太魯閣國家公園五種高海拔森林鳥類對針葉樹之空間利用

Spatial Use of Conifers by Five Alpine Forest Birds in Taroko National Park, Taiwan

從1991年11月至1992年2月於太魯閣國家公園中橫段關原至大禹嶺一帶，海拔2,300-3,000m之間，利用一套四位數碼有系統地記錄5種高海拔森林鳥類對針葉樹的空間利用狀況。卡方分析顯示，不管是在高度層次、內外層次或樹木部位上，這5種鳥類的覓食頻率分布都出現顯著差異。而標準化殘差檢定進一步鑑定出這5種鳥類在高度層次上的差異主要來自於茶腹（Sittaeuropaea）比其他鳥種更常利用下層及頂層。而在內外層次及樹木部位上，卡方主要來自於茶腹與煤山雀（Parus ater）在覓食頻率分布上出現相反的趨勢。茶腹主要集中在內層的主幹及分枝上，而煤山雀大多出現在外層針葉上覓食。此外，青背山雀（Parus monticolus）及紅頭山雀（Aegithalos concinnus）都以小分枝及分枝為主要覓食區，不過青背山雀較集中於中層及外層。而火冠戴菊鳥（Regulus goodfellowi）的覓食區最分散，幾乎涵蓋整個樹冠層。這5種高海拔森林鳥類在非繁殖季時經常形成混種鳥群一起活動，足見在長期演化過程中，鳥種間可藉由資源分配來提升覓食效率，因而能共存共榮於同一個大環境中。 Foraging niches of five alpine forest birds on conifers were investigated with a systematic recording method in the Dayulin area of the Taroko National Park, Taiwan, November 1991 to February 1992. Eurasian nuthatch (Sitta europaea) was found to forage on trunks and main branches in the inner zone of the trees. Coal tit (Parus ater) was mostly on needles and twigs around the fringes. Both green-backed tit (Parus monticolus) and red-headed tit (Aegithalos concinnus) were frequently on twigs and branches; but the former tended to use more extensively in the middle and outer zones of the crown. Taiwanese firecrest (Regulus goodfellowi) was the most generalistic forager, using almost the whole crown. In the non-breeding season, these five species lived in coniferous forests, and usually foraged in compact flocks of mixed-species. The differences in their foraging niches might be resulted from resource partitioning to increase resources utilization.