Wintering birds: 170 birds
Family: Gulls, terns & skimmers
Glaucous gulls in breeding plumage have a pale grey mantel and wings, with white tips on their flight feathers. The underparts are white with some streaks on the upper breast. The tail is white.
They have white heads and a yellow bill with a red gonydeal spot. The eyes are light yellow surrounded by an orange eye-ring, and the legs and webbed feet are pink.
Out of breeding plumage they have brown streaks and mottles on the head and nape. Female are similar to males but slightly smaller.
Juvenile glaucous gulls have a scale pattern on their upperparts with buff edges to their feathers. The wing tips are white to pale brown, and they have pale brown underparts. The bill is pink with a black tip, and the eyes are dark brown.
By the second winter the glaucous gull has pale eyes and the plumage is more uniform. In the third winter they are similar to adults but there are still some brown patches on the wing and tail. There is a black spot gonydeal spot on the lower mandible.
Glaucous gulls breed in May and June in solitary pairs or loose colonies. They may also join other groups of seabirds. Both adults build the nest which is situated on the edge of a cliff or on sloping ground, on rock or even snow or ice. It is made from seaweed and grass and lined with softer grass.
Glaucous gulls lay 2-3 brown eggs with darker brown marks, which are incubated by the female and male for 27-30 days. Chicks are covered in pale grey down with dark markings. They are fed by both parents and leave the nest a few days after hatching. They can fly at 45-50 days and are independent by September. They are sexually mature at 4 years old.
Glaucous gulls eat a wide variety of food including fish, rodents, eggs and chicks, marine invertebrates, molluscs, and crustaceans, as well as seeds, grains and berries.
They may also eat the faeces of marine mammals and feed on their carcasses, and they follow trawlers for offal.
Glaucous gulls can be seen in the UK between November and April. They are found along coasts on beaches, harbours, and bays. They can also be spotted inland at landfills and reservoirs where they gather in large flocks with other gulls.
Glaucous gulls are active predators and kleptoparasites. They have been observed raiding the dens of arctic foxes to steal their cache of prey.