大彎嘴 (Pomatorhinus erythrocnemis) 雄鳥歌曲歌型對應與歌曲重疊之意義

Abstract

先前的研究認為，雄性鳥類歌曲的對應 (song matching) 以及歌曲重疊 (song overlapping) 是具有攻擊意味的溝通訊號，然而，關於歌曲對應與歌曲重疊兩訊號之間的相互關係卻研究的非常少。為了解兩訊號間是否存在關係，本實驗設計對雄性大彎嘴進行回播操作。首先，我們探討歌曲歌型對應 (song type matching) 或者歌曲重疊 (song overlapping) 在大彎嘴 (Pomatorhinus erythrocnemis) 中是否具有意義。其次，我們將兩訊號結合，探討兩訊號加疊後，攻擊意味是否會增強。最後，我們在歌曲歌型對應操作中的後半段，加入歌曲重疊，探討經由循序漸進地將此兩訊號加疊，是否能增強攻擊意味。 大彎嘴為具較強領域性的鳥種，且平均個體所擁有的歌型數適中，適宜進行回播操作。本實驗以大彎嘴為對象，於2010至2011的繁殖季，在台灣新北市烏來山區對成年雄性個體進行回播，並同時錄製它們的歌聲與紀錄行為。回播所使用的大彎嘴歌型來自新竹、雲林以及嘉義的大彎嘴個體。 結果顯示，大彎嘴雄鳥在接受歌曲歌型對應回播時，其歌間間隔時間變化幅度會增加 (P=0.011)，且停留在距離播放器10公尺半徑內的時間較長 (P=0.039)。 雄鳥在接受歌曲重疊時，並沒有產生任何不同的反應。然而，當歌曲重疊與歌曲歌型對應同時發生時，雄鳥的歌聲變短 (P=0.030)；當歌曲歌型對應已回播一段時間之後再加入歌曲重疊時，雄鳥會增加唱歌次數 (P=0.0005) 且於回播時 (P=0.033)及回播後 (P=0.033) 停留在距離播放器10公尺半徑內的時間較長。 根據結果，我們做了以下結論：大彎嘴雄鳥的溝通行為中，歌曲歌型對應為一具有攻擊意味的訊號。歌曲歌型重疊只有在歌曲歌型對應同時發生；或者歌曲歌型對應已發生一段時間後加入，才為一具有攻擊意味的訊號，即歌曲歌型重疊為第二級訊號，當有必要表現出更強的攻擊意味時，才會伴隨著歌曲歌型對應出現。

Song type matching and song overlapping have been considered as aggressive signals in male songbirds. However, no studies have focused on the relationship between these two types of signals. To determine whether exposure to combine signaling increases aggression in songbirds, first, we evaluated the functions of song type matching and song overlapping in the Black-necklaced Scimitar Babblers (Pomatorhinus erythrocnemis). Second, we combined song type matching and song overlapping to examine is the combination a more aggressive signal. Lastly, we added overlapping in contest after type matching has already used for a while to examine that is song overlapping a second graded signal to escalate aggressive intention in the Black-necklaced Scimitar Babblers. The Black-necklaced Scimitar-Babblers, which exhibits strong reaction to intruders and possessed medium sized repertoire, was chosen as our subject. In the treatments interactive playback was used for recording their singing and behavioral responses. Field experiment was conducted during the breeding seasons of 2010 and 2011 at Wulai, New Taipei City, Taiwan. Interactive songs for playback were collected in Hsinchu, Yunlin and Chiayi. The results show that the male Black-necklaced Scimitar Babblers exhibited greater variation of song interval (P=0.011) and spent more time in a 10-meter circle from the speaker (P=0.039) when song-type matching treatments were conducted. Males did not exhibit responses that were different from control treatments compare to song overlapping treatments. However, when song overlapping and song type matching happened simultaneously, males exhibited shorter songs (P=0.030); when song overlapping was added in after song type matching had continued for a while, males responded stronger that they exhibited more number of songs (P=0.0005) and spent more time in a 10-meter circle from the speaker during playback (P=0.033) and post-playback period (P=0.033). We conclude that in song contests of the male Black-necklaced Scimitar Babblers, song-type matching may serve as an aggressive signal. Overlapping may serve as an aggressive signal if happens with song type matching simultaneously or with song type matching continues for a while. We conclude that song overlapping is a second graded signal to escalate aggressive intention in the Black-necklaced Scimitar Babblers if necessary.