(单词翻译:单击)
听力文本
This is Scientific American — 60-Second Science. I'm Karen Hopkin.
Got a minute?
It may not be the most melodious 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 predators. But only if other birds can hear it.
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 mere annoyance 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.
To test that theory, Aaron Grade and Kathryn Sieving at the University of Florida recorded that titmouse alarm call, produced by a captive individual that had spotted an owl. 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 secluded and relatively quiet.
The scientists then observed the reactions of cardinals to these broadcasted declarations of danger. Because cardinals and other birds often eavesdrop on the talk of titmice for news of impending peril.
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 heed and continued their regular activities.
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 owls should hit the highway if they're looking to sneak up on an unexpecting snack.
Thanks for listening Scientific American — 60-Second Science Science. I'm Karen Hopkin.
参考译文
这里是科学美国人——60秒科学。我是凯伦·霍普金。
有一分钟时间吗？
（山雀的警报信号）可能不是你听过的最悦耳的鸟鸣声。但是这种由簇山雀发出的特殊呼叫，传递了重要的信息——可能存在捕食者。但前提是其他鸟类得能听到这一警报。
不幸的是，在高速公路附近，交通声音会淹没这种警报信号。经过长期观察，科学家发现栖息地靠近主干道的野生动物种群数量在减少。许多人认为正是这种噪音迫使动物们逃到了更偏远的地方。但使动物远离的可能不仅仅是打扰这一个因素。无法听到潜在的救命信号也可能是因素之一。这一研究结果刊登在《生物学快报》杂志上。
为了验证这一理论，佛罗里达大学的亚伦·格雷德和凯瑟琳·西温录下了簇山雀的警报信号，这是在它发现猫头鹰的时候发出的。然后他们用设置在佛罗里达州立公园不同地方的扬声器播放这一警报信号。75号州际公路和441号美国国道沿线的一些地点噪音很大。而其他地方则更加隐蔽且相对安静。
然后科学家观察了红雀对所播放危险信号的反应。因为红雀和其他鸟类为了得到即将到来危险的消息，经常偷听山雀的对话。
在安静的地方，红雀对山雀的警报信号做出了清晰的反应。它们僵在原地，停止歌唱，仔细查看周围的区域是否有捕食者出现。但是在吵闹的地区，红雀没有理会这种警报，继续正常活动。
目前并不完全清楚红雀是没有听到警报，还是仅仅是因交通而分心所以没有做出回应。无论怎样，看起来有些鸟类应该寻找旅客少的路段或者寻找公路少的区域生存。反之，饥饿的猫头鹰如果想偷偷靠近一个“点心”，应该到公路附近寻找觅食机会。
谢谢大家收听科学美国人——60秒科学。我是我是凯伦·霍普金。
译文为可可英语翻译，未经授权请勿转载！
重点讲解
重点讲解：
1. drown out 盖过，淹没(声音)；
例句：Her voice was drowned out by a loud crash.
她的声音被一声响亮的撞击声所淹没。
2. eavesdrop on 偷听；窃听；
例句：It is not polite to eavesdrop on the conversation of other people.
偷听他人说话是很不礼貌的。
3. respond to 应对；作出回应；作出反应；
例句：The horse responds to the slightest pull on the rein.
只要缰绳稍稍一拉，这匹马就有反应。
4. either way (两种情况中)不论发生哪一种情况；
例句：Was it his fault or not? Either way, an explanation is due.
是他的错不是?无论是不是，都得有个解释。
5. sneak up on 偷偷地走近；偷偷地挨近；
例句：I managed to sneak up on him when you knocked on the door.
你敲门的时候，我设法悄悄靠近了他。
