This is Scientific American — 60-Second Science. I'm Christopher Intagliata.
You may have spotted V-shaped squadrons of geese heading south this fall. But for many migrants—like smaller songbirds—nighttime is the right time, when it comes to migration. Winds are gentler. And darkness helps them avoid airborne attacks. Of course darkness also makes it harder for us to see them. Which is where weather radar comes in.
"These radars were designed to detect water drops in the air, precipitation in the air." Jeff Buler, an ornithologist and aeroecologist at the University of Delaware. "They also detect any other large object that will reflect back radio energy. It essentially sees insects and bats and birds as large drops of water."
Buler and his team used three weather surveillance radars to track migratory birds near the Great Lakes—observing four spring migrations in a row. And what they found was, as the night migration ended, and dawn broke, many birds in flight over the lakes turned back. Decided to quit for the day. Which meant crowded real estate on the south shore of the lakes, as the birds piled up there to wait out the day. The study is in the journal The Auk.
The message for conservators? "Restoring one hectare of forest along the shoreline of Lake Michigan might be able to support more migrants than a hectare of forest 50 km away from the shoreline." Because birds—just like humans—like that lakefront property.
Thanks for listening for Scientific American — 60-Second Science Science. I'm Christopher Intagliata.
大家可能注意到了在今年冬天摆成V形队飞往南方的鸿雁 。但是，对于小型鸣禽等众多迁徙动物而言，夜晚才是适合迁徙的时间 。夜晚的风更加柔和 。而且黑暗可以帮助它们避免空降袭击 。当然，黑暗也使我们更难看到它们 。这正是引用气象雷达的原因所在 。
“这些雷达用来检测空气中的水滴和空气悬浮物 。”杰夫·布勒是特拉华大学的鸟类学家和航空生态学家 。“这些雷达还能检测可以反射无线能量的其他大型物体 。从本质上来说，它把昆虫、蝙蝠和鸟类视为大的水滴 。”
布勒和他的团队用三个气象监视雷达追踪五大湖附近的候鸟，他们连续观察了四个春季迁徙 。他们发现，晚上迁徙结束后，临近破晓时分，许多在湖泊上空飞翔的鸟儿会掉头飞回来 。它们决定白天停止飞行 。这意味着湖区南岸的房地产很紧张，因为这些鸟儿白天会聚集在这里等待夜晚的来临 。这项研究结果发表在《海雀》期刊上 。
这向环境保护者传达了什么信息？“恢复密歇根湖沿湖岸上1公顷的森林可能会保护更多的迁徙鸟类，而不仅仅是保护距离沿湖岸50英里远的1公顷森林 。”因为鸟类和人类一样，它们也喜欢湖畔房产 。
谢谢大家收听科学美国人——60秒科学 。我是克里斯托弗·因塔利亚塔 。
1. when it comes to 谈到；涉及；
例句：I'm a real coward when it comes to going to the dentist.
2. see as 认为；把…看作；
例句：Only those with a strategic perspective are likely to see this as the great opportunity it represents.
3. in a row 连续地；接连不断地；不间断地；
例句：They dropped two games in a row and were eliminated from the tournament.
4. pile up （使）堆放；（使）堆积；（使）成堆；
例句：The autumn leaves fall and pile up.