金門栗喉蜂虎生殖群規模對生殖成功之影響

栗喉蜂虎（Merops philippinus）是金門的夏候鳥，由於金門為牠們在台灣唯一的繁殖地，金門國家公園管理處於2002年開始為牠們營造人工生殖坡面。本研究欲了解生殖群規模不同，是否會對天敵有不同的吸引力，進而對栗喉蜂虎的生殖表現造成影響；此外也探討人工坡面的形質如何影響栗喉蜂虎的生殖表現。本研究於2016、2020及2021年6-7月，量測慈湖三角堡、青年農莊和青青農場裡各人工坡面的形質（巢間距離、坡面高度、裸露帶寬度與最近高點距離），共調查21個栗喉蜂虎生殖群的生殖成功、個體產出子代數與個體離巢時間；另於2020和2021年6-7月，監測天敵（鼠與蛇類、鳥類）在各坡面出現的頻率。　　21個生殖群規模在2-560巢之間，我發現12個生殖群整體生殖成功高於90%，顯示在調查期間生殖成功和生殖群規模無顯著關係（r2 = 0.0721，p = 0.239）。然而生殖群規模增加，個體平均產出子代數減少（p = 0.011），且有較早離巢的趨勢（p = 0.032）。在天敵監測結果，鼠與蛇天敵出現頻率極低（0-0.08隻次／天），鳥類天敵出現頻率則與生殖群規模呈顯著正相關（r2 = 0.4266，p = 0.0213）。在坡面形質部分，產出子代數與坡面高度（1.7-4m）呈顯著正相關（p = 0.008），離巢時間則與最近高點距離（0.5-31m）呈現顯著負相關（p = 0.011）。鼠與蛇類天敵為主要影響栗喉蜂虎生殖成功的因子，本研究推測鼠與蛇出現與否和周遭環境有關，而與生殖群規模無關。分析結果與野外觀察經驗皆顯示，栗喉蜂虎優先選擇高度高或面積大的坡面，一方面是大坡面有較多棲地忠實性個體而產生較強的社會性吸引，另一方面是由於大坡面及大生殖群較能減少天敵威脅，使栗喉蜂虎容忍生殖群規模大帶來的缺點，如體外寄生蟲與疾病。藉由了解生殖群規模對栗喉蜂虎生殖表現的影響，除了提供坡面營造建議，更期望運用於其他集體營巢鳥種的棲地經營管理。

關鍵字

集體營巢；天敵；子代數；棲地經營管理

並列摘要

Blue-tailed Bee-eaters (Merops philippinus) are summer migrant birds on Kinmen island. Since Kinmen is their only breeding area in Taiwan, Kinmen National Park has been building artificial sand slopes to facilitate the burrow for breeding since 2002. The purposes of this research are to understand the relationship between the colony size and breeding performance of Blue-tailed Bee-eater whether predators are likely to appear more in bigger colonies, and to comprehend how artificial slope characteristics influence their breeding performance. Data was collected from 21 breeding colonies, located in Triangle Fort, Qingnian Farm, and Qingqing Farm during June to July of 2016, 2020, and 2021. Breeding success, fledging number, fledging date, and morphology parameters were included. Frequency of predators (rodents, snakes, and predatory birds) appearance was monitored in years 2020 and 2021. The range of colony size in this study was 2-560 nests per colony. There was no statistically significant correlation between colony size and breeding success since the success rates of 12 colonies were higher than 90% (r2 = 0.0721，p = 0.239). In contrast with an increasing colony size, the average fledging number decreased (p = 0.011), and fledging date became earlier (p = 0.032). Rodent and snake predators were remarkably low in terms of appearance frequency (0-0.08 individual per day). Nonetheless, avian predator appearance frequency had positive correlation to the colony size (r2 = 0.4266，p = 0.0213). Fledging number was positively correlated with slope height (1.7-4m) (p = 0.008) and fledging date was negatively correlated with the distance to the nearest tree (0.5-31 m) (p = 0.011). Predators, such as rats and snakes, was the main factor affecting reproductive success of Blue-tailed Bee-eater. Their presence was considered to be related to the surrounding environment rather than colony size. Both analysis results and field observations suggested that Blue-tailed Bee-eaters preferred taller and larger slopes. Majority of the bee-eaters are more attracted to the larger and taller slopes due to site fidelity and social attraction characteristic. Furthermore, predator avoidance allows them to tolerate the disadvantages caused by larger colony size, such as ectoparasites and disease. By understanding the effects of colony size on the reproductive performance of Blue-tailed Bee-eater, this research not only provides advice on slope building, but also could be applied to habitat management of other colonial breeding birds.