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Staring Eyes and Swiveling Necks
瞪大眼睛和旋转脖子
Ask any gradeschooler to imitate an owl and you'll probably get one of two responses: the giant, staring eyes or that amazingly swivel-prone neck. As it turns out, these two characteristic features are related; they are part of an overall system owls have for catching prey.
让任何小学生模仿猫头鹰，他们大概都会有这两种反应：瞪大眼镜，拼命地旋转脖子。事实证明，这两种动作是有联系的；都是猫头鹰完整捕猎系统中一部分。
To understand the connection, remember that owls are nocturnal birds: they hunt for food at twilight and even in the dark. Food for an owl may be something as large as a rabbit or as small and hard to see as a field mouse. Not only is this kind of meal difficult to spot, it also has a tendency to bolt away quickly at the slightest sound.
要弄懂这种联系，须知道猫头鹰是夜行动物。他们在黄昏甚至是黑夜里寻找食物。猫头鹰有时捕食像兔子一样大的猎物，有时捕食如地鼠一般又小又难看见的猎物。这些猎物不仅很难被发现，而且听到一点风吹草动就会迅速消失得无影无踪。
The owl overcomes these difficulties by having evolved a visual system that works even at great distances and in low light. This is partly the result of having large eyes that are set on a relatively flat face, thus increasing binocular vision. However, those big eyes don't move much in their sockets, and the owl's total visual field is therefore reduced. At any given time, it only sees about one third as much as birds with eyes on either side of their heads.
猫头鹰视觉系统不断进化，使它在很远或者很黑的情况下看清物体，这样就克服了那些困难。由于猫头鹰面部相对扁平，再嵌上一双大眼睛，这样就增强了双眼视力。然而大眼睛不易在眼窝里转动，因此猫头鹰的整个视野范围受到限制。它的视野只有其它眼睛长在头两边的鸟类的三分之一。
That means the only thing to do is to be able to turn those staring eyes in any direction, without the noise that would be caused by actually getting up and moving. And now you can see how the staring eyes and swiveling neck work together: the owl's super-flexible spine allows it to remain silent while it scans 180 degrees on either side. Yes indeed -- from a forward-facing position, an owl can look entirely backwards.
这意味着猫头鹰唯一能做的就是，将瞪大的眼睛转向各个方向，并避免因跳上跳下，来回走动而发出声响。现在你明白瞪大的眼镜和旋转的脖子是怎样合作的：猫头鹰的脊梁超级灵活，可以两边180度角地快速侦查环境而不发出任何声响。虽然眼睛长在前方，但猫头鹰确实可以看清后面。
