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It may not be the most melodious¹ bit of birdsong you’ll ever encounter. [Titmouse alarm call]. But this particular call, issued by a tufted titmouse, conveys important information about the presence of potential predators². But only if other birds can hear it.  

它可能不是你听过的最悦耳的鸟鸣声[山雀的警报信号]。但这由簇山雀发出的特殊的呼叫，传达出重要的信息——存在潜在的捕食者。但只有其他鸟类才能听到。

Unfortunately, near a highway, traffic sounds can drown out such alarm calls. Scientists have long observed a decrease in wildlife populations in habitats adjacent to major roadways. And many figured it was the noise that drives creatures to hightail it someplace more remote. But it could be more than mere³ annoyance⁴ that keeps animals away. The inability to hear potentially life-saving calls could also be a factor. That’s according to a study in the journal Biology Letters. [Aaron M. Grade and Kathryn E. Sieving⁵, When the birds go unheard: highway noise disrupts information transfer between bird species]

不幸的是，在高速公路附近，交通的声音可以淹没这样的警报信号。科学家们观察到栖息地靠近主干道的野生动物种群数量在减少。并且许多人认为正是噪音驱赶动物们逃离到更偏远的地方。但也可能只是纯粹的打扰使得动物远离。《生物学快报》杂志上的一项研究结果表明，无法听到潜在的救命信号也可能是其中因素之一。

To test that theory, Aaron Grade and Kathryn Sieving at the University of Florida recorded that titmouse alarm call, made by a captive individual that had spotted⁶ an owl⁷. They then played this alarm call from speakers mounted in different locations in Florida state parks. Some of the spots were noisy, along Interstate 75 or U.S. Route 441. Others were more secluded⁸ and relatively⁹ quiet.

为了检验这一理论，Aaron Grade和Kathryn Sieving 在佛罗里达大学对一只圈养的山雀发出的警报信号进行录音，当发现猫头鹰时。然后他们在佛罗里达州国家公园不同的地点通过安装的扬声器来播放这一警报信号。75号州际公路或美国441号公路旁的一些地点噪音很大。其他地点则更加隐蔽，并且相对安静。

The scientists then observed the reactions of cardinals¹⁰ to these broadcasted declarations of danger. Because cardinals and other birds often eavesdrop¹¹ on the talk of titmice for news of impending¹² peril¹³.

然后科学家观察红雀对所播放危险信号的反应，因为红雀和其他鸟类经常窃听山雀发布紧急危险信息的谈话。

In the quiet areas, cardinals clearly responded to the titmouse alarms. They froze in place, stopped singing and scanned the area for predators. But in the noisy places, cardinals paid the warnings no heed¹⁴ and continued their regular activities.

在安静的地方，红雀明确回应了山雀的警报。它们僵在原地，停止歌唱并扫描捕食者。但在嘈杂的地方，红雀对警报置若罔闻，并继续进行常规的活动。

It’s not completely clear whether the cardinals could not hear the calls or if they were simply too distracted by the traffic to respond. Either way, looks like some birds should seek the road less traveled—or travel the regions less road-ed. Whereas hungry owls¹⁵ should hit the highway if they’re looking to sneak¹⁶ up on a snack.

对于红雀是否听不到警报或者它们仅仅是由于被交通打扰分心而做出回应，这一点还没有完全弄清楚。无论是哪种，看起来有些鸟应该寻求人迹罕至的道路——或者在有更少道路的地区飞行。而饥饿的猫头鹰如果想偷偷的靠近一个“点心”，应该到高速公路附近。