Gull the exceptions being Sabine's gull and swallow-tailed gulls, which have forked tails, and Ross's gull, which has a wedge-shaped tail. Gulls have moderately long legs, especially when compared to the similar terns, with fully webbed feet. The bill is generally heavy and slightly hooked, with the larger species having stouter bills than the smaller species. The bill colour is often yellow with a red spot for the larger white-headed species and red, dark red or black in the smaller species. The gulls are generalist feeders. Indeed, they are the least specialised of all the seabirds, and their morphology allows for
Black-tailed gull breeding grounds. The black-tailed gull feeds mainly on small fish, molluscs, crustaceans scraps and carrion. A study analyzing the identifiable parts of gull excreta in Korea found that 19.1% consisted of the remains of fish, 3.3% of crustaceans, and 3.3% of land insects. The species often follows ships and commercial fishing fleets. It also steals food from other seabirds. It is a colonial nester, with colonies forming in mid-April. 2–3 eggs are laid by early June. Incubation lasts approximately 24 days. Black-tailed gulls use a variety of voice signals and are known to use more than 10 different sounds for