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Surveys Recorded 1,258 Active River Tern Nests at Bhadra, Described as India’s Largest Known Colony

Sterna aurantia courting at Bhadra Reservoir, Karnataka, India
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A 2026 study at Bhadra Reservoir in Karnataka reports what the authors describe as India’s largest known breeding colony of river terns (Sterna aurantia). Across surveys of three reservoir islands from January to August 2023, researchers recorded 3,927 birds and 1,258 active nests.

Island 3 had the largest share of recorded nests

The largest concentration was on Island 3, where 652 active nests were recorded — just over half of the 1,258 nests reported across the three islands. Island 1 had 349 nests and Island 2 had 257. River tern numbers peaked in March and April during the breeding period.

The study was designed to estimate colony size and examine factors influencing the number of breeding birds using the reservoir islands. The authors present the counts as new information on the breeding ecology of river terns and as a basis for conservation of this large colony at Bhadra Reservoir.

Sources and image credit

  1. Karthik, N. J., Vijaya Kumara, & Sathiya Selvam. (2026). Estimating the Breeding Colony Size of River Tern (Sterna aurantia) in Bhadra Reservoir: Assessing India’s Largest Colony. Ecology, Environment and Conservation, 32(2), 810–814. https://doi.org/10.53550/EEC.2026.v32i02.056Primary peer-reviewed study in volume 32(2), the journal's June 2026 issue. The publisher lists the article in the issue and independent indexing records articles from volume 32(2) as published 14 June 2026. Surveys from January to August 2023 recorded 3,927 River Terns and 1,258 active nests across three islands in Bhadra Reservoir.

Image: Kandukuru Nagarjun / Wikimedia Commons — river terns courting on a breeding island at Bhadra Reservoir, Karnataka, India, 4 April 2021. Representative image for this story; not presented as an animal or scene from the reported study or event. · CC BY 2.0 · Source

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