如果你是一只食肉鸟，你怎样能俯视连绵的草地或者沙漠，试图辨认出只有几英寸长的猎物。


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选材／校对／翻译：hqj5715
When you're away from home and it's time to eat, how do you know where to go to find food? Well, you probably just look for big, glowing fast food signs. But, what if you're a bird of prey, looking down on miles of grassland or desert, trying to spot a meal that's only a few inches long? While birds of prey do have unbelievably keen eyesight, that isn't always enough. They still have to know where to look, especially when they're scanning miles of unfamiliar territory, and the meal they're looking for is a tiny mouse. How Do Birds Do It? By using chemical fast food signs to help them zoom in on the best places to find their prey. Most birds that hunt in the daytime have eyes that are sensitive to ultraviolet light, in addition to the visible light that humans can see. Their most common prey are small rodents such as mice. These rodents mark their territories using urine and waste. Under ultraviolet light, most of these scent markings glow with a blue light. The main trails in each colony are “marked” over and over again by every passing user, so the glow from these high-traffic areas can get pretty bright.
当你不在家而且正是吃饭的时候，你怎样知道到哪里去找食物？ 你也许正巧找到一个大的，亮着的快餐广告牌。但是，如果你是一只食肉鸟，你怎样能俯视连绵的草地或者沙漠，试图辨认出只有几英寸长的猎物。 虽然食肉鸟确实具有难以置信的，敏锐视觉，但是这往往并不足够。他们仍必须知道去哪里找，尤其当他们审视较大距离并不熟悉的领域而且他们正在寻找的猎物是很小的老鼠时。 食肉鸟是怎样做到的呢？ 通过利用猎物的化学记号帮助他们放大可以找到猎物的最有利地方。 大多数白天进行涉猎的食肉鸟的眼睛除了能够看见人类可以看到的可见光外还对紫外线敏感。他们最平常的猎物是像老鼠这样小的啮齿类动物。这些啮齿动物食用尿液和粪便标记他们的领地。在紫外线下，大部分这些具有气味的标记物发出蓝色的光。 每一块领地的主要干道被通过的啮齿动物一次又一次的标记，因此从这些交通要道发出的光线非常的明亮。