Guild Composition and Niche Overlap of Insectivorous Birds in Evergreen Rainforest

Abstract

A guild is a group of species that have similar requirements of resource and foraging behavior. The knowledge of insectivorous guild could explain foraging patterns, niche exploitation, and competition in a tropical forest. This information could help to monitor the forest by understanding the guild composition and their response to the habitat condition. In order to describe the guild composition and niche overlap of insectivorous birds, we observed all of the individual birds found foraging in the evergreen forest, Baluran National Park. Bray-Curtis similarity index and Pianka niche overlap index were used to analyze the data and grouping the birds into a guild. The cluster analysis consists of 27 bird species revealed 4 guilds: ground gleaner, foliage gleaner, aerial sallier, and bark prober. Based on species richness, foliage gleaner dominates the other groups while bark prober had the least species richness in the evergreen forest. The scarcities of feeding substrate affect guild existence and proved that the diversity of habitat substrate could affect the diversity of guild in an area. Ten congeneric species were found in this habitat and most of them are grouped into foliage gleaner. The junglefowl has the highest niche overlap than any other congeneric species. It seemed that the more specific the foraging substrate niche, the higher the competition among sympatric species. The level of congeneric/sympatric species competition could become the indicator to monitor a specific habitat or forest by understanding their niche partitioning, especially if the species is protected by the law.

Keywords

• foraging behavior
• foraging substrate
• competition
• niche partitioning