BLACK-HEADED GULL (Chroicocephalus ridibundus) (See images below)
DESCRIPTION: The Black-headed Gull is a small ‘Old World’ gull. The head of this gull is actually dark brown in the summer for the adult. The upper parts are grey in the adult with black at the wing tips, and the under parts including the tail are white. The bill and legs are red to dark red. Sexes are similar. Juveniles have light brown upper parts instead of light grey, and a dark band at the tip of the tail. This gull is about 40 cm (16 inches) long.
NAME: The English name ‘Gull’ would have its origins in Old Celtic ‘Gullan’ and other languages, including Latin ‘gula’ for throat. As per Choate this would be related to the gull’s ‘indiscriminate’ scavenging habits, its ‘willingness to swallow almost anything’ (think ‘gullible’).
The Latin genus name ‘Chroicocophalus’ means ‘black head’. The Latin species name ‘ridibundus’ means ‘laughing’ (think of ‘ridiculous’), in reference to its call. However there is already another species of small gull with a black head, the Laughing Gull, which is a New World species.
HABITAT: Near the water along the coast and inland.
DIET: The black-headed gull is omnivorous and, as with many species of its family, an opportunistic feeder, i.e. will also feed on carrion.
NESTING: Black-headed gulls nest in colonies, and their nests are built on the ground. Usually two or three green-beige eggs are laid, which are incubated by both parents. They also both feed the chicks.
DISTRIBUTION: The breeding range of the black-headed gull encompasses Europe and Asia. Iceland colonies migrate to the Atlantic provinces for the winter. Some vagrants even showed up on Hawaii. (See note below on bird vagrancy.)
ON PEI:The black-headed gull is not known to breed on Prince Edward Island yet. Its sightings range from occasional to rare, depending on the seasons and the years.
CONSERVATION: This species is one of the most abundant gulls in the world, and it is not considered at risk.
NOTES: The eggs of this species are eaten as a delicacy in parts of Europe. Gulls have many plumages, from juveniles to breeding or non breeding adults (photo below), so their identification can be challenging.
Vagrancy: In biology this means an animal going way outside its normal range. For birds, this can happen when there are storms and they get blown off course. On other times, the bird simply wanders in a different direction than usual. Here’s an article about vagrancy in birds.
GULLS ON HAWAII: Gulls are not long time residents or indigenous to Hawaii. They are continental species and the Hawaiian Islands don’t seem to provide them with the habitat they need. Those birds that do make it however have either flown on their own or got blown off course, or hitched a ride on ships. In either case they don’t stay for long. 
SIMILAR SPECIES: Laughing Gull, Bonaparte’s Gull

Black-headed gulls in winter plumage Ueno Park, Tokyo, Japan - © Denise Motard
Black-headed gulls in winter plumage
Ueno Park, Tokyo, Japan
Black-headed gull in breeding plumage, with Greater flamingoes, Deltebre, Spain - by Roberta Palmer
Black-headed gull in breeding plumage with
Greater flamingoes - Deltebre, Spain, Roberta Palmer