Effect of Habitat Alteration on the Avian Inhabitants of a Water Body with Special Reference to Dendrocygna javanica

Wetlands are one of the most threatened habitats due to their vulnerability and scope for their inclusion in developmental changes and urbanization process. They provide home for a variety of wildlife. The study area is a 2.5 acre water body situated within the heart of Thrissur city. Large number of birds was seen in the water body from the months of September to February. Fourteen species of aquatic birds belonging to 7 different families were identified in Vadakkechira with 35.71% being common and 35.71% uncommon. Abundant and rare species comprised 7.14% and 21.43% respectively. 57.14% were resident to the area, 35.71% were local migrants and 7.14% were long distance migrants. The dominant species was Dendrocygna javanica. A downward trend in the number of birds was noticed during the period 2002 to 2012. The pond became infested with Salvinia indicative of enriched nutrient loading in the water body. Reduced levels of dissolved Oxygen and reduced pH were recorded in 2012. Increase in the level of CO2 and temperature was noticed during the period. Recreational activities and even the presence of large number of birds in previous years and altered land use might have contributed to the modification of this habitat, resulting in the decline of bird population.