I drive the Afsluitdijk almost daily for work and last days it was obvious that Black Terns are arriving. A large part of the European population gathers along IJsselmeer/Afsluitdijk after breeding (and before they migrate South), and today I took my bike for a closer inspection. Highest numbers were present between Breezanddijk and Den Oever.
|Black Terns above the Afsluitdijk (statue of Lely in the background)|
Although the tern was already moulting towards winter plumage it was rather easy to pick out thanks to the pale upperwings and white rump.
From the underside it rather resembles a moulting Black Tern but note that the flight feathers are very pale (the primaries and secondaries).