The Black-backed Gull is the largest gull in New Zealand.  In the adult, the head, neck, underparts, rump and tail are white, the back and upper wings are black with a narrow white trailing edge.  The bill is yellow with a red spot at the tip of the lower bill.  The eye is pale yellow and the legs greenish yellow.  First year birds are brown and in the second year the back is brown and the breast and neck are white flecked with brown.  By the third year the back and upper wings are brown and black.  There is a large variety of calls but the most characteristic calls are a contagious “uhuh, eeah – ha –ha –ha –ha –ha” or “kaloo, kaloo, kloo, kloo, kloo, kloo” heard in breeding colonies or feeding flocks, and a non – contagious “gorah, gorah” call mainly from breeding adults.

Black-backed Gulls are opportunists taking a wide variety of foods, including offal, refuse, carrion, marine invertebrates, shellfish, fish, eggs frogs, lizards, birds, mammals, small fruit and other plant material. 

Breeding is between mid October to late January in large colonies near the sea shore.  Some nest solitarily on coastal rock stacks and headlands, mountainsides and roofs of city buildings.  The nest built mainly by the male is a substantial mound composed of dry grass, seaweed, twigs and feathers which has a small but deep depression in the centre.  The clutch of 2 – 3 brownish or grey eggs with dark blotches is incubated by both parents for 23 -30 days.  The chicks fledge at 50 days and remain with their parents for at least a couple of months after fledging.

Pairs of Black-backed Gulls breed on Tiri.

Photography by: Max McRae © (adult on left, juvenile black backed gull on right)

References: Heather, B.D.; Robertson, H.A. 2000 The Field Guide to the Birds of New Zealand. Auckland, Viking.
Moon, G The Reed Field Guide to New Zealand Birds.