Abstract:
Mixed-species bird flocks are attractive models for the
investigation of geographical variation in animal communities,
as they represent a subset of the avifauna in
most forested regions of the world. Yet studies of the
regional variation in flock size and the composition of
flocks are few, due to the predominance of studies
carried out at single study site. Here, we review nine
studies of mixed-species flocks conducted at 16 sites
along the Western Ghats in India and in Sri Lanka.
We find that flock size varies as much within this
region as it does globally, with observation time being
a confounding variable. Flock composition, however,
is predictably related to elevation. Flocks at high elevations
(>1200 m) in the Western Ghats strongly resemble
flocks at high elevations in the mountain
ranges of Sri Lanka in their composition, especially at
the family level. We compare these flocks to flocks of
other regions and make recommendations on study
methodology that can facilitate comparisons across
studies.
