大彎嘴雄鳥的歌曲量及分享行為

Repertoire Size and Song Sharing of Male Black-necklaced Scimitar-babblers (Pomatorhinus erythrocnemis)

歌曲是燕雀目鳴禽個體間用來溝通的重要媒介。歌曲量（repertoire size）常被認為是性擇的結果，歌曲量愈多愈有利於吸引雌鳥及防禦領域，但另一類假說則認為歌曲量的主要功能是令雄鳥可與相鄰雄性個體間進行歌曲分享（sharing hypothesis），並為彼此帶來好處。本研究以台灣特有且領域性強烈的大彎嘴（Pomatorhinus erythrocnemis）為對象，於2008年3-10月在雲林縣林內鄉湖本村蒐集領域相鄰雄鳥的歌曲，分析其歌型（song type）、歌曲量及歌曲特徵，並進一步探討鄰居間歌曲分享行為。結果顯示，在12隻雄鳥中共可分出22種歌型，各歌型以兩音節為主，歌曲音節頻率範圍在1,166～1,852 Hz之間，頻寬為570 Hz，歌曲長度為0.406 sec。每隻雄鳥的歌曲量在4-10首之間，平均為7.17首。12隻雄鳥彼此間分享歌曲數在2-7首間，平均為3.82首。個體間歌曲分享程度與領域空間距離或間隔數皆呈顯著的弱負相關，結果符合分享假說的預測，但分享行為的空間變異，仍待未來透過更大時空範圍的研究來加以釐清。

Song repertoires are thought to have evolved from sexual selection, with larger repertoires being advantageous in both female choice and territory defense. While an alternative hypothesis emphasizes that song repertoires evolved to allow song sharing with multiple neighboring males which could benefit from the signals being conveyed. In this study, we collected male songs of territorial black-necklaced scimitar-babblers (Pomatorhinus erythrocnemis) in Huben Village in central-west Taiwan from March to October 2008 to study their song characteristics, repertoires size and song sharing among neighbors. After sorting and examining all of the sonograms collected from 12 studied males, we identified 22 song types. The song characteristics ranged from 1,166-1,852 Hz in frequency and 0.406 ± 0.103 sec in duration. Each male had 7.17 song types on average and ranged from 4 to 10 song types. Furthermore, averagely each male shared 3.82 songs with other studied males and the number of shared songs ranged from 2 to 7. Moreover, the song type similarity between two males was weak but significantly inversely proportional to the distance between territories. According to the results listed above, the research evidenced the prediction of the sharing hypothesis, but further studies are needed to explore the larger spatial and temporal pattern of song sharing behavior in black-necklaced scimitar-babblers.