Distribution and Ecology of Small Mammals along an Elevational Transect in Southeastern Luzon, Philippines

Abstract

Small mammals were surveyed along an elevational transect on Mount Isarog (summit at 1,966 m) in southeastern Luzon, Philippines. Removal trapping was conducted at six sites ranging from remnant dipterocarp forest (475 m) to mossy forest (1,750 m). A total of 255 small mammals was captured in 9,001 trap nights. Species captured were one shrew (Crocidura grayi) and seven rodents (Apomys musculus, Apomys cf. microdon, Archboldomys luzonensis, Batomys sp., Chrotomys gonzalesi, Rattus everetti, and Rhynchomys isarogensis). Five species are nocturnal, one diurnal, and two have variable diel activity. On the basis of trap success with two kinds of bait, analysis of stomach contents, and captive feeding trials, we recognize four trophic groups: omnivorous (three species), insectivorous (two species), granivorous-frugivorous (one species), and vermivorous (two species). Species richness and relative abundance followed predicted patterns of increase with elevation. Four species endemic to Mount Isarog were found only at high elevations.