Factors affecting the avi-faunal distribution in the three lagoons (Malala, Embillakala and Bundala Lewaya) of Bundala National Park (A Ramsar Wetland) in Sri Lanka

Abstract

Bundala National Park, covering an area of 6216 ha, is located about 250 Km Southeast of Colombo, in the Hambantota District. The shallow brackish water lagoons located within the park - Koholankala (390 ha), Malala (650 ha), Embilikala (430 ha) and Bundala (520 ha) form a complex wetland system that harbors a rich bird life, including several species of migratory waterfowl. This led to the declaration of Bundala as Sri Lanka's first Ramsar wetland - a wetland of international importance especially for migratory waterfowl, in 1990. Distribution and the composition of the aquatic bird species inhabiting these lagoons with respect to the habitat characters are poorly understood. Present study was conducted (December, 2000-December, 2001) in Malala, Embillakala and Bundala Lewaya lagoons with the objective of investigating the relationship between some lagoon parameters (salinity, perimeter, area) and water bird abundance and diversity. Data were collected weekly basis. Bird abundance and the composition significantly differ among lagoons. This study revealed the most abundant bird groups in each lagoon. Highest aquatic bird diversity was recorded in Embillakala. This high diversity in Embillakala lagoon can be partly attributed to its moderate salinity, water depth and abundance of aquatic macrophytes. Lowest aquatic bird diversity was recorded in Bundala Lewaya. This study also revealed that salinity, aquatic macrophytes and lagoon area were key determinants of aquatic bird abundance. Although these lagoons are in the same landscape, they vary each other physically and chemically so that different bird communities might be supported.