Effects of habitat degradation on mixed-species bird flocks in Indian rain forests

Sridhar, Hari and Sankar, K (2008) Effects of habitat degradation on mixed-species bird flocks in Indian rain forests. In: Journal of Tropical Ecology, 24 (2). pp. 135-147.

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Abstract

Habitat degradation affects mixed-species bird flocks (flock hereafter) through two mechanisms – changes in the bird community from which flocks are drawn and changes in the propensities of species to flock. We determined the relative influence of these two mechanisms by examining variation in flocks across nine rain-forest fragments (range 11–2600ha) in a plantation landscape in the Western Ghats, India. We found differences between fragments in average number of species (range 10.8–15.2) and individuals (range 19.0–37.6) per flock, number of species that participated in flocks (range 34–59), encounter rates (range 0.5–2.4 flocks $h^{-1}$) and flock composition. Multiple regression and randomization tests revealed that different mechanisms contributed to this variation. Three flock variables (open-forest individuals per flock, total open-forest species that participated in flocks in a fragment, flock composition) mainly reflected changes in the bird communities of fragments. Habitat structure strongly influenced three flock variables (open-forest species per flock, total and rain-forest individuals per flock) and flock composition to a lesser extent. Finally, flock encounter rate was strongly related to fragment area, but not to abundance of flock participants indicating habitat degradation-induced changes in propensities of species to flock.

Item Type:	Journal Article
Publication:	Journal of Tropical Ecology
Publisher:	Cambridge University Press
Additional Information:	Copyright of this article belongs to Cambridge University Press.
Keywords:	Avian community ecology;habitat degradation;interspecific interactions;mixed-species flocks;tropical rain forests;Western Ghats.
Department/Centre:	Division of Biological Sciences > Centre for Ecological Sciences
Date Deposited:	11 Sep 2008 04:31
Last Modified:	19 Sep 2010 04:49
URI:	http://eprints.iisc.ac.in/id/eprint/15718

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