在美國(guó)德克薩斯州音樂(lè)之城奧斯汀,，生活著一群群散發(fā)著難聞氣味,、酷似狗臉的“歌手”,，它們會(huì)用非常復(fù)雜的樂(lè)調(diào)向雌性求愛(ài),。原來(lái),，這些歌手是巴西無(wú)尾蝙蝠,，日前，科學(xué)家最新一項(xiàng)研究顯示,，它們的歌聲混合著鳥(niǎo)鳴和鯨的聲音,，是唯一一種在求愛(ài)期使用音樂(lè)語(yǔ)言的哺乳動(dòng)物。
它們也被稱為墨西哥無(wú)尾蝙蝠,，在奧斯汀市德克薩斯州農(nóng)工大學(xué)的足球場(chǎng)四處可見(jiàn)它們的蹤影,。基于無(wú)尾蝙蝠所在位置的錄音記錄,，研究人員發(fā)現(xiàn)這種蝙蝠的聲音包含著鳥(niǎo)鳴,、嗡嗡聲和囀聲等在內(nèi)的不同語(yǔ)調(diào)。雄性蝙蝠會(huì)在懸掛或者是側(cè)面飛行中歌唱,，有時(shí)還會(huì)拍打著翅膀,，并滴下散發(fā)著難聞氣味的液體，從而吸引雌性蝙蝠的注意,。
德克薩斯州農(nóng)工大學(xué)生物學(xué)博士后柯?tīng)査诡D-博恩(Kirsten Bohn)是該項(xiàng)研究負(fù)責(zé)人,，他說(shuō)：“這是一種不同尋常的行為特征，它向我們揭示了墨西哥無(wú)尾蝙蝠非常獨(dú)特的性交配方式,。它們是一種會(huì)唱情歌的哺乳動(dòng)物,！”
正常情況下，這種蝙蝠的情歌對(duì)人類而言聽(tīng)起來(lái)就像快速的嗡嗡聲響,，這是由于其中多數(shù)樂(lè)調(diào)對(duì)人類來(lái)說(shuō)過(guò)高,，很難探測(cè)到。但是當(dāng)研究人員減緩情歌的播放速度,，他們能夠聽(tīng)到由特殊音節(jié)構(gòu)成的音調(diào),，聽(tīng)起來(lái)像是由多種聲音混合在一起形成的。
博恩稱,，“蝙蝠情歌”中的分級(jí)結(jié)構(gòu)能夠從其它多種哺乳動(dòng)物的重復(fù)性噪音中辨別出來(lái),，該研究小組還發(fā)現(xiàn)這種情歌中具有較高的系統(tǒng)性，比如：這些樂(lè)調(diào)總是以鳥(niǎo)鳴作為開(kāi)頭,，最終嗡嗡聲結(jié)束,。此外,，它們發(fā)出的每一首情歌都是獨(dú)特的,，與之前的情歌都是完全不同的。
它們聽(tīng)起來(lái)就像是具有天賦的爵士樂(lè)音樂(lè)家,，蝙蝠本能地結(jié)合不同長(zhǎng)度的樂(lè)調(diào)形成每首情歌,，博恩說(shuō)：“起初我認(rèn)為每只蝙蝠都會(huì)有類似的情歌樂(lè)調(diào)，但實(shí)際上每只蝙蝠都有復(fù)雜的樂(lè)調(diào)組合,。”這項(xiàng)研究發(fā)表在8月25日出版的《公共科學(xué)圖書(shū)館·綜合》(PLoS One)雜志上,。（生物谷Bioon.com）
生物谷推薦原始出處：
PLoS ONE 4(8): e6746. doi:10.1371/journal.pone.0006746
Versatility and Stereotypy of Free-Tailed Bat Songs
Kirsten M. Bohn1,2*, Barbara Schmidt-French3, Christine Schwartz2, Michael Smotherman2, George D. Pollak1
1 Department of Biology, Texas A&M University, College Station, Texas, United States of America, 2 Section of Neurobiology, University of Texas at Austin, Austin, Texas, United States of America, 3 Bat Conservation International, Austin, Texas, United States of America
In mammals, complex songs are uncommon and few studies have examined song composition or the order of elements in songs, particularly with respect to regional and individual variation. In this study we examine how syllables and phrases are ordered and combined, ie “syntax”, of the song of Tadarida brasiliensis, the Brazilian free-tailed bat. Specifically, we test whether phrase and song composition differ among individuals and between two regions, we determine variability across renditions within individuals, and test whether phrases are randomly ordered and combined. We report three major findings. First, song phrases were highly stereotyped across two regions, so much so that some songs from the two colonies were almost indistinguishable. All males produced songs with the same four types of syllables and the same three types of phrases. Second, we found that although song construction was similar across regions, the number of syllables within phrases, and the number and order of phrases in songs varied greatly within and among individuals. Last, we determined that phrase order, although diverse, deviated from random models. We found broad scale phrase-order rules and certain higher order combinations that were highly preferred. We conclude that free-tailed bat songs are composed of highly stereotyped phrases hierarchically organized by a common set of syntactical rules. However, within global species-specific patterns, songs male free-tailed bats dynamically vary syllable number, phrase order, and phrase repetitions across song renditions.
