共域黃喉貂與黃鼠狼之食物資源分配

Abstract

相似物種在共域活動時經常發生資源分配的情形。在食肉目動物群聚中，種間競爭常是造成資源分配的主要原因。物種間資源分配的狀況常與牠們的體型大小相關，且資源的可得性以及物種的行為也常會影響物種間資源分配。本研究探討台灣南湖大山高山生態系中共域的兩種食肉目動物：黃喉貂（Martes flavigula chrysosphila）與黃鼠狼（Mustela sibirica taivana）之間食物資源分配的情形，同時調查牠們可能的重要食物資源(小獸類)的豐度，以檢視資源分配與資源可得性之間的關係。結果顯示黃喉貂與黃鼠狼均以小獸類為最主要食物，其次為大型哺乳動物。黃喉貂與黃鼠狼有相似的食性區位幅度，以及高度的食性重疊。兩物種間並未依其體型大小產生食物資源的分配，可能原因是黃鼠狼可以透過使用屍體的方式來取食大型哺乳動物。對黃喉貂與黃鼠狼這兩種機會主義廣食者而言，決定食物資源分配的型態，不受小獸類豐度消長的影響，而可能與其他類型食物在季節上的可得性有關。在冬季，小獸類雖然是有限的食物資源，但仍是兩種掠食者重要的食物來源。黃喉貂與黃鼠狼之間在某些特定食物類別上有分化的情形發生，但其分化程度並不足以使這兩種貂科動物避開食性上的重疊。

Similar species are often found to partition resources where they are sympatric. In carnivore community, interspecific competition is often considered an important force in forming resource partitioning. Resource partitioning among species usually corresponds to their body size. Moreover, resource availability and behavior of species may also influence resource partitioning. This study investigated food resource partitioning between two sympatric carnivores, yellow-throated marten (Martes flavigula chrysosphila) and Siberian weasel (Mustela sibirica taivana) in Nan-Hu Mountain, a high mountain ecosystem of Taiwan. The abundances of their possibly important food resources (small mammals) were also surveyed to examine the relationship between resource partitioning and resource availability. Results showed that both marten and weasel mainly preyed on small mammals, with large mammals as secondary diet item. Marten and weasel had similar diet niche breadth and high degree of diet overlap. The absence of resource partitioning related to predator body size is probably due to that weasel could also consume large mammals by exploiting their carrions. Resource partitioning between marten and weasel, both opportunistic generalists, was not in accordance to small mammal abundance but probably to seasonal availability of other food resources. Small mammals were limited resources but still important for both species in winter. Segregation in some food items between marten and weasel occurred but was not strong enough to allow the two mustelids to avoid overlap in diet.