玉山國家公園楠梓仙溪林道食蟲性蝙蝠食性初探

Food Habits of Insectivorous Bats in the Na-Zu-Sen River Area of Yushan National Park

研究動物的食性與當地食物資源的狀況，可幫助瞭解動物如何利用其棲息環境中的資源，以獲得所需要的能量和營養。食蟲性蝙蝠所捕食的昆蟲種類可能因為種類、性別、年齡、生理狀態、季節等因素而有所差異。玉山國家公園境內已陸續發現共計4科22種食蟲性蝙蝠，可謂相當豐富，但這些蝙蝠的食性及生存所需的生態相關因子迄今仍不甚清楚。本研究以2007～2009年間於楠梓仙溪林道區域調查所發現的13種食蟲性蝙蝠所採得之排遺，進行分析以探討其食性。排遺中可辨識的節肢動物碎片計有7目昆蟲，包括雙翅目、鞘翅目、嚙蟲目、脈翅目、半翅目（含同翅亞目）、膜翅目與鱗翅目，以及蛛形綱之碎片。鞘翅目昆蟲的碎片在蝙蝠排遺中的出現頻度最高（82.8％），出現頻度次高者為雙翅目與蛛形綱（皆為53.4％），鱗翅目（48.3％）昆蟲為出現頻度第三高的食物類群。鞘翅目昆蟲的碎片在蝙蝠排遺中的相對重要性最高（75.8％），13種蝙蝠中有11種會捕食鞘翅目昆蟲；次高者為蛛形綱（17.8％），有7種蝙蝠會捕食取用；雖然亦有7種蝙蝠會捕食雙翅目昆蟲，但相對重要性僅2.4％（第三高的食物類群）。當地優勢物種寬吻鼠耳蝠及長趾鼠耳蝠之食性無太大差異，主要取食鞘翅目、蛛形綱與雙翅目，兩者不僅是獵捕空中昆蟲的物種（aerial hawk），亦具有撿食者（gleaner）的覓食習性。當無長趾鼠耳蝠出現的季節，寬吻鼠耳蝠會增加對雙翅目與蛛形綱的利用，減少對鞘翅目昆蟲的利用，推知此兩種優勢蝙蝠應具有明顯的競爭壓力。此外，寬吻鼠耳蝠在性別間的食性並無差異，而乾季時，蛛形綱的重要性比例明顯高於濕季。

Study on animals' diet and local food sources are important for understanding how the animals utilize the resources to meet their energy and nutritional requirements. Insectivorous bats may utilize different kinds of insects as their diet due to their differences in species, sex, age, breeding status, and seasonal factors. There are at least 22 species of the insectivorous bats belonging to 3 families that have been reported from the Yushan National Park for the past few years, but their foraging ecology remained unclear. We collected and analyzed feces pellets of 13 species of the insectivorous bats of the 3 families from the Na-Zu-Sen River area of the Park in 2004 and during the period from 2007 to 2009. The pellets contained remains of 7 orders of insects: Diptera, Coleoptera, Corrodentia, Neuroptera, Hemiptera (including Homoptera), Hymenoptera, Lepidoptera, and Arachnida. The frequency of occurrence was highest for Coleoptera (82.8%) and then followed by Diptera (53.4%), Arachnida (53.4%), and Lepidoptera (48.3%). The relative importance was highest for Coleoptera (75.8%) that was utilized by 11 bat species, and then Arachnida (17.8%) by 7 species. Although Diptera was also found in the feces pellets of 7 bats species, but its relative importance was only 2.4%. There was no significant discrepancy in food choice between two dominant Myotis species (Myotis latirostris and Myotis sp.2). Their main diet was Coleoptera, Arachnida and Diptera, indicating that they were aerial hawk, catching insects in the air and gleaning spiders on the ground. M. latirostris fed more on Diptera and Arachnida, and less on Coleoptera in the seasons when there was no Myotis sp.2, suggesting that there was strong competition in foraging between this two species. There was no significant sexual difference in food habit for M. latirostris, and its relative importance was higher for Arachnida in the dry season than in the wet season.