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Common Redshank Food Intake Rate Fell as Nephtys Worms Became More Abundant

Common Redshank feeding in shallow water in Paradeniz Lagoon, Turkey
Research · Ecology

Common redshank (Tringa totanus) food intake rate fell as the polychaete worm Nephtys hombergii became more abundant, according to a 2026 re-analysis of classic field observations from 16 estuarine mudflats in southern England and South Wales. The data were collected during the winters of 1969–70, 1970–71 and 1971–72 and originally formed the basis of a 1977 model asking whether redshanks selected prey sizes that maximised how much food they obtained per unit of foraging time.

The new analysis accounted for season, tidal stage, ambient temperature and the birds’ social behaviour. Several relationships changed, and one central assumption of the original model was not supported: the two worms Hediste diversicolor and Nephtys hombergii could not be treated as a single combined food supply. The authors also note that Hediste is a well-established redshank prey, whereas there is little direct evidence that redshanks regularly eat Nephtys.

The two worms had opposite relationships with food intake

With Hediste, intake rate increased as worm density increased. With Nephtys, the relationship ran in the opposite direction: intake rate decreased as more Nephtys were present. Nephtys is itself a predator of Hediste, so the abundance of one worm may influence how available the other is to feeding redshanks.

A deeper-burrow explanation remains untested

The authors hypothesise that Hediste may avoid predatory Nephtys by moving deeper into their burrows. Below about 5 cm they would be beyond the reach of a redshank’s roughly 4 cm bill. This mechanism was not tested directly, and the researchers also could not rule out unknown sediment differences that might both favour Nephtys and make Hediste less accessible. The re-analysis therefore changes the biological interpretation of a classic foraging dataset without showing exactly which mechanism caused the pattern.

Sources and image credit

  1. Goss-Custard, J. D., Whitt, N. H., Goss-Custard, E. J., & Stillman, R. (2026). Foraging by Common Redshanks Tringa totanus on the polychaete worms Hediste diversicolor and Nephtys hombergii: A re-analysis of data first published in 1977. Ardea, 114(1), 1–14. https://doi.org/10.5253/arde.2026.a3Primary 2026 research article. The published version re-analyses field data collected from Common Redshanks foraging on 16 mudflats during the winters 1969–70 to 1971–72, incorporating environmental variables not included in the original 1977 model.

Image: Common redshank (Tringa totanus) feeding in Paradeniz Lagoon, Göksu Delta, Turkey, 11 December 2016. Photo: Zeynel Cebeci / Wikimedia Commons; cropped to 16:9. Representative feeding image; not a bird or site from the reported study. · CC BY-SA 4.0 · Source

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