Larus novaehollandiae scopulinus
Maori names: Tarapunga, akiaki
Red-billed gulls are small, handsome and abundant. Native to New Zealand, they are found in the North, South and Chatham Islands as well as on subantarctic islands. They were once thought to be a subspecies of Australia’s silver gull, which is very similar in appearance, but it is now known they are not especially closely related. In addition to red bills, they also have red legs and red eye rims. Males and females look alike, though males are slightly larger than females. Juveniles have dark bills and legs and easily can be confused with black-billed gulls.
With the exception of a population at Lake Rotorua, they are seldom found more than a few kilometres inland. They have a wide and varied diet which includes small fish, molluscs, crustaceans, plankton, marine invertebrates, earthworms, insects, rubbish, and pretty much anything else they can catch, scavenge or steal. They are known to engage in a behaviour called kleptoparasitism, which involves harassing other birds into dropping their food.
Between September and December, red-billed gulls form large breeding colonies on the coasts of both the North and South Islands adjacent to seas rich in plankton, fish and marine invertebrates. Red-billed gulls form pair bonds that can endure over many seasons, though interbreeding with third parties is common. Occasionally they even interbreed with black-billed gulls. These colonies can be densely populated and shared with other seabird species. Competition for nesting sites is fierce with eggs frequently becoming casualties in territorial squabbles. A nest is comprised of a mound of seaweed, grass, sticks and feathers with a small depression at the top. Clutch size is usually 2-3 eggs. Incubation is shared by both parents. Chicks fledge at 37 days old.
While most red-billed gulls live 6-14 years, they can potentially enjoy much longer lives. In 2009 a banded individual was found alive and well 28 years after it was banded.