The black-headed gull (Chroicocephalus ridibundus) is a small gull that breeds in much of Europe and Asia, and also in coastal eastern Canada. Most of the population is migratory and winters further south, but some birds reside in the milder westernmost areas of Europe. Some black-headed gulls also spend the winter in northeastern North America, where it was formerly known as the common black-headed gull. As is the case with many gulls, it was previously placed in the genus Larus.
|Adult summer plumage|
|Adult winter plumage
|Map of eBird reports of C. ridibundus Year-Round Range Summer Range Winter Range|
Larus ridibundus Linnaeus, 1766
This gull is 38–44 cm (15–17 in) long with a 94–105 cm (37–41 in) wingspan. In flight, the white leading edge to the wing is a good field mark. The summer adult has a chocolate-brown head (not black, although does look black from a distance), pale grey body, black tips to the primary wing feathers, and red bill and legs. The hood is lost in winter, leaving just 2 dark spots. Immature birds have a mottled pattern of brown spots over most of the body. It breeds in colonies in large reed beds or marshes, or on islands in lakes, nesting on the ground. Like most gulls, it is highly gregarious in winter, both when feeding or in evening roosts. It is not a pelagic species and is rarely seen at sea far from coasts.
The black-headed gull is a bold and opportunistic feeder. It eats insects, fish, seeds, worms, scraps, and carrion in towns, or invertebrates in ploughed fields with equal relish. It is a noisy species, especially in colonies, with a familiar "kree-ar" call. Its scientific name means laughing gull.
This species takes two years to reach maturity. First-year birds have a black terminal tail band, more dark areas in the wings, and, in summer, a less fully developed dark hood. Like most gulls, black-headed gulls are long-lived birds, with a maximum age of at least 32.9 years recorded in the wild, in addition to an anecdote now believed of dubious authenticity regarding a 63-year-old bird.
Observations on the behavior of black-headed gulls show that black-headed gulls individuals synchronize their activity with other black-headed gulls neighbors. Synchronization in black-headed gulls groups is dependent on the distance between the black-headed gulls members. 
- Butchart, S.; Symes, A. (2012). "Larus ridibundus". IUCN Red List of Threatened Species. 2012: e.T22694420A38851158. doi:10.2305/IUCN.UK.2012-1.RLTS.T22694420A38851158.en.
- Jobling, James A (2010). The Helm Dictionary of Scientific Bird Names. London: Christopher Helm. pp. 104, 171. ISBN 978-1-4081-2501-4.
- Peterson, R., Mountfort, G. and Hollom, P.A.D.1967. A Field Guide to the Birds of Britain and Europe. Collins
- "Longevity, ageing, and life history of Chroicocephalus ridibundus". The Animal Ageing and Longevity Database. Retrieved 27 September 2015.
- Attenborough, D. 1998. The Life of Birds. BBC ISBN 0563-38792-0
- Copping, Jasper (28 March 2009). "Top restaurants face shortage of seagull eggs". The Daily Telegraph. London.
- "Conservation (Natural Habitats&c" (PDF). Archived from the original (PDF) on 14 April 2010.
- Evans, Madeleine H. R., et al. “Black-Headed Gulls Synchronise Their Activity with Their Nearest Neighbours.” Scientific Reports, vol. 8, no. 1, 2018, doi:10.1038/s41598-018-28378-x.
|Wikimedia Commons has media related to Chroicocephalus ridibundus.|
|Wikispecies has information related to Chroicocephalus ridibundus|
|Look up black-headed gull in Wiktionary, the free dictionary.|
- Black-headed gull stamps from many countries at bird-stamps.org
- Ageing and sexing (PDF; 2.0 MB) by Javier Blasco-Zumeta & Gerd-Michael Heinze
- Feathers of Black-headed Gull (Larus ridibundus) at Ornithos.de
- BirdLife species factsheet for Larus ridibundus
- "Chroicocephalus ridibundus". Avibase.
- "Common black-headed gull media". Internet Bird Collection.
- Black-headed gull photo gallery at VIREO (Drexel University)
- Interactive range map of Larus ridibundus at IUCN Red List maps
- Audio recordings of Black-headed gull on Xeno-canto.
- Chroicocephalus ridibundus in the Flickr: Field Guide Birds of the World
- Black-headed gull media from ARKive