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Coastal Stopover Dependence Best Predicted Which Shorebirds Declined in Bangladesh Counts

Common Greenshank in shallow wetland habitat
Conservation · Population & status

Fourteen years of standardized counts on Sonadia Island in Bangladesh showed downward population trends in 12 of 20 migratory shorebird species between 2009 and 2023. When the researchers compared migration strategies and life-history traits across species, the habitat used at migration stopovers was the clearest predictor of these differences: species that depend mainly on coastal stopover habitats tended to fare worse than those able to use inland routes.

Coastal-stopover specialists declined most often

Nine species were classified as coastal obligates during migration and 11 as non-coastal obligates. Seven of the nine coastal species showed statistically supported declines in the main analysis, compared with three of the 11 non-coastal species. The result therefore describes a strong difference in risk between migration strategies, not an absolute divide between declining coastal birds and secure inland migrants.

The exceptions are biologically important. Common greenshank (Tringa nebularia), Eurasian curlew (Numenius arquata) and curlew sandpiper (Calidris ferruginea) use inland stopovers but still declined significantly at the Bangladesh study site, by an estimated 16.4%, 13.6% and 12.3% per year respectively. Common redshank (Tringa totanus), Kentish plover (Anarhynchus alexandrinus) and the combined Red-necked Stint–Little Stint group, which included little stint (Calidris minuta), did not show a clear trend in the main analysis.

Researchers combined the Sonadia trends with satellite tracking and tested nine ecological and life-history characteristics. Across alternative analyses, migration stopover habitat was the most consistent predictor of why species differed in their trends. Reliance on the Yellow Sea also contributed to the pattern, but less consistently than the broader distinction between coastal and inland stopover use.

Inland migration routes also contain major conservation gaps

Tracking data showed that non-coastal migrants wintering in Bangladesh can cross the Himalayas and use inland stopovers rather than following the coast. On the Qinghai–Tibet Plateau, 64% of the identified inland stopover sites used by tracked birds lay outside protected areas, and inland sites were much less intensively monitored than coastal sites.

The authors therefore argue for attention to both sides of the result. The stronger declines among coastal specialists reinforce the importance of protecting coastal wetlands, while the poorly protected and poorly monitored inland stopovers remain essential to species that migrate across the Asian interior. The population-trend estimates in this study describe the birds counted at Sonadia; they should not be read as direct estimates of whole global populations.

Sources and image credit

  1. Chowdhury, S. U., Foysal, M., Khan, N. U., Choi, C.-Y., Qiu, W., Field, D. J., Clark, N., Green, R. E., & Balmford, A. (2026). Interspecific variation in shorebird population trends in relation to migration stopover habitat. Proceedings of the Royal Society B: Biological Sciences, 293(2071), 20260161. https://doi.org/10.1098/rspb.2026.0161Primary open-access research article published online 27 May 2026 under CC BY 4.0. Fourteen years of standardized counts from Sonadia Island, Bangladesh, were analysed for 20 migratory shorebird species and combined with satellite tracking and ecological and life-history variables. Twelve species declined; migration stopover habitat was the strongest predictor of interspecific variation in trends. Common Greenshank, Eurasian Curlew and Curlew Sandpiper showed significant declines of 16.4%, 13.6% and 12.3% per year respectively in the main negative-binomial model.

Image: Charles J. Sharp / Wikimedia Commons — adult Common Greenshank photographed at Standlake, Oxfordshire, United Kingdom, 30 July 2015; representative species image, not a bird from the Bangladesh study · CC BY-SA 4.0 · Source

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Population & status

SPECIES IN THIS STORY

Species in this story

Common Greenshank Tringa nebularia Explore species Eurasian Curlew Numenius arquata Explore species Curlew Sandpiper Calidris ferruginea Explore species Common Redshank Tringa totanus Explore species Kentish Plover Anarhynchus alexandrinus Explore species Little Stint Calidris minuta Explore species

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