DIVERSITY AND DISTRIBUTION OF BIRDS IN BHARATHAPUZHA RIVER BASIN, KERALA

Abstract

Bharathapuzha also known as the Nila River is the second-longest river in Kerala. It is considered as one of the most important rivers in Kerala for its ecological, cultural, and historical importance. Thus, it is known as the cradle of civilisation in Kerala. This river originates from the northern and southern rims of the Palakkad Gap. It flows towards the west through the Coimbatore district in Tamil Nadu and the Palakkad, Thrissur, and Malappuram, districts of Kerala before draining into the Arabian Sea. The river's total length is 209 km with a drainage area of 6186 km2. Chitturpuzha, Kalpathipuzha Gayathripuzha, and Thoothapuzha are major tributaries of this river. Birds are considered as indicators of habitat quality. They play an important role as predators, prey, pollinators and scavengers in nature. Understanding the natural bird assemblage, its patterns, and its process will help prioritize the potential conservation areas. Many researchers have attempted to study bird communities in the different habitats in the Western Ghats. Their observations on birds provided useful information to understand the distribution trend of birds. Most of such studies focused on the forest ecosystems in the protected area network. Understanding the distribution pattern of birds and their drivers in highly disturbed ecosystems outside the protected area network is less attempted. From the origin to the mouth, the river passes through various ecosystems and topographic conditions. Bharathapuzha originates and runs through forest ecosystems in the Western Ghats hill ranges initially, then travels through various human habitations, and agrarian lands and finally reaches the Arabian Sea. So, it supports bird communities of different forest ecosystems, agrarian lands, water bodies, and human habitations including the urban areas. Most of these ecosystems are located outside the protected area network and are vulnerable to anthropogenic pressures. Deforestation in the hill region, construction of check dams, indiscriminate sand mining, the spread of weeds and invasive plants inside the river channel, expansion of monoculture plantations, encroachment and water pollution are the major threats to the river ecosystem. This study attempted to understand the patterns of avifaunal assemblage in the Bharathapuzha river basin which is highly disturbed due to anthropogenic pressures that destroyed the riverine habitats, water quality, and natural water flow.