双语百科：为什么鸟儿在黎明歌唱？ Why do birds sing at dawn?

清晨悦耳的鸟鸣让人心旷神怡，但是一天中的其他时间却很少能听到鸟叫。为什么鸟儿都喜欢在清晨歌唱？来本文中寻找答案吧。

Wake up early enough and, depending on where you live, you’ll likely hear a pleasant chorus of birds chirping their tiny hearts out. This am avian arrangement is instinctual behavior for birds, but why?
早上起得够早的话，在你所住的地方也许能听到一阵悦耳的鸟鸣。在清晨歌唱是鸟的本能行为，但是鸟鸣为什么都在清晨呢？

According to the Woodland Trust, this early singing is known as the dawn chorus, and it can start as early as 4 am and last for several hours. Birds do it to attract mates and warn other birds to avoid their turf. One theory as to why they opt for the wee hours to communicate these important messages is because the low visibility makes it hard to do other bird activities, like foraging. Keeping their activity level low, they opt to sing instead.
林地信托机构称，鸟儿在清晨鸣叫最早从凌晨4点开始，可持续数个小时。鸟鸣叫是为了吸引配偶，也是为了警告其他鸟不要入侵自己的领地。关于鸟类为什么选择在凌晨传递这些重要信息，有一个理论是，凌晨能见度低，鸟类难以进行觅食等其他活动，既然无事可做，那么鸟儿就转而选择鸣叫。

Another theory argues that birds use the morning vocals to project an image of strength. By singing with fervor, they’re letting other birds know they survived the night—no guarantee in nature—and would make for an excellent mate.
另一种理论认为，鸟类利用晨鸣来展示自己的力量。通过热情地歌唱，它们让其他鸟儿知道自己已经安然度过黑夜——要知道自然界的动物过着朝不保夕的日子，不一定能看见明天的太阳——并能够成为出色的伴侣。

Like a good recording studio, the early morning hours also allow birds to transmit a clear tune thanks to the cooler, drier air. Because birds have distinctive chirps, that clarity helps them be more easily identified by birds within listening distance.
清晨的空气更凉爽、更干燥，就像一个效果很好的录音棚，鸟儿在此时歌唱能传递出清晰的音质。因为鸟儿的声音各有不同，这种清晰度可以让听得见的鸟儿更容易识别出它们的声音。

There used to be a prevailing theory that birds sang so much in the mornings because the sounds could travel greater distances due to less atmospheric turbulence, but it was disproven by researchers at the University of Western Ontario in 2003. They played recordings of sparrows at dawn and midday. The songs didn’t travel farther, but they were more consistent.
过去有一个流行的理论认为，鸟儿最爱在清晨鸣叫是因为在气流稳定的时候声音能传播得更远。但是西安大略大学的研究人员在2003年否定了这一理论。研究人员在黎明和中午分别播放了麻雀的录音。然而麻雀声音并没有传播得更远，只不过黎明时分麻雀的叫声更连贯。

Because birds only have so much energy to belt one out, singing when they stand the best chance of being heard makes sense. For a bird, an early morning session is like having the perfect acoustic environment for their performance.
因为鸟儿只能用有限的精力来鸣叫，它们自然会选择在最可能被听到的时候歌唱。对一只鸟儿来说，清晨鸣叫相当于在最佳音效环境中表演。

英文来源：Mental Floss

编译：丹妮

审校：董静、齐磊