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第22章 How Animals Spend the Winter

The weather gets colder, days get shorter and leaves turn color and fall off the trees. Snow covers the ground in winter. People live in warm houses and wear heavy coats outside. Our food can be bought from the grocery store. How about the animals?

1. Migrate①

How different and amazing the animals’ means to get through the winter.Some of them “migrate.” That is to say, they travel to other places where the weather is warmer or they can find food.

Many birds migrate in the fall. Because the trip may be dangerous, some travel in large flocks.Other kinds of birds fly alone. Birds can fly very long distances. For example, the Arctic tern nests close to the North Pole in the summer. It flies south all the way to Antarctica in autumn. Again it returns north when spring comes.

Most birds migrate in a shorter distance. Birds also seem to have a compass in their brain for using the Earth’s magnetic field to navigate② like sailors once did, using the sun, moon and stars for direction.

There are a few mammals, like some bats, caribou and elk, and whales travel in search of food each winter. Many fish migrate. They may swim south, or move into deeper and warmer water.

Insects also migrate. Some butterflies and moths fly very long distance. But most migrating insects go much shorter distances. Manyanimals like termites and Japanese beetleswill move downward into the soil. Earthworms also move down as far as six feet below the surface.

2. Adapt

Some animals remain active in winter, but theymust adapt to the changing weather. Many make changes in their behavior or bodies. For example, animals may grow new, thicker fur in the fallto keep warm. For snowshoe rabbits, the new white fur helps them hide in the snow.

It is hard to findfoodin the winter. Some animals, such assquirrels, mice and beavers, gather extra food to store in the fall and eat later. Other animals eat different kinds of food as the seasons change. For instance, the red fox eats fruit and insects in the spring, summer and fall. In the winter, they eat small rodentsinstead of fruit and insects, because it is hard to find them.

Certain spiders and insects may stay active if they live in areas without frostand places where theycan find food to eat. Also, some fish stay active in cold water during the winter.

3. Hibernate③

Some animals “hibernate” for part or all of the winter. The animal’s body temperature drops, and its heartbeat and breath slow down, so that it uses very little energy. In the fall, these animals get ready for winter by eating extra food and storing it as body fat. They use this fat for energy while hibernating.

4. Andmore

Cold-blooded animals like fish, frogs, snakes and turtles spend the winter inactive or dormant④ during the winterwhichis similar to hibernation.

Water makes a good shelter for many animals. When the weather gets cold, frogs, turtles and many fish hide under rocks, logs or fallen leaves. Even they bury themselves in the mud, then become dormant. Cold water holds more oxygen than warm water, and the frogs and turtles can breathe by absorbing it through their skin.

Every type of insect has its own way to grow and change and life cycle. That is to say, different insects spend the winter with different ways in different stages of their lives. Many animals spend the winter dormant, or in diapauses⑤. Some insects die after laying eggs in the fall. The eggs hatch into new insects in the spring and everything begins all over again.

① migratev.(候鸟等)定期移栖,(鱼群)回游

② navigatev.航行于,飞行于

③ hibernatev.(动物)过冬,冬眠

④ dormantadj. [生]冬眠的,休眠的

⑤ diapausen. [生]滞育

动物是如何过冬的

天气变冷,白天变短,树叶开始改变颜色,不断凋零。冬天时,白雪覆盖大地。人类会住在暖和的房子中,出去时会穿上厚厚的衣服,食品也可从杂货店中买来。但是动物们会怎么样呢?

1.迁移

动物度过寒冷的冬天的方式真是与众不同、令人惊奇。一些动物采取移居的方法。即迁移到天气会暖和许多或它们可以在那里找到食物的地方。

许多鸟类在秋天便开始迁移,因为这次旅行充满着危险,所以一些鸟类成群结队地旅行。其他的鸟类则是独自飞行。鸟类可以飞行到非常遥远的地方。例如,北极燕欧巢在夏天的时候接近北极点,但到秋天时它将会朝南方一直飞到南极洲。到了春天再回来。

大多数鸟类迁移的距离很短。在鸟类们的大脑中似乎也有一个指南针来用于地球的磁场,像水手们曾经做的一样,使用太阳、月亮、星星来辨别方向,从而完成旅行。

有许多哺乳动物,像一些蝙蝠、北美驯鹿、麋和鲸鱼会在每个冬天旅行去寻找食物。许多的鱼类迁移,它们要么游到南方,要么潜到海水的更深、更暖之处。

昆虫也迁移。一些蝴蝶和蛾子要飞行很远,而大多数迁移类的昆虫则要去近得多的地方。许多动物,象白蚁和日本金龟子会向下深入到土壤的深处。蚯蚓也会向下移动到地表以下大约6英尺的地方。

2.适应

一些动物在冬天保持活跃,但他们必须适应这种变化的天气。许多动物会在行动与身体方面相应的作出一些改变。如为了保持体温,动物们会在秋天生长出新的、厚的多的皮毛。对于狡猾的雪靴兔子来说,新毛皮是白色的,这将帮助他们掩藏在白雪中。

冬天很难找到食物。一些动物,像松鼠、老鼠和海狸,会在秋天积聚足够的食物,储存以备后用。其他的动物也会随着季节的变化而吃不同的食物。如,红狐在春天、夏天和秋天吃水果和昆虫,但在冬天,只能用小的啮齿目动物来代替。

某些蜘蛛和昆虫,如果它们居住在无霜区并能够找到食物,相对来说便会保持活跃状态。类似的还有鱼,它们在冬天也可以在冷水中保持活跃。

3.冬眠

一些动物冬眠来度过部分冬天或者者整个冬天。冬天时候,动物的体温下降,心跳和呼吸减慢,只需消耗非常少的能量。这些动物在秋天的时候就已经通过吃较多额外的食物,将其储存在体内中作为脂肪来为冬天做好了准备。在冬眠时候,他们也就是靠这些脂肪来供给能量。

4.更多

像鱼、青蛙、蛇和乌龟等冷血动物在安静与休眠中度过冬天,因为它们没有办法在冬天保持温度。这和冬眠差不多。

水为许多动物提供了良好的住处。天气变冷,青蛙、乌龟和鱼隐藏在岩石、圆木或者落叶的下面,甚至将自己的身体隐藏在泥浆之中,然后变得静止。冷水比温度高的水可以提供更多的氧气,青蛙和乌龟通过身体来吸收氧气的方式来进行呼吸。

每一种类型的昆虫都有生长和变化的途径,有自己的生命周期。也就是不同的昆虫在不同的生命阶段有不同的方式度过冬天。许多动物在休眠中度过,或者是中止生命。一些昆虫在秋天产蛋以后便会死去。在春天,这些蛋孵化成为新的昆虫,一切便又重新开始。