Assessment of waterbird composition in Kalkundamaduwewa tank at Vavuniya, Sri Lanka

Abstract

Changes in abundance of waterbirds reflect the habitat changes of a tank ecosystem. Ephemeral tanks in Vavuniya district are known as habitats for rich birds diversity during different periods of a year. A short-term field study was made to assess the pattern of waterbird distribution at Kalkundamaduwewa tank during June to August of the year 2015. Visual observations were made twice a week at predefined sampling blocks of the tank. Standard methods were employed to count and identify the species of waterbirds. Data obtained were subjected to compute Species richness index, Shannon-Wiener index, Species evenness, Simpson’s diversity index, and Species similarity. Results suggest that the study tank had species diversity and abundance attributable to a wide variety of habitat along the water body. Nearly 94% of the encountered birds belonged to only eight species out of the total 15 recorded bird species. No significant influence in the bird counts for the rainfall and ambient temperature during the study period. Higher number of waterbirds were encountered in the blocks with higher vegetation. The high correlation of vegetation with the Species evenness and Shannon index justifies the species abundance in the tank. The investigation shows that the tank should be maintained for the birds’ conservation.