Composition of Mix Species Foraging Flocks of Birds in Riverstan of Montane Region, Sri Lanka

Montane zone mixed-species bird flock system is distinct from that of low-land wet zone of Sri Lanka, although some species are present in both systems. The present study identified the mixed species flocks of birds in Riverstan at Knuckles Region, Sri Lanka. Monthly transect counts and opportunistic observations were made between January and May, 2012. A total of 7 8 flocks and 27 bird species were encounter ed at Riverstan during the study period. The flock size varied between 2 to 13 species and 4 to 58 individuals. The mean number of species per flock was 6.03 ± 2.25 and the mean number of individuals in a flock was 18.41±9.87. The flock size was positively correlated with the number of species present (r = 0.756, P <0.05). Grey-headed Canary Flycatcher was the most abundant species (mean 2.68±1.02 birds per flocks) while Sri Lanka White-eye was the most frequent species (mean 5.69±3.92 birds per flocks). Grey-headed Canary Flycatcher and Sri Lanka Scimitar-babbler were the nuclear species in Riverstan. The leading species were Sri Lanka white-eye and Sri Lanka Yellow-eared Bulbul. Different bird species used different heights within flocks.