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Nine Migratory Shorebirds Concentrated on a Prey-Rich Kerala Beach Despite High Predator Numbers

Common Greenshank in wetland habitat at Bhigwan, India
Research · Ecology

A nine-year study in Kadalundi–Vallikkunnu Community Reserve on the west coast of Kerala, India found that nine migratory shorebird species continued to concentrate most strongly on the reserve’s sand beach, where prey, shorebird and human-disturbance densities were highest. Predator density was also high there, although predator attack rates were lower on the beach than in the mangroves and mudflats.

The researchers compared mudflats, mangroves and sand beach habitat and examined how shorebird density and food intake responded to prey, predators, other shorebirds and disturbance. The nine focal species were Tibetan Sand Plover (Anarhynchus atrifrons), Greater Sand Plover (Charadrius leschenaultii), Pacific Golden Plover (Pluvialis fulva), Common Redshank (Tringa totanus), Common Greenshank (Tringa nebularia), Whimbrel (Numenius phaeopus), Eurasian Curlew (Numenius arquata), Terek Sandpiper (Xenus cinereus) and Sanderling (Calidris alba). Across all nine species, density increased with prey density and with the density of other shorebirds.

Predator effects varied among species

Predator effects varied among species. Common Greenshank, Eurasian Curlew, Greater Sand Plover and Pacific Golden Plover occurred at lower densities as predator density increased, while Whimbrel and Pacific Golden Plover also declined where predator attack rates were higher. Feeding responses were similarly species-specific: greater prey density increased intake rate in Common Greenshank and Sanderling, whereas higher predator density reduced intake in Eurasian Curlew, Greater Sand Plover and Whimbrel. The nine species therefore shared a strong attraction to prey-rich feeding grounds without responding uniformly to the risks present there.

Human disturbance also reshaped the food web

Human activities shaped the system indirectly as well as through disturbance. Disposal of poultry waste provided a persistent food subsidy for predators, contributing to exceptionally high predator densities and attack rates across the reserve. Even so, the sand beach remained the principal feeding area because it also offered abundant prey. The study did not measure direct lethal predation, but it documented non-lethal effects through reduced food intake in several species. The authors describe the system as one in which attractive feeding cues could create an ecological trap. They recommend eliminating or substantially reducing poultry-waste disposal, preferably beginning from May to August when migratory shorebirds are absent or scarce, because an abrupt reduction in subsidised food could initially shift predators toward natural prey.

Sources and image credit

  1. Aarif, K. M., Nefla, A., Musilova, Z., Musil, P., & Estrella, S. M. (2026). Spatio-temporal responses of a migratory shorebird community reflect complex trade-offs among overabundance of predators and disturbance. Ecological Solutions and Evidence, 7(1), e70199. https://doi.org/10.1002/2688-8319.70199Primary open-access research article first published 6 February 2026. Nine years of observations at Kadalundi–Vallikkunnu Community Reserve in Kerala compared densities and intake rates of nine migratory shorebird species across mudflats, mangroves and sand beach. All species concentrated most strongly at the prey-rich sand beach. Poultry-waste disposal subsidised predators, contributing to high predator densities and attack rates; Common Greenshank density decreased significantly with increasing predator density.

Image: Tisha Mukherjee / Wikimedia Commons — common greenshank (Tringa nebularia) at Bhigwan, Maharashtra, India, photographed 12 January 2026. Representative Indian species photograph, not from the Kadalundi–Vallikkunnu study site in Kerala. · CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ · Source

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Ecology

SPECIES IN THIS STORY

Species in this story

Common Greenshank Tringa nebularia Explore species Common Redshank Tringa totanus Explore species Eurasian Curlew Numenius arquata Explore species

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