自然百科 黄石公园的夏天 Yellowstone—17

They are vast smoke plumes. Yellowstone is burning. Throughout the summer, the dry lodgepole pines have become like a tinderbox, and lightening has struck the match. The worst wild fires will burn for weeks. In 1988, a third of Yellowstone burnt in a

英语听力：自然百科 黄石公园的夏天 Yellowstone—13

She chews its tail first, to make sure the fish can't get away. While the pups are still demanding milk, the mother otter will often keep the whole fish for herself. Her pups are happy enough with caviar. As the flow becomes slow enough for the trout

英语听力：自然百科 黄石公园的夏天 Yellowstone—12

This female grew up on the lake, so she knows where to take the cubs for a very special trip. Yellowstone cutthroat trout are massing in the mouth of the stream that feeds the lake. They are preparing for their annual spawning. But the trout must wai