很久以前，在夏威夷大島上聽(tīng)到烏鴉叫是司空見(jiàn)慣的事：（野生夏威夷烏鴉的叫聲）那是夏威夷烏鴉的呼聲。今天出國(guó)留學(xué)網(wǎng)小編就給大家介紹一下托福聽(tīng)力科學(xué)美國(guó)人60秒 夏威夷烏鴉的叫聲。
This is Scientific American — 60-Second Science. I＇m Jason Goldman.
Got a minute？
Once upon a time， on the big island of Hawaii， it would not have been unusual to hear：
[wild Hawaiian crow call]
That＇s the call of the Hawaiian crow. It＇s is a critically endangered species， now extinct in the wild after decades of habitat loss， persecution by farmers， and invasive diseases. In the mid-1990s， wildlife biologists rounded up the few surviving crows and put them into a captive breeding program. Today， Hawaiians can once again hear the calls of more than one hundred Hawaiian crows – or ＇alalā， as it is called there – but only in aviaries.
[aviary crow call]
Researchers once focused their efforts primarily on breeding and husbandry. But now they need to know more.
＂And now that they are doing so well， and it＇s at the point where they could be in the wild again， now we can look at their vocalizations and their behaviors and things like that.＂
University of Hawaii bioacoustics researcher Ann Tanimoto. Those other aspects—culture， if you will—are critical for a species as socially complex as the ＇alalā.
Tanimoto and her team made recordings of captive-bred ＇alalā pairs at the Keauhou Bird Conservation Center in Volcano， Hawaii， and compared them to recordings made in the early 1990s by Fish and Wildlife Service biologists of the last few wild pairs.
＂The wild have more， almost double the number of alarm calls， than the aviary ＇alalā do. And they also have these really cool territorial broadcast calls they do in the wild
[Wild territorial call]
that weren＇t found in captivity.＂
The absence of the territorial call in captivity makes good sense， because captive birds have different territory demands than wild ones. It also makes sense that they would have fewer alarm calls， because captive birds don＇t experience the threat of predation. The study was published in the journal Animal Behaviour.
＂So we think that their vocalizations that are similar， aviary and wild， are more innate， so basically naturally inside of them. And those that differ are socially learned by being passed on generation to generation.＂
So what happens when the captive-bred birds are released？ They won＇t have the luxury of learning these calls from their ancestors.
＂It will definitely be interesting to determine if they will begin vocalizing something similar to those that they used in the wild before， or if they will begin vocalizing call types that are completely different than those that were in the wild previously.＂
In Hawaiian mythology， the ＇alalā are thought to lead souls to their final resting place near the Ka Lae volcano. With luck， scientists can help the rare species avoid their own journey to Ka Lae.
Thanks for listening for Scientific American — 60-Second Science Science. I＇m Jason Goldman.
