157668 Black-headed Gull - Chroicocephalus ridibundus - summer adult. L 35-38cm. Our most numerous medium-sized gull. Plumage variable but white leading edge to outerwings is consistent feature. Forms single-species flocks. Sexes are similar. Adult in summer has grey back and upperwings, white underparts and chocolate-brown hood. Legs and bill are red. In flight, trailing edge of outerwing is black. In winter, loses dark hood; white head has dark smudges above behind eye. Juvenile has orange-brown flush to upperparts, dark feathers on back, dark smudges on head, and dark tip to tail. Acquires adult plumage by 2nd winter through successive moults. 1st winter bird retains many juvenile plumage details but loses rufous elements and gains grey back. 1st summer bird still has juvenile-type wing pattern but gains dark hood. Voice Raucous calls include a nasal kaurrr. Status Widespread and numerous. Commonest on coasts and inland freshwater sites, but also in towns and on farmland; often follows the plough. Nests colonially beside water. Migrants from Europe boost winter numbers.