During migration, many shorebird species stage in the Wadden Sea to forage on the tidal flats before continuing the journey. As mudflats subside during high tide, a trade-off exists between quality of foraging grounds and proximity of roosts, where shorebirds rest during high tide. However, little is known about the space use of many shorebird species, including the most abundant in the Wadden Sea, the dunlin Calidris alpina. Here we determine how foraging and roost site choice is related to prey availability and water level. Using high-resolution tracking data and data on benthic prey densities, we analysed whether dunlins select foraging areas with high abundances of certain prey and if there is a relationship between water level, roost choice, and use of foraging ground. We found that dunlins forage on locations with high abundances of Hediste diversicolor and show seasonal selection for Peringia ulvae. Moreover, dunlins usually roost close to their foraging grounds, unless for higher water levels when they switch to a higher open roost further away. Our results increase the understanding of the mechanisms behind dunlin’s space use, which could help infer its response to threats like habitat loss and decreasing prey availability through sea level rise.
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