Comparative Study of Avifaunal Diversity and Abundance on the Two Arms of an Ox-Bow Lake, Motijheel, Murshidabad, West Bengal

Diversity of avifauna is one of the most important ecological indicators to evaluate the quality of habitats. Birds react very rapidly to any changes in their habitat. They respond to secondary changes resulting from primary causes. Wetlands are highly productive but ecologically fragile and liable to degradation and degeneration under the prevailing anthropogenic pressure which in turn affects the avian diversity around them. The present investigation is a comparative study of avifaunal diversity and abundance on the two arms of a famous ox-bow lake named Motijheel (24° 9'12'' to 24° 9'42'' North and 88° 16'33'' to 88° 15'13'' East) of Murshidabad district, West Bengal, India. The influence of urban development is compared between the two arms of the lake exposed to similar types of weather conditions but different human pressure in terms of species diversity and species composition. Eight wetland characteristics were found to be directly or indirectly affected by human activities. One arm is well managed due to composite commercial pisciculture but other arm has negligible human activity. There is no barrier in between these two arms. Although the climatic and geophysical conditions of both the wetlands are same, a total of 67 bird species were recorded from the arm with negligible human activity whereas the other arm of the ox-bow lake supported only 31 species. The relationship between habitat characteristics and community structure varied throughout the year, suggesting that the birds respond differently to habitat characteristics depending on the season. Winter migrant density and diversity is high in structurally more heterogeneous area. The availability of feeding and roosting habitat is very important to the migratory species. All these habitat characteristics become highly influenced by intense agricultural practices and other anthropogenic pressure surrounding the wetland. Monitoring wetland birds provides valuable information on the ecological health and status of wetlands.