英语翻译Why don’t birds get lost on their long migratory (迁移的) f

英语翻译
Why don’t birds get lost on their long migratory (迁移的) flights?Scientists tried their best to find the answer to this question for many years.The reasons have been discovered only lately.
Not long ago experiments showed that birds depend on the sun to guide them during daylight .But what about birds that fly mainly by night?tests with man-made stars have proved that certain night-flying birds are able to follow the route in their long distance flights.
One such bird ,a warbler (鸣禽),had spent its lifetime in a cage and had never flown under a natural sky.Yet is showed its ability by birth to use the stars for guidance.The bird's cage was put under a man-made star-filled sky at migration time .The bird tried to fly in the same direction as that taken by other birds in the building.Any change in the position of the make-believe (虚构的) stars caused a change in the direction of its flight.
Scientists think that warblers,when flying in daylight,use the sun for guidance.But stars are clearly their important means of navigation(导航).What do they do when the stars are hidden behind the clouds?Clearly,they find their way by such land marks as mountains,coastlines and river courses.But when it's too dark to see these,the warblers circle helplessly ,unable to find out where they were.

为什么鸟类在它们的迁徙之旅中没有迷路呢?多年来,科学家们试图找到这个问题的答案.
直到目前,这些答案才被发现.不久前,实验显示,在白天,鸟类依靠太阳来当指引.
但是在夜间飞行的鸟类呢?
人造卫星的测试证明,一些夜间飞行的鸟类能在它们的长距离飞行中跟着路线走.
有这样一种鸟,鸣禽.它的整个生命都是在笼中度过的,它从未在自然界的天空飞翔过.
但是,它与生俱来的本领就是使用星辰做向导.
在迁徙期间,在一个人造满天星的天空下放置一个鸟笼.
小鸟会跟着其他鸟类飞行的方向在大楼里飞.
虚构的星星只要转换方向,小鸟的飞行路线也跟着变换方向.
科学家认为,鸣鸟在白天飞行时,它们使用太阳作指引.
但是星星很显然是它们的重要导航.
但是当星星藏在云朵之后,它们又该怎么办呢?
显然,它们会通过一些地面的标志,比如山脉,海岸线和河流来找到它们的路.
但是如果因为太昏暗看不到这些标志,鸣鸟们会无助地盘旋,无法找到它们所在的位置.


（^00^） 希望可以帮到你哦.