Knot Calidris canutus (see pictures below)
Standing knowledge is that Knots wintering in NW Europe belong to the Greenland race islandica. Adult birds return after breeding to NW Europe from the end of July onwards and undergo a complete moult in the months that follow. Juveniles arrive from the latter part of August onwards. The Wadden Sea in The Netherlands and Germany is of crucial importance for this population. Greenland Knots especially have suffered greatly from mechanical Cockle fisheries which is now largely forbidden. Greenland Knots leave Holland in the 2nd half of April when still in winter plumage. Nominate canutus , the Siberian Knot, breeds in Russia on the Taimyr peninsula and winters in West Africa, in particular on the Banc d’Arguin in Mauritania. These birds use the Wadden sea as a staging area on the way to or back from Taimyr to ‘refuel’ used up fat supplies during May and August. When they arrive in spring they are already in breeding plumage.
Knots Calidris canutus in 1st summer plumage
The Knots wintering in the Rhine-Meuse delta in the netherlands belong to the Greenland-race islandica. By the end of April they have left or are about to leave for the breeding grounds save for a small number of 2nd calendar year birds. These young birds begin moulting their worn 1st winter plumage into their 2nd winter plumage as can be seen on the pictures below.