The Red-billed Gull (Chroicocephalus scopulinus), also known locally as Mackerel Gull, is a native of New Zealand, being found throughout the country and on outlying islands including the Chatham Islands, where it is known as Jackie, and Sub-antarctic islands.The M?ori name of this species is Tarapunga. Its vernacular name is sometimes also used for the Dolphin Gull, a somewhat similar-looking but unrelated species. As is the case with many gulls, the Red-billed Gull has traditionally been placed in the genus Larus.
The Red-billed Gull is a fairly small gull with an all-red bill, red legs and feet, pale grey wings, and black wingtips. There is virtually no sexual dimorphism. It is the smallest gull commonly seen in New Zealand; a recent estimate of the population puts it at half a million birds in the country. Until recently it was regarded as a subspecies of the Silver Gull L. novaehollandiae found in Australia, and the two species are very similar in appearance. However the most recent research suggests that they are not particularly closely related.
Behaviorally, the Red-Billed gull is a typical gull. It is an aggressive scavenger and kleptoparasite. Large numbers now live in towns and cities (most New Zealand cities are coastal or nearly so), feeding out of rubbish bins. Nesting is in large colonies; the birds form pair bonds which endure across seasons, but there is a certain amount of extra-pair copulation. Courtship feeding is an important part of the preparation for mating.