Scientists believe that a majority of the earth's bird population migrate in some fashion or other.

科学家认为，地球上大多数鸟类以某种方式迁徙。

Some travel seasonally for relatively short distances, such as birds that move from their winter habitats in lowlands to mountain tops for the summers.

有些鸟类进行季节性地迁徙，飞行距离较短，比如有的鸟类夏季要从冬季栖息的低地迁徙到山顶。

Others, like the Arctic Tern, travel more than 25,000 miles seasonally between the northern and southern poles.

其他鸟类，如北极燕鸥，季节性地在北极和南极之间迁徙超过25000英里。

Bird migration has been studied over many centuries through a variety of observations.

几个世纪以来，人们通过各种各样的观察对鸟类迁徙进行了研究。

But until relatively recently, where birds went to in the winter was considered something of a mystery.

但直到最近，鸟类在冬天去哪里才被认为是一个谜。

The lack of modern science and technology led to many theories that we now recognize as error-filled and even somewhat amusing.

现代科学技术的缺乏导致了许多我们现在认为充满错误甚至有些可笑的理论的产生。

Take hibernation theory for example – two thousand years ago, it was commonly believed that when birds left an area, they went underwater to hibernate in the seas and oceans.

以冬眠理论为例。两千年前，人们普遍认为当鸟类离开某个地区时，它们会潜入水下，在海洋中冬眠。

Another theory for the regular appearance and disappearance of birds was that they spent winter hidden in mud till the weather changed and food became abundant again.

关于鸟类定期出现和消失的另一种理论是，它们躲在泥里过冬，直到天气变化，食物再次丰富起来才出来。

The theory that some birds hibernate persisted until experiments were done on caged birds in the 1940s which demonstrated that birds have no hibernation instinct.

一些鸟类冬眠的理论一直存在，直到20世纪40年代科学家用笼中鸟进行了实验，证明鸟类没有冬眠本能。

One of the earliest naturalists and philosophers from ancient Greece was Aristotle who was the first writer to discuss the disappearance and reappearance of some bird species at certain times of year.

亚里士多德是古希腊最早的自然主义者和哲学家之一，他是第一位在书中讨论某些鸟类在一年中特定时间消失和再现的人。

He developed the theory of transmutation, the seasonal change of one species into another, by observing redstarts and robins.

他通过观察红尾鸲和知更鸟，发展了嬗变理论，即一个物种向另一个物种的季节变化。

He observed that in the autumn, small birds called 'redstarts' began to lose their feathers, which convinced Aristotle that they changed into robins for the winter, and back into redstarts in the summer.

他观察到，在秋天，被称为“红尾鸲”的小鸟开始失去羽毛，这让亚里士多德相信，它们在冬天变成了知更鸟，在夏天又变成了红尾鸲。

These assumptions are understandable given that this pair of species are similar in shape, but are a classic example of an incorrect interpretation based on correct observations.

鉴于这两种鸟体型相似，这些假设是可以理解的。但这是基于正确观察的错误解释的典型例子。

The most bizarre theory was put forward by an English amateur scientist, Charles Morton, in the seventeenth century.

最奇怪的理论是由英国业余科学家查尔斯·莫顿在17世纪提出的。

He wrote a surprisingly well-regarded paper claiming that birds migrate to the moon and back every year.

他写了一篇广受好评的论文，声称鸟类每年都会迁徙到月球上。

He came to this conclusion as the only logical explanation for the total disappearance of some species.

他得出这个结论是对某些物种完全消失的唯一合乎逻辑的解释。

One of the key moments in the development of migration theory came in 1822 when a white stork was shot in Germany.

移民理论发展的关键时刻之一是在1822年，当时一只白鹳在德国被射杀。

This particular stork made history because of the long spear in its neck which incredibly had not killed it – everyone immediately realised this spear was definitely not European.

这只鹳之所以创造了历史，是因为插在它脖子上却没有将它杀死的那支长矛。每个人都立刻意识到这把矛绝对不是来自欧洲。

It turned out to be a spear from a tribe in Central Africa.

事实证明那是一支来自中非一个部落的长矛。

This was a truly defining moment in the history of ornithology because it was the first evidence that storks spend their winters in sub-Saharan Africa.

这是鸟类学史上一个真正的决定性时刻，因为这是鹳类在撒哈拉以南非洲过冬的第一个证据。

You can still see the 'arrow stork' in the Zoological Collection of the University of Rostock in Germany.

你仍然可以在德国罗斯托克大学的动物收藏中看到“箭矢鹳”的标本。

People gradually became aware that European birds moved south in autumn and north in summer but didn't know much about it until the practice of catching birds and putting rings on their legs became established.

人们逐渐意识到，欧洲鸟类在秋天向南迁徙，在夏天向北迁徙。但直到人们捕捉鸟类并在其腿上戴上铁环之前，人们对这一点知之甚少。

Before this, very little information was available about the actual destinations of particular species and how they travelled there.

在此之前，关于特定物种的实际目的地以及它们如何前往那里的信息非常少。

People speculated that larger birds provided a kind of taxi service for smaller birds by carrying them on their backs.

人们推测，体型较大的鸟类为体型较小的鸟类提供了一种类似出租车的搭乘服务，它们把体型较小的鸟类背在背上。

This idea came about because it seemed impossible that small birds weighing only a few grams could fly over vast oceans.

这个想法的产生是因为体重只有几克的小鸟似乎不可能飞越辽阔的海洋。

This idea was supported by observations of bird behavior such as the harassment of larger birds by smaller birds.

对于鸟类行为的观察证明了这一点，比如小型鸟类对大型鸟类的骚扰行为。

The development of bird ringing, by a Danish schoolteacher, Hans Christian Cornelius Mortensen, made many discoveries possible.

丹麦教师汉斯·克里斯蒂安·科内利厄斯·莫滕森发明了鸟环，使许多发现成为可能。

This is still common practice today and relies upon what is known as 'recovery' – this is when ringed birds are found dead in the place they have migrated to, and identified.

直到现在，这仍然是一种常见的做法，并依赖于所谓的“寻回”，即在在鸟类迁徙的地方发现并且识别出带了鸟环的鸟。

Huge amounts of data were gathered in the early part of the twentieth century and for the first time in history people understood where birds actually went to in winter.

在二十世纪早期，人们收集了大量的数据，这在历史上是第一次了解鸟类在冬天究竟去了哪里。

In 1931, an atlas was published showing where the most common species of European birds migrated to. 1931

年，一本地图册出版，显示了欧洲最常见的鸟类迁徙到什么地方。

More recent theories about bird migration …

关于鸟类迁徙的最新理论……