Forests Are Helped by Animals

1. Animals depend on the forest but sometimes the forests are helped by animals. Once beavers caused trouble to Arizona fruit growers. The beavers made dams on the irrigation ditches. This kept water from flowing to the fruit trees where it was needed. But worst of all was that the beavers were building their dams out of fruit trees logs. The farmers trapped some five hundred beavers and let them free near mountain streams far up in the forest. There the beavers went to work building dams again. But this time the dams slowed up fast moving mountain streams, held the water for for­ests and cut down erosion. Beavers have been parachuted down into wild country where they have helped control streams which men visited only from the air..

2. Beavers are intelligent animals. Their dams are fine examples of engineering. A pair of beavers constructs a dam across a river. The water held back by the dam-overflows the bank on either side of the river, forming a pond. In this pond the beavers build home. It is built of branches and sticks held together with mud and stone.

3. From the point of view of engineering their small house can hardly be improved.

4. It contains a central room Just above the water level, it has one or more entrances under the water, strong walls and even a vertical chimney, which regulates the temper­ature inside and provides air-conditioning. A beaver fam­ily—father, mother and several young ones—live to­gether in their house.

5. The engineering skill of beavers is to a large extent a result of their ability to use their front paws as hands.

6. Trees are essential to beavers. They eat the bark on the upper branches and in order to reach these they must fell the trees. Tree-felling is a skilled job but a pair of beavers can fell a tree four inches in diameter in 15 minutes.

7. It is easy, therefore, to see why people talk about the beaver's skill and intelligence. However, the structure of beaver's brain gives no indication that the animal is more intelligent than some others. Many of his actions which seem to be the result of thinking are due to instinct.

II Прочтите 6-ой абзац текста и письменно ответьте на следующий вопрос:

What must beavers do in order to reach the bark of a tree?

Контрольная работа № 5

(для специальностей ЛХФ)

Вариант 4

Дата добавления: 2015-07-11