小燕鷗巢位選擇與巢材功能之探討

Abstract

小燕鷗是臺灣二級珍貴稀有保育類動物，其主要的繁殖棲地有宜蘭縣蘭陽溪口沙洲、彰化縣崙尾工業區、澎湖縣青螺濕地與吉貝嶼以及嘉義縣新塭滯洪池沙洲。本研究於2013年5－7月調查小燕鷗在四地的巢位選擇並進一步在宜蘭縣蘭陽溪口沙洲深入探討小燕鷗的巢材功能。結果顯示，在巢位選擇上小燕鷗偏好環境複雜度高有枯枝木屑、碎石或貝殼的環境，並且偏好選擇遠離植被和植被高度低的環境作為巢位。若是大棲地的環境狀況較不適合小燕鷗，小燕鷗會透過巢位選擇來改善巢位的環境以補償大棲地造成的影響。本研究推測驅使小燕鷗巢位選擇偏好的原因可能和天敵的影響以及巢材的需求有關。在各繁殖地中，小燕鷗使用巢材的種類和比例不同，分別為宜蘭縣蘭陽溪口33%，彰化縣崙尾工業區沙丘與礫石地3%和82%、澎湖縣吉貝嶼28%、嘉義縣新塭滯洪池沙洲83%。經研究結果顯示∶小燕鷗使用巢材的原因和調節巢內微氣候有關，使其巢內溫度較低、濕度較高；然而，對於其孵化成功率、被捕食率、親鳥孵卵時間、蛋體積和產卵時程則沒有影響。2013年小燕鷗在宜蘭縣蘭陽溪口沙洲的孵化成功率為54.8%，是目前臺灣研究中最高的記錄，推測可能和當年颱風季節較晚開始有關。在氣候因子中，以孵化期的最大雨量、孵化期的平均溫度以及孵化期的平均溫度和平均風速的交互作用對於小燕鷗孵化成功率有顯著相關。然而，人為活動干擾一直是影響小燕鷗繁殖的主要原因，除了直接造成小燕鷗可利用的繁殖棲地減少，間接也影響了繁殖結果，因此瞭解小燕鷗對於棲地選擇的需求，對於其棲地的經營管理或未來要營造人工棲地是相當重要的資訊，而建立長期的棲地品質與小燕鷗族群動態的監測是未來可以的努力目標。

Little tern is listed as the category “Rare and Valuable Species” in the Schedule of Protected Species in Taiwan, and its main breeding habitats are Lanyang estuary in Yilan County, Lunwei industrial park in Changhua County, Jibeiyu in Penghu island, and Xinwen in Chiayi County. In this study, I investigated the nest site selection in the above breeding habitats and further explored the nest materials functions in Lanyang estuary from May to July, 2013. Results showed that little tern favored higher environmental complexity that with litter, debris and shell fragments and preferred the nest site that was far from vegetation and had lower vegetation height. These seemed to associate with predators and the needs for materials. The proportions of nest materials utilization in four habitats are Lanyang estuary 33%, Lunwei industrial park sand dune 3% and gravel 82%, Jibeiyu 28%, and Xinwen 83%. Using materials would benefit nest microclimate significantly, and keep nest temperature lower and nest humidity higher; however, there were no differences in hatching success, predation rate, parental incubation time, egg volume, egg-laying period. For abiotic factors, such like maximum precipitation in incubation period, average temperature in incubation period, and interaction between average temperature and average wind speed in incubation period, had the significant influence on hatching success. Because of late typhoon season in 2013, the hatching success (54.8%) in Lanyang estuary were the highest than ever before in Taiwan. In addition, human disturbance had posed critical impact on little terns’ breeding performance and habitat. Therefore, knowledge of habitat selection would benefit habitat management, conservation and restoration.