這里是科學(xué)美國(guó)人——60秒科學(xué)。我是杰森·古德曼。
有一分鐘時(shí)間嗎？
很久以前，在夏威夷大島上聽(tīng)到烏鴉叫是司空見(jiàn)慣的事：
（野生夏威夷烏鴉的叫聲）
那是夏威夷烏鴉的呼聲。夏威夷烏鴉是極度瀕危物種，由于數(shù)十年來(lái)遭遇棲息地喪失、農(nóng)民的迫害和疾病侵襲，現(xiàn)在已經(jīng)在野外滅絕。在20世紀(jì)90年代中期，野生動(dòng)物生物學(xué)家把極少數(shù)幸存下來(lái)的烏鴉聚在一起，把它們納入圈養(yǎng)育種計(jì)劃。今天，夏威夷人可以再次聽(tīng)到100多只夏威夷烏鴉的叫聲了，夏威夷人把夏威夷烏鴉稱(chēng)為＇alalā，不過(guò)他們只有在鳥(niǎo)舍才能聽(tīng)到烏鴉的叫聲。
（養(yǎng)在鳥(niǎo)舍的烏鴉發(fā)出的叫聲）
研究人員曾經(jīng)把精力主要放在繁殖和飼養(yǎng)上。但是現(xiàn)在他們需要了解更多。
“現(xiàn)在，它們表現(xiàn)得很好，現(xiàn)在它們可以再次在野外生存了，所以我們可以對(duì)們的聲音和行為等進(jìn)行研究了。”
谷本安是夏威夷大學(xué)生物研究所的研究員?？梢哉f(shuō)，對(duì)像夏威夷烏鴉一樣具有社會(huì)復(fù)雜性的物種來(lái)說(shuō)，文化等方面至關(guān)重要。
谷本和她的團(tuán)隊(duì)錄下了夏威夷鳥(niǎo)類(lèi)保護(hù)中心圈養(yǎng)烏鴉的叫聲，然后同美國(guó)漁業(yè)與野生動(dòng)物局的生物學(xué)家在上世紀(jì)90年代錄下的聲音進(jìn)行了比較。
“與鳥(niǎo)舍烏鴉相比，野外烏鴉的報(bào)警鳴叫次數(shù)幾乎多了一倍。當(dāng)然，烏鴉在野外也發(fā)出了非?？岬念I(lǐng)土廣播鳴叫。
（野外的宣示領(lǐng)土叫聲）
而圈養(yǎng)烏鴉則沒(méi)有發(fā)出過(guò)這種叫聲?！?BR> 圈養(yǎng)烏鴉沒(méi)有領(lǐng)域叫聲完全可以說(shuō)得通，因?yàn)槿︷B(yǎng)烏鴉同野生烏鴉有不同的領(lǐng)土要求。另外，圈養(yǎng)烏鴉的報(bào)警鳴叫次數(shù)更少，因?yàn)樗鼈儾粫?huì)經(jīng)歷捕食的威脅，所以這也可以說(shuō)得通。這項(xiàng)研究結(jié)果發(fā)表在《動(dòng)物行為》期刊上。
“我們認(rèn)為鳥(niǎo)舍烏鴉的發(fā)聲和野生烏鴉的發(fā)聲很相似，這更多是與生俱來(lái)的，可以說(shuō)這是天生的。而那些不同的聲音是通過(guò)代代相傳的社會(huì)學(xué)習(xí)演變而來(lái)的?！?BR> 那當(dāng)圈養(yǎng)繁殖的鳥(niǎo)類(lèi)被釋放到大自然中會(huì)發(fā)生什么呢？它們并沒(méi)有機(jī)會(huì)從祖先那里學(xué)習(xí)這些叫聲。
“如果我們能確定它們是否開(kāi)始發(fā)出同此前在野外生活時(shí)類(lèi)似的聲音，或者它們是否開(kāi)始發(fā)出與在野外生活時(shí)完全不同的聲音，這一定會(huì)非常有趣?！?BR> 在夏威夷神話中，夏威夷烏鴉被認(rèn)為能將靈魂引導(dǎo)至最終安息之地——卡拉也火山附近。幸運(yùn)的是，科學(xué)家可以幫助珍稀物種不用去往卡拉也。
謝謝大家收聽(tīng)科學(xué)美國(guó)人——60秒科學(xué)。我是杰森·古德曼。
重點(diǎn)講解：
1. round up 使聚攏；使聚集；
例句：He had sought work as a cowboy， rounding up cattle.
他找了一份放牛的差事，負(fù)責(zé)把牛趕到一起。
2. once again 又一次；再次；
例句：Facts once again give the lie to the fallacy.
事實(shí)再一次揭穿了這一謊言。
3. make sense 可以理解；講得通；
例句：Jeff＇s explanation of this question doesn＇t make sense to me.
我覺(jué)得杰夫?qū)@個(gè)問(wèn)題的解釋說(shuō)不通。
4. pass on 將…傳給；將…交給；
例句：Everyone was struck by their readiness to pass on all they knew.
他們很愿意把自己的知識(shí)傳給別人，這給每個(gè)人都留下深刻印象。