Diversity and Abundance of Wetland Birds in Udayamarthandapuram Bird Sanctuary, Tiruvarur District, Tamil Nadu, India

Wetland birds are integral components of wetland ecosystems, providing ecological, economic, cultural, and regulatory benefits. The study conducted from 2021 to 2024 in the Udayamarthandapuram Bird Sanctuary of Tiruvarur district aimed to assess year-wise species diversity, richness, relative diversity, evenness, density, and relative abundance of wetland birds employing the total count method to estimate the population of wetland birds. A total of 104 bird species belonging 18 orders and 49 families were recorded. During this study, 17 species were migrant, while the remaining 87 birds were resident. Three bird species were classified as Near Threatened, including the Spot-billed Pelican (Pelecanus philippensis), Black-headed Ibis (Threskiornis melanosephalus), and Oriental Darter (Anhinga melanogaster). Additionally, two bird species were classified as Vulnerable, namely the Greater Spotted Eagle (Clanga clanga) and River Tern (Sterna hirundo), while 99 bird species were classified as Least Concern. Regarding species diversity in the Udayamarthandapuram Bird Sanctuary during different years, the highest species diversity was recorded in 2021 (2.75), while the lowest species diversity was observed in 2024 (1.64). In terms of species richness, the maximum richness was observed in 2023 (68), whereas the minimum species richness was recorded in 2022 (29).