英语听力：冰河绿洲—17

Today, there is a group of larger visitors here, too. A herd of mastodons led by the matriarch have just returned from their annual migration hundreds of miles to the north.

Now the winter drought is over and the spring water has been topped up by recent rains.

Another group has also set up camp nearby, hunters, descendants of the first human settlers that entered the continent in the far north. Compared to the harsh conditions their ancestors faced, this place is paradise. Targets for the hunters' spears are plentiful.

Around the spring, lush vegetation attracts the giant ground sloth, too. Both mastodons and sloths are browsers. But the mastodons roam far and wide to find the kind of plants they need. The giant ground sloth isn't built to travel far, but it makes up for that by having a reach of a giraffe.

Its huge claws may also be used for self-defence, although even the most powerful predatorwould think twice before tackling so large a prey.

In any case, this female jaguar is little threat right now. Once she's quenched her thirst, she will find a shady place to doze in the heat of the day.