Community structure of waterbirds in Thadduvankoddy, Kapputhu and Nagarkovil in the Northern region of Sri Lanka.

Abstract

Waterbirds use many kind of coastal wetlands including swamps, lagoons, estuaries, bays, mudflats and open beaches. The present study was conducted to assess the community structure of waterbird families in Thadduvankoddy, Kapputhu and Nagarkovil in Jaffna Peninsula. Three counting blocks in length of 500 m with open width was selected in each site and counting of birds was done once a month from December, 2016 to November, 2017. A total of 67 waterbird species representing 19 families were recorded in three sites (55 species in Thadduvankoddy, 59 in Kapputhu and 51 in Nagarkovil. The highest measures of species richness (59), mean density of waterbirds ±SE(24.72±3.33birds km-2), Shannon Wiener diversity (2.91), Pielou’s evenness (0.72), Margalef richness (6.15) and Berger Parker dominance (0.27) indices were recorded in Kapputhu.Flamingos were the most dominant group of birds in all three sites (32.65%, 27.30 % and 29.05 % in Thadduvankoddy, Kapputhu and Nagarkovil respectively, followed by migrant ducks in Thadduvankoddy (30.54 %) and in Kapputhu (17.07). Cormorants and darters were the dominant group of birds followed byflamingos in Nagarkovil. The two-way ANOVA revealed that the abundance of waterbirds significantly varied temporally among different months (p=0.05) in the three sites. That might be due to the migration of waterbirds and the availability of water. The difference in waterbird species composition and the diversity indices could be due to the variation in habitat heterogeneity, availability of food and water resources. Thadduvankoddy provided habitat for wide array of waterbirds from October to March, 2017. Flamingos and ducks were the most dominant groups of birds in Thadduvankoddy. However, the site in Thadduvankoddygot completely dry from April to August, 2017 andit was a seasonal wetland during the rainy season. The availability of sufficient water level throughout the year makesKapputhu, an excellent habitat for wide variety of waterbirds especially flamingos and ducks. However, Thadduvankoddy got completely dry during dry season. Comparatively deeper water (>1 m) and dense mangroves in Nagarkovil provided suitable habitats for cormorants and darters for feeding and roosting. However, the drop in water level during dry season made the habitat suitable for wide array of waterbirds including flamingos. Thus, the findings revealed that the community structure of waterbirds depends on temporal variation of water level and availability of sufficient water.