The Distribution and Ecology of Mammals on Leyte, Bi I i ran. and Maripipi Islands, Philippines Eric A. Rickart Lawrence R. Heaney Paul D. Heideman Ruth C. B. Utzurrum Abstract The land mammal faunas of the Philippine islands of Leyte, Biliran, and Maripipi are described. Collectively, a total of 48 indigenous species are known to occur on the three islands: 45, 30, and 25 from Leyte, Biliran, and Maripipi, respectively. These include 1 insectivore, 1 dermopteran, 33 bats, 2 primates, 7 rodents, 2 carnivores, and 2 ungulates. All but three of these species occur on the large neighboring island of Mindanao. The exceptions include a widespread but rarely captured vespertilionid bat and two rodents that have sister-species on Mindanao. Among the remaining 45 species, 9 are restricted to the Mindanao faunal region, 10 are more widely distributed in the oceanic Philippines, and 26 have distributions that extend outside of the Philippines. One species from Biliran and two from Maripipi (all poorly known insectivorous bats) have not been recorded from Leyte. Otherwise the faunas of the two smaller islands are subsets of the Leyte fauna, which is, in turn, a subset of the Mindanao fauna. Data indicate that the present-day mammal faunas of these islands have been shaped primarily by events that occurred during the last 1 2,000 years. Results generally support predictions concerning elevational patterns in species richness and abundance (decreasing with elevation for small fruit bats, increasing with elevation for small non-volant species) and habitat associations of endemic versus non-endemic species (the former restricted to pristine or lightly disturbed habitats, the latter predominant in disturbed habitats). However, some of these patterns appear to break down on small land-bridge islands with relatively depauperate faunas. Most notably, commensal or widespread Asian species are abundant in undisturbed or lightly disturbed habitats when there are few endemic species present. Many of the results have direct implications for wildlife conservation in the Philippines. Patterns of deforestation render lowland species most vulnerable. Habitat associations of species indicate that disturbances to natural habitat have a disproportionately greater negative impact on the unique endemic portions of a local fauna. The depauperate nature of faunas on small land-bridge islands demonstrates that relatively large faunal reserves are required to provide long-term protection for many species. Furthermore, elevational range restrictions or special ecological requirements of some species necessitate reserves that encompass the full range of regional habitat diversity. Introduction Mindanao, principally because early work revealed many endemic species in these areas. As a The Philippine Islands support a diverse mam-result of this limited focus, the mammals of most mal fauna of about 1 70 species, many of which of the smaller Philippine islands remain poorly are endemic to the archipelago (Heaney, 1986, known. Recent studies on some small and medi1991a; Heaney et al, 1987). Most studies of Philum-sized islands in the archipelago have yielded ippine mammals have focused on the faunas of a wealth of information on patterns of mammalian the highlands of the two largest islands, Luzon and distribution (Heaney, 1986; Heaney et al, 1989, FIELDIANA: ZOOLOGY, N.S, NO. 72, AUGUST 31, 1993, PP. 1-62 1