High-throughput sequencing reveals dietary segregation in Malaysian babblers

The coexistence of numerous species within a community results from how those species use available resources.Babblers are one of the major groups of Malaysian insectivorous birds,which frequently forage in dense vegetation cover and have a high level of sympatry.Therefore,examining the diet,prey selection,and niche segregation of babblers can be challenging.In this study,we used high-throughput sequencing to investigate potential dietary overlap or segregation among 10 babbler species of the 4 genera of the family Pellorneidae and Timaliidae:Pellorneum,Malacopteron,Stachyris,and Cyanoderma in central peninsular Malaysia.We tested the hypothesis that trophically similar species may differ in resource use to avoid competitive exclusion.We identified 81 distinct arthropod taxa from fecal samples,belonging to 71 families representing 13 orders,which were predominantly from 16 dipteran,13 lepidopteran,and 10 coleopteran families.Of all the prey taxa consumed,45%were found to be distinct across the 10 babbler species,and<35%were shared simultaneously by≥3 babbler species,indicating minimal dietary overlap.The black-throated babbler Stachyris nigricollis and moustached babbler Malacopteron magnirostre had the most generalist tendencies because they consumed a greater variety of prey taxa.Small dietary overlap values(Ojk)and a relatively wide range of food resources suggest that dietary segregation occurred among the studied babblers.The great diversity of prey consumed revealed the presence of dietary flexibility among the sympatric insectivorous birds,thus reducing any active dietary competition and facilitating the coexistence through niche partitioning.

Recovery of bird communities following the construction of a large-scale hydroelectric dam

Background:Habitat degradation is known to have a major impact on the composition of bird communities,yet how these communities recover following such disturbance is less understood.This study examined bird community changes from pre-logging to recovery over the course of habitat disturbance caused by the development of the Hulu Terengganu Hydroelectric Dam Project in Peninsular Malaysia,between 2007 and 2018.Bird surveys were conducted using point count observations and mist netting in the dam area from the prelogging phase until the operation phase.Results:It was observed that while bird species significantly declined after large-scale habitat clearance between the pre-logging and construction phases,they showed positive signs of recovery from the inundation to operation phases.These findings indicate that the bird community is still recovering,and the permanent loss of habitat required by most of the original species has not occurred,as evidenced by recolonisation.Bird species composition differed across phases due to varying habitat conditions.The turnover rate and immigration rate(recolonisation and newly recorded species)were higher between the construction and operation phases.It was also observed that insectivorous birds were more heavily affected than others by changes to the landscape,which highlights the versatility,survivability and tolerance of certain species to extreme disturbance and habitat modification.Conclusion:Although the operation phase showed an incremental change in bird species richness due to recolonisation and newly recorded species,this value remains far from that of the pre-logging phase.We predict that bird species recovery will continue to increase for some time before reaching a plateau among the newly created islands,reservoir and catchment area of the dam.