英语听力文摘 English Digest 321、鸟儿捕虫的法宝

　　How Do Robins² And Other Birds Find Worms?
鸟儿捕虫的线索
Everyone is familiar with the sight of robins hopping³ around the yard, peering into the grass or “head-cocking” to locate a nice juicy worm. In no time, they find their prey⁴ and fly off with a mouthful.
Cues to find prey
Birds are known to use visual, auditory, and possibly vibrations⁵ or tactile⁶ cues to find prey, but vision is predominant.
The way the robins turn their head when searching for food suggests they could be using visual or auditory cues, but it wasn’t until scientists tested robins in the lab that we really knew for sure how they find worms.
Testing the birds
Birds were placed in aviaries⁷ where they could be given buried mealworms in trays of dirt.
To test if they were using scent⁸ to locate their prey, birds were offered trays with buried live, moving worms and dead ones. Robins found the live worms more often, suggesting they were not using scent.
In the next test, they were given hanging food trays to keep them from touching⁹ the soil with their feet and detecting the worm’s vibrations. The trays did not affect their ability to find the worms, suggesting they do not use tactile cues.
Sound Cues
When cardboard was used as a barrier to block visual cues, the birds could still find the worms. That meant they were using another sense. A last experiment used white noise to block sound cues and the birds had more difficulty finding the worms.
The research concluded that robins could use either visual or auditory cues alone to find worms in the soil, but probably use both. So the next time you see a robin¹ “head-cocking” you can be fairly sure it’s listening and looking for those mouthwatering treats!

　　后院里，知更鸟跳来跳去，注视着草丛，晃头晃脑地搜寻着可口多汁的昆虫。这样的情景相信大家都不陌生。一旦发现“猎物”，它马上叼着虫儿飞走了。
寻找猎物的线索
通常鸟儿们是通过视觉、听觉，有时可能是触觉（昆虫的振动）这些线索来寻找猎物，其中视觉居多。
从知更鸟晃头晃脑地寻找食物可以推断出视觉和听觉线索的利用，但是直到科学家们在实验室中测试，我们才真正明确知更鸟如何发现昆虫。
测试鸟儿
在大型鸟舍中，给鸟儿们提供面粉虫藏在泥里的托盘。
为了测试鸟儿是否通过嗅觉寻找猎物，托盘里分别藏有活着的昆虫和死了的昆虫。知更鸟找出的多是活着的昆虫，这说明知更鸟寻找猎物时并没有利用嗅觉。
下一个测试是：把托盘悬挂起来，这样知更鸟的脚碰不到泥土，也不能探测昆虫的振动。测试并没有影响知更鸟捕捉昆虫，这说明知更鸟寻找猎物时并没有利用触觉。
声音线索
用纸板作为障碍物破坏视觉线索，鸟儿依然能找到昆虫。说明鸟儿是用另种线索。最后的实验利用白色噪音破坏声音线索，鸟儿寻找昆虫困难起来了。
研究结果是知更鸟可以利用视觉或听觉中任一线索寻找泥土中的昆虫，但是也很可能是两种皆有。所以，下次你再看见知更鸟在草丛中摇头晃脑的，你可以确定它们是通过听觉寻找垂涎的美味了！

1 robin   

n.知更鸟，红襟鸟

参考例句：

• The robin is the messenger of spring.知更鸟是报春的使者。
• We knew spring was coming as we had seen a robin.我们看见了一只知更鸟，知道春天要到了。

2 robins   

n.知更鸟，鸫( robin的名词复数 )；（签名者不分先后，以避免受责的）圆形签名抗议书（或请愿书）

参考例句：

• The robins occupied their former nest. 那些知更鸟占了它们的老窝。 来自《现代汉英综合大词典》
• Benjamin Robins then entered the fray with articles and a book. 而后，Benjamin Robins以他的几篇专论和一本书参加争论。 来自辞典例句

3 hopping   

n. 跳跃 动词hop的现在分词形式

参考例句：

• The clubs in town are really hopping. 城里的俱乐部真够热闹的。
• I'm hopping over to Paris for the weekend. 我要去巴黎度周末。

4 prey   

n.被掠食者，牺牲者，掠食；v.捕食，掠夺，折磨

参考例句：

• Stronger animals prey on weaker ones.弱肉强食。
• The lion was hunting for its prey.狮子在寻找猎物。

5 vibrations   

n.摆动( vibration的名词复数 )；震动；感受；（偏离平衡位置的）一次性往复振动

参考例句：

• We could feel the vibrations from the trucks passing outside. 我们可以感到外面卡车经过时的颤动。
• I am drawn to that girl; I get good vibrations from her. 我被那女孩吸引住了，她使我产生良好的感觉。 来自《简明英汉词典》

6 tactile   

adj.触觉的，有触觉的，能触知的

参考例句：

• Norris is an expert in the tactile and the tangible.诺里斯创作最精到之处便是，他描绘的人物使人看得见摸得着。
• Tactile communication uses touch rather than sight or hearing.触觉交流，是用触摸感觉，而不是用看或听来感觉。

7 aviaries   

n.大鸟笼( aviary的名词复数 )；鸟舍；鸟类饲养场；鸟类饲养者

参考例句：

• Alarmed feathers from five aviaries of rare birds went flying. 说来说去，结果都没什么两样。 来自互联网
• Tourists can find some aviaries, some cable cars and Water World there. 在那里游客们可以看到些鸟舍，一些缆车和水世界。 来自互联网

8 scent   

n.气味，香味，香水，线索，嗅觉；v.嗅，发觉

参考例句：

• The air was filled with the scent of lilac.空气中弥漫着丁香花的芬芳。
• The flowers give off a heady scent at night.这些花晚上散发出醉人的芳香。

9 touching   

adj.动人的，使人感伤的

参考例句：

• It was a touching sight.这是一幅动人的景象。
• His letter was touching.他的信很感人。