Diversity And Foraging Behaviour Of Insectivorous Birds In Limestone Areas In Lenggong Valley, Perak
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Date
2012-05
Authors
Mansor, Mohammad Saiful
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Publisher
Universiti Sains Malaysia
Abstract
Bird surveys were conducted in the Bukit Kepala Gajah limestone area in Lenggong Valley, Perak from July 2010 to July 2011. The main objectives of this study were to describe the foraging patterns of insectivorous birds in lowland rainforest, and to compare the foraging strategies of insectivorous birds in the continuous and small forest patches. In addition, this study were to determine the influences of initial and sequential observation methods on foraging data of birds, and to examine the influences of habitat structure and disturbance on the bird species composition. A point-count distance sampling method and observations (initial and sequential) for each foraging bird were used in this study. Observations for each foraging bird were made using 8 × 42 binoculars, recorded on micro-cassette, and later transcribed to data sheets. A total of 7789 bird detections were recorded, representing 100 bird species belonging to 28 families. The species richness of insectivorous birds differed significantly among the forest zones sampled, with more insectivorous birds occurring in the forest interior. No significant differences were found among the zones in the species richness of either the frugivore guild or the composite of other feeding guilds (omnivores, carnivores, nectarivores, granivores). Study of the foraging ecology of insectivorous birds examines how the trophically similar species can coexist in the same habitat, a central question in ecology. The foraging height and the parameters of the attack manoeuvres effectively divided the birds into three primary subguilds: (1) ‘High-sally insectivores’ – birds that foraged in higher strata using sallying tactics; (2) ‘High-foliage insectivores’ – birds that foraged in higher strata using leaf substrate; and (3) ‘Understory insectivores’ – birds that foraged in lower strata. Except for Asian Paradise-flycatcher and Asian Brown Flycatcher, no other two species used similar foraging heights, substrates and attack manoeuvres at the same time. However, the use of foliage density differed significantly between these two species. Four focal insectivorous bird species exhibited different response in the small forest patches, in terms of foraging height, attack manoeuvres and foliage density.
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Keywords
Diversity and foraging behaviour of insectivorous birds , limestone areas in Lenggong Valley, Perak