From the Global Flyway Ecology blog in the Netherlands:
Record numbers of Sanderlings on remote Wadden Sea island
Posted on August 2, 2017 by Team Piersma
Emma Penning reports that currently (1 August 2017) over 21,000 Sanderlings roost on the Wadden Sea islet Griend, on sand banks actively created to allow Griend to “wander” again. This is twice the Dutch wintering population (ca. 9,000), and as high as the British wintering population of 20,500 birds (Reneerkens et al. 2009). As much as 10.5% of the flyway population is now on Griend (van Roomen et al. 2015). A record number of Sanderling on a single roost!
Emma Penning from the Royal NIOZ, and a team of researchers of the University of Groningen and NIOZ, are currently working on the island to document the ecological and geomorphological consequences of the ‘Griend Repair project’ by the owner and manager Natuurmonumenten.
Griend is a small uninhabited island in the middle of the Dutch Wadden Sea. Natural erosion processes would make this type of islet “wander” through the Wadden Sea, but the protecting sand dyke created decades ago had washed away. In the summer of 2016, sand and shells have been resupplied so that natural processes can take their course again. At the same time vegetation cover on the island has been removed to ensure breeding habitat for terns and gulls. The new very low and 400 m wide sand bank protects against erosion from the west, and “feeds” the island with sand to stimulate growth at the north and south sides. This sand bar apparently is an attractive feature for Sanderling.
To investigate the effects of the recovery project, and to find out more about the natural functioning of this Wadden Sea island, an intensive four-year research project has started that will run until 2020. Tracking and tracing the movements of Sanderlings and documenting their diet is part of the program.
Already before the restoration, Griend was a central hub for Sanderlings foraging on the mudflats of the western Dutch Wadden Sea. We expected that they would continue to roost on Griend after the restoration, because the barren and open character of the new sand bank Griend would offer a safe place for Sanderlings. But this turn-out of >21,000 birds is more than we dared to hope for! Our brand new tracking data shows that indeed they use a variety of feeding locations throughout western Wadden Sea. More on that later.