无尾蝙蝠使用“情歌”和难闻气味向雌性求偶

在美国德克萨斯州音乐之城奥斯汀，生活着一群群散发着难闻气味、酷似狗脸的“歌手”，它们会用非常复杂的乐调向雌性求爱。原来，这些歌手是巴西无尾蝙蝠，日前，科学家最新一项研究显示，它们的歌声混合着鸟鸣和鲸的声音，是唯一一种在求爱期使用音乐语言的哺乳动物。

它们也被称为墨西哥无尾蝙蝠，在奥斯汀市德克萨斯州农工大学的足球场四处可见它们的踪影。基于无尾蝙蝠所在位置的录音记录，研究人员发现这种蝙蝠的声音包含着鸟鸣、嗡嗡声和啭声等在内的不同语调。雄性蝙蝠会在悬挂或者是侧面飞行中歌唱，有时还会拍打着翅膀，并滴下散发着难闻气味的液体，从而吸引雌性蝙蝠的注意。

德克萨斯州农工大学生物学博士后柯尔斯顿-博恩(Kirsten Bohn)是该项研究负责人，他说：“这是一种不同寻常的行为特征，它向我们揭示了墨西哥无尾蝙蝠非常独特的性交配方式。它们是一种会唱情歌的哺乳动物！”

正常情况下，这种蝙蝠的情歌对人类而言听起来就像快速的嗡嗡声响，这是由于其中多数乐调对人类来说过高，很难探测到。但是当研究人员减缓情歌的播放速度，他们能够听到由特殊音节构成的音调，听起来像是由多种声音混合在一起形成的。

博恩称，“蝙蝠情歌”中的分级结构能够从其它多种哺乳动物的重复性噪音中辨别出来，该研究小组还发现这种情歌中具有较高的系统性，比如：这些乐调总是以鸟鸣作为开头，最终嗡嗡声结束。此外，它们发出的每一首情歌都是独特的，与之前的情歌都是完全不同的。

它们听起来就像是具有天赋的爵士乐音乐家，蝙蝠本能地结合不同长度的乐调形成每首情歌，博恩说：“起初我认为每只蝙蝠都会有类似的情歌乐调，但实际上每只蝙蝠都有复杂的乐调组合。”这项研究发表在8月25日出版的《公共科学图书馆·综合》(PLoS One)杂志上。

推荐原始出处：

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.