鳳頭蒼鷹尾羽之觀察：不同年齡、性別間之比較

Differences in Tail Bars between Male and Female Crested Goshawk (Accipiter trivirgatus) of Various Maturities

張傳炯(Chuan-Chiung CHANG)

《台灣猛禽研究》 1期 (2003/09) Pp. 11-14

https://doi.org/10.30121/RRT.200309.0002

摘要

以4對繁殖配對的鳳頭蒼鷹（Accipiter trivirgatus）及其所孵出幼鳥7隻為對象，用單筒望遠鏡搭配數位相機，記錄尾羽之背面與腹面橫紋所顯現的特徵。雌、雄成鳥的10根中間尾羽均具4條濃色橫帶；濃、淡兩帶寬度略同；幼鳥則於4週大時長出第1條濃帶，8週時羽尾有4條濃帶，與成鳥同。有4隻幼鳥繼續追蹤到12～13週，其中2隻雌鳥再長出第5條濃帶，另外2隻雄鳥長到4條濃帶再加1淡色帶，其尾長比成鳥長了10～25%。雌成鳥之最外側尾羽如同中間尾羽具有明顯橫紋，但橫帶數目比中間尾羽多1條。有趣的是，除了最末端外，雄成鳥尾羽的腹面橫紋均退縮至羽軸上，並呈斑點狀，使兩性間尾羽之腹側有明顯差異，可最為性別分辨指標。幼鳥尾羽之腹面亦保持有兩性間差異，但除了先端橫紋外，其他班紋顏色淡化許多，特別是雄幼鳥實在很難看出有斑點的存在；此特徵可為分辨成鳥／亞成鳥之指標。

關鍵字

鳳頭蒼鷹 ； 尾羽橫帶 ； 兩性間差異

並列摘要

In 2002 and 2003, the patterns of tail bars as well as tail length of 4 breeding pairs and 7 juveniles of Crested Goshawk at Taipei Botanical Garden and Fushing Park were studied by means of digiscoping at 20-50x magnification. The adult tail contained 4 blackish bands, and no difference was found berween sexes in the central tail feathers. The growth of the tails of juveniles was followed for up to 11-13 weeks after hatching. Tails of juveniles increased in length by the addition of new bands, matching the adult’s length as well as number of bars by 8 weeks; the tail continued growing to a maximum at 11-13 weeks post-hatching. At the final stage, 2 female juveniles had 5 bars on the central feathers of the tail while male juveniles had 4 bars plus 1 faint bar, and the tails were 10%-25% longer than that of the adult.As to differences in the central tail feathers, the blackish bar of the outermost tail feathers, which can be seen from the ventral side, regressed to become irregular dot in males but not in female. This sexual dimorphism can be used for sex determination in Crested Goshawks and also for discrimination from the Besra(Accipiter virgatus) which has conspicuous, narrow black bars. However, were much fainter in juveniles and almost invisible in males except for the most-peripheral band.

並列關鍵字

Crested Goshawk ； tail bars ； sexual dimorphism