© S. Nuttall

© S. Nuttall

Hybrids between Mediterranean Gull and Black-headed Gull are sometimes encountered, perhaps occurring more frequently where Med Gull is expanding its breeding range into areas where Black-headed Gulls are already established. The juvenile in the photos above was photographed and diagnosed by Steve Nuttall at Belvide Reservoir during August 2015. As rest it looks much like a juvenile Med Gull in terms of plumage but the head and bill profile are too delicate (c.f. the adult Black-headed Gull alongside). The spread wing revealed in the lower photo is again closer to Med Gull than Black-headed Gull but note prominence of white on outer primaries and on outer alula.