44 L5-Greate Migrations

Oxford Read and Discover level 5 Great Migrations by Rachel Bladon

牛津阅读和发现第5级大迁徙由雷切尔·布莱登

Introduction Around the world, day and night, and in every season, animals are moving from one place to another. They move over land, in the air, or through water. Some make short journeys, others go across the world. These animals are all migrating. Animal migrations are amazing. What animals can you see below? Why do animals migrate? How do animals find their way when they migrate? What animal has made the longest migration? What animals migrate to or from your country? Discover! Now read and discover more about some great animal migrations!

在世界各地，动物不分昼夜，不分季节，都在从一个地方迁移到另一个地方。 它们在陆地上、空中或水中移动。 有些人做短途旅行，有些人环游世界。 这些动物都在迁徙。 动物的迁徙是惊人的。 你能在下面看到什么动物? 为什么动物会迁徙?动物在迁徙时是如何找到路的? 什么动物迁徙的时间最长? 你的国家有什么动物迁徙? 发现!现在阅读和发现更多关于一些伟大的动物迁徙!

Chapter 1 On the Move Migration is when animals move from one place to another. Sometimes huge numbers of animals migrate together, but some animals migrate thousands of kilometers all alone. Why Do Animals Migrate? Many places are not good for animals to live in all year long. The places are sometimes too cold or hot, or not good for baby animals. Sometimes there is not enough food. Animals have to move away for part of the year or for part of their lives. They migrate to find food, water, and a safe place to live or breed. Sometimes all the animals in a species migrate. This is called complete migration. If only some animals in a species migrate, it's called partial migration. Discover! Arctic terns migrate from the Arctic to the Antarctic and back every year. That's almost 50,000 kilometers! When To Go Animals that migrate are called migrants. Many migrants leave their home at the same time every year. They reach the end of their journey at about the same time, too. So how do they know when it is time to leave? Animals see things in the world around them that tell them to leave. The days get longer or shorter. The weather gets hotter or colder, or there is less food to eat. Scientists think that when migrants see that these things are changing, their bodies make special chemicals called hormones. The hormones make an animal eat lots of food so that it has enough energy for its journey.

迁徙是指动物从一个地方迁移到另一个地方。 有时大量的动物一起迁徙，但有些动物独自迁徙数千公里。 动物为什么迁徙?许多地方不适合动物全年生活。 这些地方有时太冷或太热，或者对小动物不好。 有时没有足够的食物。 动物不得不在一年中的一部分时间或生命的一部分时间里离开。 它们迁徙是为了寻找食物、水和一个安全的地方生活或繁殖。 有时一个物种中的所有动物都会迁徙。 这被称为完全迁移。 如果一个物种中只有一些动物迁移，这被称为部分迁移。 发现!北极燕鸥每年都要从北极飞到南极再飞回来。 差不多是5万公里!何时迁徙迁徙的动物被称为迁徙者。 每年的同一时间，许多移民离开他们的家。 它们也几乎同时到达旅程的终点。 那么他们怎么知道什么时候该离开呢? 动物看到它们周围的世界告诉它们离开。 白天变长或变短。 天气变热或变冷，或者食物变少。 科学家们认为，当移民们看到这些变化时，他们的身体会产生一种叫做激素的特殊化学物质。 荷尔蒙使动物吃很多食物，这样它就有足够的能量来完成它的旅程。

Finding Their Way Animals are very good at finding their way. Some use landmarks— important places that they can see, for example, mountains and coasts. Others use the sun during the day, or the moon and stars at night. Some animals use smells to help them to find their way. Scientists think that some animals can even feel Earth's magnetic field and use it to tell them where they are. It's like the animals have a compass inside. Discover! Some animals, like bats and whales, make special sounds when they are moving. The echoes from these sounds help them to find their way. Dangers Migrating is often dangerous. The journey is very tiring for animals, and they sometimes find it difficult to get food and water. They are in danger from bad weather and predators— other animals that want to kill and eat them. There are many dangers, but these do not stop migrants. They have to make long journeys to find safe places to breed and a home with lots of food!

动物很擅长找路。 有些人使用地标——他们能看到的重要地方，例如山脉和海岸。 有些人白天利用太阳，晚上利用月亮和星星。 有些动物用气味来帮助它们找到路。 科学家们认为一些动物甚至可以感觉到地球的磁场，并利用它来告诉它们自己在哪里。 就像动物体内有一个指南针。 发现!有些动物，如蝙蝠和鲸鱼，在移动时会发出特殊的声音。 这些声音的回声帮助它们找到路。 迁徙往往是危险的。 这段旅程对动物来说很累，它们有时很难得到食物和水。 它们面临着恶劣天气和捕食者——其他想要杀死并吃掉它们的动物的危险。 有很多危险，但这些并不能阻止移民。 它们必须长途跋涉才能找到安全的地方繁殖，找到一个有很多食物的家!

Chapter 2 Bird Migrations There are many different species of bird, and about half of them migrate. Some birds only travel a few kilometers, but others go all the way around the world! Where Do Birds Migrate? In the northern half of the world, days are long in summer, and birds can easily find food for their young. In winter, many of these birds fly south because it's too cold in the north and there is not enough food. Birds in the southern half of the world fly north for winter and back south for summer. Many birds also migrate between east and west, usually looking for warmer winter weather near the ocean. Most birds in the Tropics do not migrate because it's always warm there. Discover! Bar-tailed godwits from New Zealand fly further without stopping than any other bird. They fly 11,500 kilometers to China. Then after feeding, they fly another 5,000 kilometers to Alaska to breed! Getting Ready Before birds migrate, they need to eat a lot of food so that they have enough energy for their journey. Some birds double their weight before migrating. Their muscles become stronger, too. Before migrating, many birds also molt they lose their old feathers and new ones grow. They wait for good weather, and then they are ready to go!

鸟类的迁徙有许多不同的种类，其中约有一半会迁徙。 有些鸟只飞几公里，但有些鸟却能环游世界!鸟类迁徙到哪里? 在北半球，夏天白天很长，鸟类很容易为幼鸟找到食物。 在冬天，许多这些鸟飞到南方，因为北方太冷了，没有足够的食物。 南半球的鸟类冬天向北飞，夏天又飞回南方。 许多鸟类也在东方和西方之间迁徙，通常是在海洋附近寻找温暖的冬天。 热带地区的大多数鸟类都不迁徙，因为那里总是很温暖。 发现!新西兰的斑尾鹬比其他任何鸟类都飞得更远。 他们飞了11500公里到中国。 然后在进食后，它们再飞5000公里到阿拉斯加繁殖!在鸟类迁徙之前，它们需要吃很多食物，这样它们才有足够的能量进行迁徙。 有些鸟在迁徙前体重会增加一倍。 他们的肌肉也变得更强壮。 在迁徙之前，许多鸟类也会蜕皮——它们会掉掉旧的羽毛，长出新的羽毛。 他们等待好天气，然后就准备出发!