臺灣中部低海拔森林燕雀目鳥種灌叢巢與地面巢的天敵掠食風險

Predation Risk of the Shrub and Ground Nesting Passerines in a Disturbed Lowland Forest of Central Taiwan

陳宛均(Wan-Jyun Chen)

指導教授 ： 李培芬

國立臺灣大學/生命科學院/生態學與演化生物學研究所/碩士(2007年)

https://doi.org/10.6342/NTU.2007.01965

摘要

天敵掠食是造成小型燕雀目鳥類繁殖失敗的主因，而在不同的氣候區，由於動物群聚組成的差異，也會導致天敵組成有所不同。因此，親鳥理論上會選擇較安全的巢位，以躲避天敵來提高繁殖成功率。為了檢視上述假說，本研究於2006- 2007年繁殖季在雲林縣湖本村的低海拔森林內，分別針對在灌叢及地面築巢鳥類的繁殖成功率、巢位特徵、微棲地環境因子以及其鳥巢天敵進行研究，並比較不同巢位類型所面臨的天敵種類，及天敵出現與巢位特徵的關係。研究期間記錄了繡眼畫眉 (Alcippe morrisonia) (n=103) 及八色鳥 (Pitta nympha) (n=28) 等8種鳥類共205個鳥巢，其中依照築巢位置分成135個灌叢巢 (85個被天敵掠食，累積總觀察天數1331天) 與70個地面巢 (31個被天敵掠食，累積總觀察天數818天)，使用Mayfield estimator估算天敵掠食率的結果，顯示灌叢巢的每日天敵掠食率 (6.39±0.67%) 顯著高於地面巢 (3.79±0.67％, p <0.001)。天敵資料以24小時不間斷的錄影記錄鳥巢來直接獲取，並佐以被天敵掠食的鳥巢遺跡來判定天敵種類，結果發現熱帶、亞熱帶地區的天敵組成，與溫帶地區不甚相同。台灣亞熱帶低海拔森林的鳥巢天敵組成有鳥類、哺乳類、蛇類與螞蟻。其中蛇類為灌叢巢 (69.3.%) 與地面巢 (71.4%) 的共同主要掠食者，又以大頭蛇 (Boiga kraepelini)、赤背松柏根 (Oligodon formosanus) 與龜殼花 (Trimeresurus mucrosquamatus) 最為常見；灌叢巢的次要掠食者為鳥類與台灣獼猴 (Macaca cyclopsis)，地面巢則是須面對食蟹獴 (Herpestes urva) 與白鼻心 (Paguma larvata taivana) 等在地面活動的哺乳類天敵。並使用Mayfield 邏輯迴歸分析環境因子與天敵之間的關係，發現每種天敵各自擁有其獨特的掠食策略，且溫帶氣候區鳥類研究人員所重視的視覺遮蔽度假說，並不完全適用於蛇類掠食壓力沉重的熱帶、亞熱帶氣候區。而所謂安全的巢位與當地天敵種類的組成有必然的關係。

關鍵字

亞熱帶氣候區 ； 台灣低海拔森林 ； 繁殖成功率 ； 巢位特徵 ； 鳥巢天敵 ； 隱蔽度 ； 天敵掠食風險

並列摘要

Predation is a primary cause of nest mortality in many nests of small passerines. And the difference of fauna causes different patterns of nest predation in temperate, tropical and subtropical region. Therefore bird would choose to select a safe nest-site to avoid predators. In order to determine the predation risks and to examine the effects of nest-site characteristics and nest microhabitat on nest success of small passerines with different nest types and with different nest predators, we monitored nesting success and identified predators of the shrub and the ground nests in a disturbed lowland forest in Huben Village, Yunlin County during two breeding seasons in 2006-2007. In total, we monitored eight species 205 nests included White-eyed Nun babbler (Alcippe Morrisonia) (n=103) and Fairy Pitta (Pitta nympha) (n=28), they were 135 shrub nests (85 predated nests, 1,331 observation days) and 70 ground nests (31 predated nests, 818 observation days). Nest daily predation rates were calculated using the Mayfield estima- tor. The nest daily predation rate of shrub nests (6.39±0.67%) was significantly higher than ground nests (3.79±0.67%, p <0.001). Nest predators were directly observed by use of digital video systems being used continuously to monitor active nests. We also based on documenting depredated nest condition and recording dental marks of predators to get the indirect evidence. Nest predators in the subtropical lowland forest included birds, mammals, snakes and ants. Snakes were the most important predators to both the ground nests (71.4%) and the shrub nests (69.3%). Among the snake predators, Taiwan tree snake (Boiga kraepelini), Taiwan kukri snake (Oligodon formosanus) and Pointed- scaled pitviper (Trimeresurus mucrosquamatus) were responsible for most predation events. While the shrub nests were more susceptible to birds and Formosan Macaque (Macaca cyclopsis), the ground nests were often predated by the ground-dwelling Crabeating mongoose (Herpestes urva) and Formosan gemfaced civet (Paguma larvata taivana). Finally, we used Mayfield logistic regression to analyze the relationship of predators and environmental factors, and also found that each type of predator searches for its prey in a different manner. The safety and success of nest sites of small passerines depended on the composition of nest predators in the area where they lived.

並列關鍵字

subtropical region ； Taiwan disturbed lowland forest ； nest survival rate ； nest characteristics ； nest predator ； concealment ； nest predation risk

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