Fig. 1

Spring (blue) and autumn (brown) migration routes of satellite-tagged Grey Plovers marked on migration in the Lower Saxon Wadden Sea, Germany. The location of the Wadden Sea is highlighted by a large red dot. Grey dots represent Argos ‘best of duty cycle’ positions, and lines connect subsequent fixes. Dashed lines denote the spring and autumn migration routes of a 2nd calendar year bird; curved black dotted lines represent great circle routes between the Wadden Sea and breeding sites on Yamal (c. 3400 km, yellow highlighted) and Taimyr (c. 4000 km, orange highlighted) as well as between the Wadden Sea and a wintering site in Guinea Bissau (c. 5000 km; map: Mercator projection)