Habitat Disturbance and the Ecology of Small Mammals in the Philippines

Eric A Ricart, Danilo S Balete, Lawrence R Heaney
Vol 10 No 1 (2007), pp. 34-41




The unique mammal fauna of the Philippines, which includes one of the highest concentration of endemic species in the world, is dependent on natural forest habitats. Currently, perhaps less than 8% of the original primary forest cover of the Philippines remains intact, although many areas retain disturbed forest or support second-growth. Recent field surveys conducted across gradients of habitat disturbance reveal how native and non-native small mammals (rodents and insectivores) respond to disturbance. In general, non-native pest species are restricted to areas of heavy human disturbance where they may become very abundant. On geologically young islands where there are few native species, some non-natives may be common in undisturbed mature forest. On older islands with many native species, non-natives are absent or very rare in mature forest, although they often occur in remote disturbed sites that are surrounded by mature forest. In general, native species are most diverse and abundant in habitats that are relatively undisturbed, but many occur in disturbed forest and some persist in second-growth. A few native species reach peak abundance in moderately disturbed habitats. Occurrence patterns indicate that non-native species readily colonize disturbance sites and are predominant in severely disturbed habitat, but are unable to invade areas of intact forest that support rich communities of native small mammals. Native species have variable tolerance for disturbance; many can persist in moderately disturbed habitat and can re-colonize areas that have been severely disturbed (i.e., deforested) if such areas are allowed to regenerate. These results suggest that protection of remaining forests together with restoration of degraded habitats can be an effective conservation strategy for native small mammals.


Keywords: mammals, habitat disturbance gradients, forest, native, non-native

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