Avifaunal Diversity and Water Quality Analysis of Urban Wetlands of Colombo, Sri Lanka

Abstract

The present study was carried out to determine the effect of water quality on the diversity and distribution of avifauna in urban wetlands. The bird aggregation and physical and chemical parameters of water bodies were assessed using standard field-based methods. The study recorded 67 bird species of 35 families. The bird population parameters were influenced by total dissolved solids, dissolved oxygen, salinity, and visibility. The Shannon-Wiener species diversity index (Hˊ) ranged between 0.99±0.05 -1.71±0.03. The density of aquatic birds and species richness ranged between 1677.45±137.2 -4990.09±151.3 birdskm-2 and 14.85±0.36 -22.07±0.68 respectively in the five wetlands studied. Shannon-Wiener diversity index (Hˊ) resulted in significant negative relationships with total dissolved solids (R 2 =0.716; p<0.05), and salinity (R 2 =0.919; p<0.01). Bird density was positively related with Secchi disk depth (R² = 0.457; p<0.05).Further, bird density negatively correlated with salinity (R² = 0.568; p<0.05) and total dissolved solids (BD = -0.003TDS + 3.903; R² = 0.566; p<0.05). The results of the principal component analysis indicated Secchi disk depth and dissolved oxygen were extremely influenced on Thalangama tank followed by Heen Ela marsh. For the wetland sites of Beddagana and Kiribathgoda, salinity and total dissolved solids were the extremely influential parameters, where Beddagana and Diyasaru Park had an influence from electrical conductivity on the variation of diversity, density, and species richness of the aquatic birds.