Endemic butterflies on Grande Comore: habitat preferences and conservation priorities

Abstract

The island of Grande Comore (Comoro Islands, western Indian Ocean) has an endemic butterfly fauna threatened by rapid habitat change. Transect counts were used to assess the abundance and species richness of butterflies in different habitats, and along an elevational gradient. Species richness of non-endemic butterflies was highest in low elevation, man-modified habitats. In contrast, most endemic butterflies were confined to forest habitats, which only remain above 500m elevation. Richness and abundance of endemic butterflies were highest at the lower elevational limits of the remaining forest. Controlling for elevation, the richness of endemic butterflies was highest in mature forest where the gross structure of the forest remained intact, lower in scrubby secondary forest, and lowest in pioneer forest on old lava flows. The survival of the majority of the endemic butterflies may depend on forest conservation measures in the rapidly diminishing areas of mature forest at mid elevations.