Elephants Can Mimic Traffic Noises, Study Says
汽车爱卡网 科学家日前表示，并不是只有小孩子在摆弄玩具汽车时会模仿引擎发动的声音，他们发现大象也能发出类似的叫声，只不过这种声音更像非洲高速公路上来往卡车发出的隆隆声。
It isn"t only children playing with toy cars who make engine noises. Elephants produce a similar roar, though in their case it"s the rumble of trucks on an African highway that the animals imitate, scientists say.
据美国《国家地理》杂志网站3月23日报道，进行这项研究的科学家表示，与鹦鹉、某些鸣禽、海豚和人类一样，大象具有模仿声音的能力。动物学家乔伊斯・普尔是安博塞利大象研究计划的负责人，也是第一个注意到这种现象的人。她在肯尼亚安博塞利国家公园(Amboseli National Park)里，发现了一半野生的、孤儿大象的象发出了不同寻常的奇怪叫声。普尔曾试图通过声音来追踪一只名为米爱卡的雌性大象，但是这只10岁大象出的模仿能力让普尔的任务变得并不简单。普尔说：“有些时候，我简直分不清究竟是远方的卡车发出的声音还是米爱卡的叫声，这让我非常好奇，我想是不是米爱卡能够模仿卡车行驶的声音呢?”
普尔还表示，米爱卡这个象中的其它成员也被人们发现能够发出类似的声音，而这种声音和以前曾记录在案的任何一种大象的叫声都明显不同。普尔猜测，米爱卡是在繁忙的内罗毕至蒙巴萨高速公路附近，模仿卡车发出的声音的。米爱卡的围栏距内罗毕至蒙巴萨的高速公路间大约有2英里(3公里)的路程，为了打发无聊的夜晚，米爱卡开始模仿远处公路上隆隆的车声。
对于大象为何会模仿汽车的声音，还有另外一个可能的解释，即米爱卡模仿这种声音可能单单是因为它喜欢卡车发出的这种隆隆声。对此，普尔解释说：“或许，这种声音能让米爱卡感到愉快，就像我们听到嗡嗡声会觉得舒服一样。”她还同时指出，无论大象模仿这种声音的`动机是什么，最主要的一点是，大象确实能够发出这种声音。“这说明它们能发出不同寻常的新奇的声音，这些声音是它们通过模仿其它动物或是机器学来的。而这种行为在哺乳动物中极其少见。”
普尔的发现作为一项研究的中心内容被发表在本周的科学期刊《自然》上。普尔和这篇文章的合著者认为，大象这种居生活的动物通过模仿声音，来帮助各自之间保持联系。文章中还提到了一只名叫卡利莫罗的23岁雄性非洲象。卡利莫罗生命中有18年的时间是和瑞
士巴塞尔动物园的亚洲象生活在一起的。与非洲象不同，亚洲象通常是发出“喳喳”的声音来彼此联系的。卡利莫罗学会模仿这种声音后，它几乎拒绝再接受任何其它的声音。
研究者表示，这是人们首次发现非灵长类的陆地哺乳动物具有模仿，学习声音的能力。在野生环境中，大象经常要在距离很远的时候，彼此进行沟通和交流，这时它们会使用低频叫声和同一象中的其它成员保持联系。有试验证实，大象可以在1.5英里(2.5公里)的距离之外，分辩出象中特殊个体的叫声。所以，具备一种独一无二的可识别的叫声无疑是非常有用的，就像米爱卡发出的这种低沉的，卡车一样的隆隆声一样。
普尔表示，这种与众不同的叫声好像是一种声音信号，这种信号是针对这只大象的亲人或者和它关系非常紧密的其它大象发出的。她说：“在关系复杂又呈流动性的象中，声音的模仿可能是被用来进行维持个体和特殊动物体间的关系的。”
It isn"t only children playing with toy cars who make engine noises. Elephants produce a similar roar, though in their case it"s the rumble of trucks on an African highway that the animals imitate, scientists say.
The experts behind the discovery say elephants are capable of vocal imitation, joining a select group of animals that includes parrots, songbirds, dolphins, and humans.
Zoologist Joyce Poole was the first to notice some rather unelephantine noises emanating from a group of semiwild, orphaned elephants in Tsavo National Park, Kenya. She managed to track the sounds to a female named Mlaika. But the ten-year-old"s powers of mimicry were so developed that the task wasn"t easy.
"I was sometimes unable to distinguish between the distant trucks and Mlaika"s calling," said Poole, the scientific director of the Amboseli Elephant Research Project. "This is what first made me wonder whether she could possibly be imitating the truck sounds."
Poole said others in Mlaika"s group have been heard to make a similar noise, which is quite different from any call previously recorded in elephants.
Poole suspects Mlaika began mimicking traffic on the busy Nairobi-Mombassa highway because she got bored in her nighttime stockade located two miles (three kilometers) awa
y from the road. "It was a sound she heard every night. Just after sunset sound travels well on the savanna."
Another possible explanation is that Mlaika might simply like the rumble of trucks. "Perhaps it was pleasing to her in some way, like humming is to us," Poole speculated.
Whatever the motivation, the main point, Poole said, is that elephants can actually produce such a sound.
"It shows they are able to come up with novel sounds outside their normal repertoire―some of which they have learned through imitating other animals or machines," Poole said. "This is extremely unusual for mammals."
Poole"s findings are central to a study published this week in the science journal Nature. Poole and her co-authors suggest elephants use vocal learning to help the group-living animals stay in touch.
The study also refers to a 23-year-old male African elephant named Calimero, which spe
nt 18 years living with Asian elephants at the Basel Zoo in Switzerland. Unlike their African counterparts, Asian elephants usually communicate using chirping sounds. Calimero has learned to imitate these calls, using them almost to the point of excluding all other sounds.
"Vocal learning enables a flexible and open communication system in which animals may learn to imitate signals that are not typical of the species," the researchers wrote.
They say this is the first time vocal learning has been recorded in a nonprimate land mammal.
In the wild, elephants often need to communicate over long distances, using low frequency calls to keep tabs on other members of their group. Experiments have shown that elephants can recognize the voices of particular individuals at distances of up to one and a half miles (two and a half kilometers). So having a uniquely recognizable call, like Mlaika"s low truck-rumble sound, could be a very useful.
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