Temporal Dynamics and Establishment of Breeding Colony of Eurasian Spoonbill (Platalea leucorodia) at Therthangal Bird Sanctuary, Tamil Nadu, India

Repeated monitoring of colonial waterbirds provides important insights into breeding habitat quality, colony persistence, and ecological stability. We assessed the breeding dynamics of the Eurasian Spoonbill (Platalea leucorodia) at Therthangal Bird Sanctuary (TBS), Tamil Nadu, India, using data from six breeding seasons (2019–2020 to 2025–2026), excluding 2020–2021 because of COVID-19 restrictions. Breeding chronology and reproductive performance were evaluated through monthly surveys from September to February. Courtship began in September, with nest building concentrated in October and peak nesting in November; hatching occurred during December, while fledging extended into January–February. Peak abundance reached 42 individuals in 2022–2023. Peak nest abundance increased from three nests in 2019–2020 to 12 in both 2022–2023 and 2025–2026. A notable finding of the study was the complete breeding failure during 2023–2024. Mann–Kendall tests detected no significant temporal trends in annual peak bird abundance or active nest abundance. Clutch size and nest-level hatching success did not differ significantly among breeding seasons (Kruskal–Wallis p > 0.05). Colony-level hatching success ranged from 68.4% (2021–2022) to 85.7% (2024–2025). Nesting occurred predominantly on Acacia nilotica, with limited use of Neltuma juliflora as a nesting substrate. Overall, our findings establish TBS as a regular breeding site for Eurasian Spoonbill in southeastern India. Sustaining this emerging breeding colony will require maintaining seasonal water hydrology, protecting suitable nesting trees, and minimizing disturbances during breeding seasons through locally compatible wetland management.