26-5-2017 MARJAL DE MOROS, VALENCIA - BLACK HEADED GULL (Chroicocephalus ridibundus)

The black-headed gull (Chroicocephalus ridibundus) is a small, nimble gull with a wingspan ranging from 94 to 110 cm and a body length of 37 to 44 cm. It weighs between 190 and 400 grams. Despite its name, the adult's summer plumage features a chocolate-brown head, which can appear black from a distance. The body is pale grey, and the primary wing feathers are tipped with black. The bill and legs are a striking red. In winter, the brown head is replaced by a white one with dark spots. Juveniles are mottled with brown spots and have a black band on the tail. There is no sexual dimorphism in plumage.

In flight, the white leading edge of the wing is a distinctive field mark. The summer adult's brown head, red bill, and legs are key identifiers, while the winter plumage features two dark spots on the head. Juveniles can be recognized by their mottled brown pattern and black tail band.

This species nests in colonies on the ground in large reed beds, marshes, or islands within lakes. It is not pelagic and is seldom seen far from coasts.

The black-headed gull breeds across much of the Palearctic, including Europe and coastal eastern Canada. It is migratory, wintering further south, but some remain in the milder westernmost areas of Europe. It is also present in northeastern North America and occasionally seen as far south as Virginia and some Caribbean islands.

Highly gregarious in winter, the black-headed gull is an opportunistic feeder, consuming a wide range of food from insects to carrion. It is known for its "kree-ar" call and displays various behaviors such as eggshell removal from the nest, which is believed to reduce predation risk.

The black-headed gull is a vocal species, particularly in colonies. Its call is a familiar "kree-ar," and its scientific name suggests a laughing sound.

This gull takes two years to reach maturity. First-year birds can be distinguished by a black terminal tail band and a less developed dark hood in summer. Breeding occurs in colonies, and the species is known for its complex social behaviors, including begging coordination between siblings and conspecific brood parasitism.

The black-headed gull can be confused with the similar-looking Bonaparte's Gull in North America.

The diet includes insects, fish, seeds, worms, scraps, carrion, and invertebrates in ploughed fields. It feeds in towns and agricultural areas with equal relish.

The black-headed gull is listed as Least Concern on the IUCN Red List, indicating it is not currently at significant risk of widespread decline.

Individuals synchronize their vigilance activities with nearby conspecifics, depending on the distance between them.

The first recorded sighting in Australia occurred in 1991 at the Broome Sewage Ponds, marking a significant range expansion for the species.

The black-headed gull has been immortalized in Richard Adams' novel "Watership Down" as the character Kehaar and is the official bird of Tokyo, Japan.