Avifaunal diversity assessment and conservation significance of Therthangal Bird Sanctuary, Ramanathapuram, Tamil Nadu: insights about breeding waterbirds

The study offers a comprehensive avifaunal diversity assessment within the Therthangal Bird Sanctuary (TBS) in the Ramanathapuram District of Tamil Nadu, India which was carried out from January 2021 to March 2023 consisting of two breeding seasons. We recorded 96 bird species of 18 orders and 44 families. Family representations by species were: Ardeidae 10, Accipitridae and Rallidae six each, Anatidae five, Alcedinidae, Cuculidae, Columbidae, Threskiornithidae, and Cisticolidae four each. Four globally ‘Near Threatened’ species (IUCN Red List) were reported: Oriental Darter Anhinga melanogaster, Black-headed Ibis Threskiornis melanocephalus, Asian Woolly-necked Stork Ciconia episcopus, and Spot-billed Pelican Pelecanus philippensis. Observed frequencies of species classes were: common (n = 58, 60%), uncommon (n = 28, 29%), and rare (n = 10, 10%). A majority of species were residents (n = 83, 86%), followed by winter visitors (n = 12, 12.5%), and a single passage migrant (Rosy Starling Pastor roseus). Of conservation significance is the finding that 23 of 40 waterbird species recorded in TBS were breeding on site. Maximum numbers of birds and nests were recorded in year 2, presumed to be due to better rainfall and water availability. The findings underscore the importance of TBS in providing bird habitat, and emphasise the need for its conservation, particularly in safeguarding breeding waterbirds habitat. This study provides baseline data essential for the management plan for the forest department of long-term conservation strategies.