The black-headed gull (Chroicocephalus ridibundus) is a common, adaptable species across much of the Northern Hemisphere. It inhabits diverse landscapes, from coastal regions and estuaries to inland lakes and agricultural fields, and is recognizable in both rural and urban environments.
Physical Characteristics
The black-headed gull is a medium-sized gull, measuring between 38 to 44 centimeters (15 to 17 inches) in length with a wingspan ranging from 90 to 110 centimeters (35 to 43 inches). Its overall build is relatively slender compared to larger gull species. Its head plumage is its most distinctive feature, undergoing a seasonal transformation.
During the breeding season, in spring and summer, adults develop a prominent chocolate-brown hood that covers the entire head and extends slightly down the nape. This hood is bordered by a narrow white band, and the bill and legs are a deep red color. The back and upper wings are pale grey, contrasting with white underparts and distinctive black wingtips.
In winter, the dark hood recedes, leaving the head mostly white with two dark spots: one behind the eye and a smaller mark on the ear coverts. The bill and legs fade to a duller reddish-orange.
Habitat and Global Distribution
The black-headed gull has a wide distribution, breeding across Europe and Asia. They are highly adaptable, using diverse habitats for nesting and foraging. Preferred breeding grounds include coastal marshes, estuaries, and large inland wetlands.
Many populations migrate south for winter, reaching southern Europe, North Africa, the Middle East, and parts of Southeast Asia. During these non-breeding periods, they frequently gather in large flocks in agricultural fields, along riverbanks, and in urban parks.
Diet and Foraging Behavior
The diet of the black-headed gull is remarkably diverse, reflecting its opportunistic and omnivorous feeding habits. These birds consume a wide variety of food items, including terrestrial and aquatic invertebrates such as earthworms, insects, and crustaceans. Small fish, carrion, and discarded human food scraps also form a significant part of their diet, particularly in urban and agricultural settings.
They employ several foraging techniques to acquire food. Gulls often walk across fields, picking invertebrates from the surface, or follow farmers’ plows to feed on exposed worms and grubs. Over water, they frequently pick items directly from the surface while swimming or flying, and occasionally perform shallow plunge-dives to catch small fish. Their adaptability in finding food contributes to their success in various environments.
Nesting and Social Behavior
Black-headed gulls are well-known for their colonial nesting behavior, often forming large, dense aggregations that can number in the thousands of pairs. These noisy colonies are typically established in wetlands, on islands, or in areas with dense vegetation that offers some protection from predators. The collective nature of their breeding provides a measure of safety and facilitates social interactions.
Nests are generally simple structures, consisting of a shallow scrape on the ground lined with available plant material such as grasses, reeds, and twigs. The female typically lays a clutch of two to three olive-brown eggs, marked with darker spots. Both parents share the responsibilities of incubating the eggs and caring for the chicks once they hatch. The colonies are characterized by constant vocalizations, including their distinctive “laughing” calls, which contribute to the bustling atmosphere of their breeding grounds.