都會化對鳥類繁殖表現與巢防禦行為的影響

Abstract

全球郊野環境的都會化非常快速且規模愈來愈大，特別是亞洲地區。這現象將直接衝擊野生動物的生態，包括棲地減少或破碎化，許多野生動物因此而族群減少甚至滅絕，但也有部分野生動物因為適應都會區的環境，族群量反而比原始環境多。本論文第一章簡述都會化的影響。二與第三章分別以臺灣都會區中已經建立族群的兩種猛禽，鳳頭蒼鷹(Accipiter trivigatus)與領角鴞(Otus lettia)為研究對象，比較牠們在都會區的繁殖表現。結果顯示，在產卵時間上，都會區族群會較原始環境提早，順利孵化巢的離巢幼鳥數也較原始環境多。整體而言，都會區繁殖成功率較原始區高。沒有天敵威脅及食物可獲得性高是兩種成功立足都會區猛禽的共同優勢。在第四章中，我以另一適應都會化的鳥種-臺灣夜鷹(Caprimulgus affinis)為對象，檢驗擬傷行為展現時機。都會區頂樓因為沒有相關遮蔽，提供一個絕佳機會驗證鳥類在遮蔽程度不一樣的情況下，巢防禦行為時機究竟是與"子代較易受威脅"或"子代數量"有關。結果顯示，在環境遮蔽度低的情況下，夜鷹母鳥會提早展現擬傷行為，與天敵的距離也會較近，擬傷展現的天數較久，以保護相對容易被偵測的幼鳥。相反地，在原始河床中，擬傷展現較晚同時也較早結束。Urbanization grows rapidly all over the world, especially in Asia region. This phenomenon would directly impact on the ecology of wildlife, including habitat reduction and fragmentation, and may lead to population decline or even cause local extinct. However, there are some wildlife that adapt well to urban environment and have more ethnicity than their original environment. The first chapter of this dissertation describes the influence of urbanization. In the second and third chapters, I presented the reproductive performance of two raptors, the Crested Goshawk (Accipiter trivigatus) and the Collared Scops Owls (Otus lettia), which re-established populations in metropolitan in Taiwan. We aimed to compare their breeding ecology between two environments. The results showed that urban raptors advanced timing of breeding. Furthermore, more young raised and fledged success in hatched nestings. Overall, urban raptors (both hawk and owl in this case) has higher breeding success chance than rural counterparts, and lower predation risk and year-round food supply might be two major factors that benefit these raptors. Urban environment also provides a great opportunity to test the optimal timing of nest defense. In chapter four, I presented injury-feigning behaviour (IFB) of the Savanna Nightjar (Caprimulgus affinis) between urban building rooftop and rural riverbank. The results showed that nightjar display IFB earlier on less-cryptic environment, females shorten the distance to predator when display IFB and extend the period to protect the relatively exposure chicks in urban environment.