Curious to understand more about oversummering waders in West Africa, we set out to count our study areas in Parc National Banc d’Arguin, Mauritania.
During counts between 9 and 15 July 2017, carried out by the GFN team consisting of Ahmed Medou, Ahmed Amarajeyat, Mohamed Camara, Jan van Dijk and Bob Loos, a total of almost 65,000 birds were counted at six sites near Iwik, Mauritania (see map).
During high tides, the islands of Arel, Nair and Zira were counted, together with the coast of Ebelk d’Aiznaya and part of the Baie d’Aoutief.
The highest numbers were recorded for Flamingo (13,800), Curlew Sandpiper (12,614!), Dunlin (7,758) and Bar-tailed Godwit (5,046). Surprisingly, only 1,357 Red Knots were counted.
The last census of oversummering waders in Banc d’Arguin dates back to June 1988 when the entire area was counted between 8 June and 3 July during a WIWO expedition.
Comparison of the results with 1988 is not yet possible because the results per counting area from 1988 are not yet available. However we know that in June 1988 on Arel 2,400 Sanderlings and 1,400 Curlew Sandpipers were counted. We arrived at 2,450 Sanderling, and a spectacular number of more than 10,000 Curlew Sandpipers!
As expected, the majority of the oversummering waders were “young” birds, born in the previous summer and now in their second calendar year.
We also collected more than 300 colour-ring re-sightings from, among others, Red Knots, Bar-tailed Godwits, Curlew Sandpipers, Whimbrels and Spoonbills (both the local breeding birds of the subspecies balsacii and birds from the Dutch breeding population that decided to oversummer). More about those birds next time!
For curious readers we included the count data below.
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.
Reneerkens, J., Benhoussa, A., Boland, H., Collier, M., Grond, K., Günther, K., Hallgrimsson, G.T., Hansen, J., Meissner, W., de Meulenaer, B., Ntiamoa-Baidu, Y., Piersma, T., Poot, M., van Roomen, M., Summers, R.W., Tomkovich, P.S. & Underhill, L.G. 2009. Sanderlings using African–Eurasian flyways: a review of current knowledge. Wader Study Group Bull. 116: 2–20.
van Roomen M., Nagy S., Foppen R., Dodman T., Citegetse G. & Ndiaye A. 2015. Status of coastal waterbird populations in the East Atlantic Flyway. With special attention to flyway populations making use of the Wadden Sea. Programme Rich Wadden Sea, Leeuwarden, The Netherlands, Sovon, Nijmegen, The Netherlands, Wetlands International, Wageningen, The Netherlands, BirdLife International, Cambridge, United Kingdom &, Common Wadden Sea Secretariat, Wilhelmshaven, Germany.
Today (17 April 2017, 7:00 and 8:45) from the seabird migration observation point at Westerslag on the island Texel (Netherlands) we observed 425 Bar-tailed Godwits migrating northward. The groups of 40-60 birds each flew against an adverse northern wind (4B).
Remarkably, on the previous day (same time, same spot) not a single migrating Bar-tailed Godwit has been seen! The wind was quite the same: NW (4B).
In the Mokbaai at the southeast point of the island Texel at high tide at least 96 resting Bar-tailed Godwits were observed today, whereas on the 15th only three birds were present.
Along Egmond aan Zee, another seabird migration observation point, in period of three hours no less than 2428 Bar-tailed Godwits got through in northern direction. All birds are presumed to be the subspecies taymyrensis, who winter in Africa mainly Mauritania, and use the Wadden Sea as staging site. They will stay here close to one month, to recuperate before they migrate to their breeding grounds in Siberia.
The West African-Siberian Connection, in which the Wadden Sea plays a vital part as necessary stepping-stone between wintering- and breeding grounds, a distance of approx. 8,000 kilometres!
And now we are waiting for the first sat-tagged bird returning to the Wadden Sea!!