The selection of incubation sites by the Philippine Megapode, Megapodius cumingii, in North Sulawesi, Indonesia

Abstract

The Sulawesi subspecies of the Philippine Megapode, Megapodius cumingii gilbertii, most commonly lays its eggs in decaying roots of dead trees. We measured 14 environmental variables describing the dead tree and surrounding forest at incubation sites and random points in the Tangkoko-DuaSudara Nature Reserve, North Sulawesi, Indonesia. Incubation sites were not selected randomly by the Philippine Megapode but were located in areas with specific environmental characteristics. A Discriminant Function Analysis produced a clear separation between incubation sites and random points based primarily on ten variables. Relative to random points, incubation sites were located at the base of very large dead trees, disproportionately Alstonia ranvolfia, with their trunks standing and unbroken, and root plates in the ground. Incubation sites were in areas that were less disturbed than random points, with a relatively high and closed canopy, more large trees, and a less dense understorey. We consider that variables associated with incubation sites provide in situ a large biomass of decaying roots (for heat generation from microbial decomposition) while being under a closed canopy (for protection from desiccation and fluctuations in air temperature). Research is required into the effects of habitat modification on the Philippine Megapode and other members of the Megapodiidae. Until such studies are undertaken, we recommend that resource managers protect areas of relatively undisturbed mature closed forest in order to conserve the Philippine Megapode.