Foraging strata and dietary preferences of fifteen species of babblers in Sarawak, Malaysia

Abstract

Babblers are the primary insectivorous birds of the tropical forests in southeastern Asia which have shown to be affected by forest disturbance. Their high diversity, microhabitat specificity and specialised feeding guilds provide a good opportunity for ecological research pertaining to niche segregation. We examined the diet and foraging strata of 15 sympatric babbler species mist-netted in nine forests in Sarawak, eastern Malaysia. Based on 222 birds captured from December 2014 to March 2016, a segregation in foraging strata was found, with half of the species captured frequenting low strata, while only three were found at mid strata and four at high strata. Both species richness and abundance were found to decrease when the foraging height increased. From a total of 136 prey items retrieved from regurgitated and faecal samples of 13 babbler species, we found that Coleoptera (41.5%), Hymenoptera (36.2%), and Araneae (12.3%) formed the major diet of the birds. Diet overlaps among the babblers were relatively low. Our study demonstrated the possible presence of spatial and trophic niche segregation among babblers, and justified their ecological role as indicators of tropical forest ecosystem health, especially in the case of specialists, that deserve further conservation attention.