RESPONSE OF A RAPTOR COMMUNITY TO SHRINKING AREA AND DEGRADATION OF TROPICAL RAIN-FOREST IN THE SOUTH WESTERN GHATS (INDIA)

The influence of irregular or incomplete fragmentation and increasing degradation of natural rain forest on diurnal raptor community was studied in the northern part of the western Ghats in southwestern India. A census of mainly territorial breeding pairs on 400 ha sample quadrats was associated with a measure of the percent cover of the main habitat types and a degree of forest fragmentation including irregular patch shape and habitat heterogeneity. Four groups of 3-4 species were defined according to their decreasing tolerance to forest fragmentation and disturbance, from mostly open grassland species to interior forest specialists. Habitat selection, density and sensitivity to landscape structure were investigated. The community composition and dynamic of each habitat were the sum of these specific reactions. The distribution of species along the succession of increasing fragmentation and forest degradation was thus found to be non random. but did not follow a nested subset pattern. The density of forest species declined with forest patch size possibly because of the irregular patch shape, the increased edge effects and the consequent increase of linear distance for a bird to cover within its territory. However, sensitivity to habitat structure and disturbance was found to be even higher than sensitivity to area per se. The need to conserve the largest patches of little disturbed forest is emphasized, as well as the conservation value of woodlots-open habitat mosaics that are suitable for a different set of species.