栗喉蜂虎營巢地維護與評估(二)
2003 年我們在金門島監測栗喉蜂虎的繁殖族群量約500隻，昔果山的族群量仍最大，約有150隻。所選擇觀察的5個營巢地於5月11日開始產卵，進入繁殖季，於 7月25日所有幼鳥離巢，歷時兩個多月。栗喉蜂虎喜好在砂質土堆或金門層土堆的陡直坡面挖掘巢洞，進行繁殖。我們推測坡面上的可用築巢空間，可能是栗喉蜂虎選擇營巢地點時的關鍵因子之一。
因此今年度選擇了栗喉蜂虎曾使用過的四個營巢地，將一部分坡面加以整理、剷除舊巢洞為實驗組，另一部分則保留舊巢洞不做整理為對照組，紀錄栗喉蜂虎掘洞築巢的情形並追蹤其生殖成功。研究結果發現，實驗組的巢間距顯著高於對照組，築巢密度為邊緣不顯著（P=0.055），顯示整理後的坡面能提供較多的繁殖個體使用。在繁殖成功上，實驗組與對照組在幼鳥離巢率及巢成功無顯著差異。為了了解栗喉蜂虎選擇營巢棲地的因子，我們選取今年栗喉蜂虎有使用及未使用的營巢地，量測棲地微特徵、食物資源等，發現有使用和未使用營巢地的坡度、土壤穿透阻力、巢坡面前開闊度和食物資源間皆無顯著差異，可能另有其他因子影響蜂虎選擇營巢坡面。
今年栗喉蜂虎的夜棲地點和去年大致相同，只有在后沙村的夜棲點改變到隴口一帶的樹林，繁殖期後的總數量大約有2,000多隻，繁殖後成鳥和亞成鳥的比例約為1:2.3。明年將持續監測蜂虎繁殖族群數量及分布，同時也將進行坡面整理與乳山新營造棲地之繁殖成功追蹤，並將與國外學者合作從事其繁殖生態之深入研究。
關鍵字：栗喉蜂虎、族群分布、營巢棲地、繁殖成功、夜棲
Abstract
We monitored the Blue-tailed Bee-eater (Merops Philippinus) breeding population of about 500 individuals on KinmenIsland in 2003. the colony in ShiGouMt. with about 150 individuals was the biggest one. The first egg was laid on May 11 and the last fledgling left its nest burrow on July 25 from the five nest sites we monitored. The whole breeding season lasted about two months. The bee-eater preferred to nest on sandy or Kinmen layer substratum with vertical slope. We speculated the available nesting space of the slope was the limiting factor for bee-eaters to nest. Therefore, we selected four nest sites that bee-eaters had used before, cleaned up part of the vegetation and old nest burrows as experimental plots, and left the other unclean parts as control ones. We found that the distance between nests and nest density of experimental plots were lager than control ones indicating to clean up the old nest sites could provide more nesting space for bee-eaters in the following year. We measured the flying insect abundance and microhabitat features including the difference in slope gradient, soil pressure and openness of nest slope between used and unused nest sites. We found that there were no significant differences between them indicating there might be other factors affecting nest site selection. The night roosting sites stayed pretty much the same as last year. After breeding season, the bee-eater numbers were counted over 2,00 individuals. The ratio of adults and juveniles was 1:2.3. We will keep surveying bee-eater breeding population and nest sites, conducting old nest sites cleaning up experiment, and monitoring the newly man-made RueShen nest in 2004. at the same time, we will continue to establish international cooperation with American researchers on further investigation of bee-eaters’ breeding ecology.
Key words: blue-tailed bee eaters, population distribution, nest site, breeding success, night roosting
因此今年度選擇了栗喉蜂虎曾使用過的四個營巢地，將一部分坡面加以整理、剷除舊巢洞為實驗組，另一部分則保留舊巢洞不做整理為對照組，紀錄栗喉蜂虎掘洞築巢的情形並追蹤其生殖成功。研究結果發現，實驗組的巢間距顯著高於對照組，築巢密度為邊緣不顯著（P=0.055），顯示整理後的坡面能提供較多的繁殖個體使用。在繁殖成功上，實驗組與對照組在幼鳥離巢率及巢成功無顯著差異。為了了解栗喉蜂虎選擇營巢棲地的因子，我們選取今年栗喉蜂虎有使用及未使用的營巢地，量測棲地微特徵、食物資源等，發現有使用和未使用營巢地的坡度、土壤穿透阻力、巢坡面前開闊度和食物資源間皆無顯著差異，可能另有其他因子影響蜂虎選擇營巢坡面。
今年栗喉蜂虎的夜棲地點和去年大致相同，只有在后沙村的夜棲點改變到隴口一帶的樹林，繁殖期後的總數量大約有2,000多隻，繁殖後成鳥和亞成鳥的比例約為1:2.3。明年將持續監測蜂虎繁殖族群數量及分布，同時也將進行坡面整理與乳山新營造棲地之繁殖成功追蹤，並將與國外學者合作從事其繁殖生態之深入研究。
關鍵字：栗喉蜂虎、族群分布、營巢棲地、繁殖成功、夜棲
Abstract
We monitored the Blue-tailed Bee-eater (Merops Philippinus) breeding population of about 500 individuals on KinmenIsland in 2003. the colony in ShiGouMt. with about 150 individuals was the biggest one. The first egg was laid on May 11 and the last fledgling left its nest burrow on July 25 from the five nest sites we monitored. The whole breeding season lasted about two months. The bee-eater preferred to nest on sandy or Kinmen layer substratum with vertical slope. We speculated the available nesting space of the slope was the limiting factor for bee-eaters to nest. Therefore, we selected four nest sites that bee-eaters had used before, cleaned up part of the vegetation and old nest burrows as experimental plots, and left the other unclean parts as control ones. We found that the distance between nests and nest density of experimental plots were lager than control ones indicating to clean up the old nest sites could provide more nesting space for bee-eaters in the following year. We measured the flying insect abundance and microhabitat features including the difference in slope gradient, soil pressure and openness of nest slope between used and unused nest sites. We found that there were no significant differences between them indicating there might be other factors affecting nest site selection. The night roosting sites stayed pretty much the same as last year. After breeding season, the bee-eater numbers were counted over 2,00 individuals. The ratio of adults and juveniles was 1:2.3. We will keep surveying bee-eater breeding population and nest sites, conducting old nest sites cleaning up experiment, and monitoring the newly man-made RueShen nest in 2004. at the same time, we will continue to establish international cooperation with American researchers on further investigation of bee-eaters’ breeding ecology.
Key words: blue-tailed bee eaters, population distribution, nest site, breeding success, night roosting