Study of Physico-chemical Parameters and Bird Diversity in Khajua Beel, a Freshwater Wetland of Udalguri District, Assam, India

Abstract

Wetlands provide habitat and feeding resources for resident and migratory birds, while their ecological condition is influenced by seasonal variation in water quality. This study documented selected physicochemical characteristics and avian diversity in Khajua Beel, a freshwater wetland in Udalguri District, Assam, from November 2024 to April 2025. Water temperature, pH, dissolved oxygen, biochemical oxygen demand, free carbon dioxide, total acidity, and total alkalinity were measured monthly. Bird surveys were conducted through walking surveys and point counts during morning and afternoon observation periods. Forty bird species representing 11 orders and 19 families were recorded, including 24 residents, 12 migratory species, and four local movers. Carnivorous birds constituted the largest feeding group, followed by omnivorous species. The recorded assemblage included one Endangered species and three Near Threatened species. The Shannon diversity, Simpson diversity, and Pielou evenness indices were 3.12, 0.93, and 0.89, respectively. Dissolved oxygen declined from 9.07 mg/L in November to 6.36 mg/L in April, whereas free carbon dioxide increased from 12.15 mg/L in December to 14.24 mg/L in April. Bird species richness was comparatively greater during winter and declined towards April. These observations provide a preliminary inventory of avian diversity and seasonal water characteristics at Khajua Beel and support the need for continued ecological monitoring.