入侵種埃及聖鹮棲地選擇與生殖生態

Abstract

埃及聖鹮(Threskiornis aethiopica)常因動物貿易而被引入至世界各地，逃逸至野外後，已在當地對多種原生鳥類造成危害。埃及聖鹮亦經由動物園而引入台灣，目前臺灣西部各縣市沿海濕地已逐漸有其族群分布，顯示聖鹮已成功入侵。然而至今對聖鹮的族群數量、棲地偏好與生殖生態仍無較完整的研究，故本研究的目的為：(1)調查聖鹮在臺灣地區的族群數量及其棲地分布；(2)研究關渡地區族群的棲地利用偏好；(3)觀察並記錄關渡地區繁殖族群的生殖生態；(4)以生殖干擾的方式對聖鹮進行防治方法的測試。族群分布調查分別在2009年的3、6、9、12月和2010年的3、10月進行，以穿越線法調查宜蘭及西部沿海的主要河口及濕地，記錄其族群量和使用的棲地類型；棲地偏好的調查則在2009年的2-12月，於關渡自然公園使用定點觀察法記錄9:00-17:00間每15分鐘的聖鹮隻數、行為和使用之棲地類型，且每月至少有兩次不同週的紀錄；生殖生態同樣在關渡紅樹林於2009年4-8月和2010年3-9月進行聖鹮巢位觀察，以每週兩次的頻率記錄每巢蛋數和幼鳥數，並在2010年噴灑玉米油於蛋上，測試生殖干擾對聖鹮的防治效果。結果發現聖鹮族群主要仍分布於北部的河口濕地，但對農田、淡水泥灘、樹林則有季節性的利用。關渡地區的聖鹮族群較偏好在鹹水泥灘覓食，對農田和淡水泥灘則為季節性的利用；繁殖時偏好在紅樹林休息，非繁殖時則偏好在農田及淡水泥灘休息。關渡聖鹮族群在2009年的平均窩卵數為2.43±0.60顆，2010年為2.57±0.54顆；繁殖成功率2009年為0.24±0.37，2010年為0.35±0.36，窩卵數、孵化率、離巢率和繁殖成功率在年間皆無顯著差異，只有風速大和巢高低對幼鳥離巢率有顯著的負面影響。2010年的孵蛋期為19.3+3.35天，育雛期為18.4+4.36天，且兩年皆在一個繁殖季內有兩次繁殖高峰期。因而可以推論臺灣有許多適合聖鹮生存的潛在棲地，而聖鹮機會主義的棲地利用方式，以及每年兩次的繁殖高峰與穩定的繁殖成功率，其族群具有生存及擴張的優勢。而噴灑玉米油能顯著的抑制聖鹮蛋的孵化，並使親鳥不會立即棄巢且繼續在巢上孵蛋，是有效且符合經濟效益的防治方法。

Sacred Ibis (Threskiornis aethiopica) was usually transported to many places of the world by animal trades. After introduced to the wild, it has threatened many native bird species. Sacred Ibis was also introduced in Taiwan by zoo, and has successful invaded many wetlands of western counties. Because there is no complete study of their habitat and breeding ecology, the aims of this study is (1) to survey their population and record habitat; (2) to analyze their habitat preference in guandu area; (3) to record their breeding ecology in mangrove of guandu. (4) to test population managing method by spreading corn oil. The population surveys were carried out March, June, September, December 2009 and March, October 2010 across various counties and cities in western Taiwan and Yilan County. Habitat preference researches were conduct at least two times in different weeks of month from February to December in 2009, and used site observation to record their population size, behavior and habitat type from 9:00 to 17:00. Reproductive monitoring were also carried out in mangrove of Guandu twice a week to record numbers of egg and chick from April to August in 2009, and March to September in 2010. Furthermore, we conducted egg spreading of corn oil in 2010 to test the effect of breeding interference. The results show that population of sacred ibis were still distribution in wetlands of northern Taiwan, but habitat use of farmlands and fishponds in middle and southern Taiwan were raised in non-breeding season. We also found sacred ibis prefer salt-marsh to feed, but it has short preference to farmland and fresh-marsh. Mean clutch size of Breeding population in Guandu was 2.43±0.60 in 2009, and 2.57±0.54 in 2010. Average of breeding success rate was 0.24±0.37 in 2009, and 0.35±0.36 in 2010. There were no significant differences in clutch size, hatching, fledging and breeding success rate between 2009 and 2010. The incubating period was 19.3+3.35 days, and brooding period was 18.4+4.36 days. There were two breeding peaks in 2009 and 2010. We can infer that there still have many suitable places for sacred ibis in Taiwan. Because their opportunism of habitat use and two breeding peaks in one year, the population of sacred ibis has advantages of survive and spreading. But spreading of corn oil can significantly reduce their hatching success rate, and it is effective and inexpensive to manage their population.