Black-backed Gull/Dominican Gull

Maori Name: Karoro

Larus dominicanus

Maori name Karoro                                                                               

 

Also known as the Dominican Gull, the Black-backed Gull is familiar and widespread around NZ, as they are in other parts of the southern Hemisphere.  They are very good at adapting their diet to their environment, and anything indigestible will regurgitate as rounded pellets.  They are the largest and most heavily built of the New Zealand’s gulls. 

 

Most black-backed gulls nest in large colonies of up to several thousand pairs on coastal dunes, sand spits, boulder banks, gravel beaches, rocky islets, coast rock stacks and headlands, near mountain tarns up to 1500m above sea level, and even on roofs of city buildings. There are breeding colonies at many of the regions river mouths and notably at Millerton, Bucklands Peak and Mt. Davy which is the largest.  Numbers of birds at colonies start building up in late July and nest-building commences almost immediately.  The nest is mainly built by the male and is a large mound of dry grass, seaweed, twigs, feathers and tidal flotsam, with a small but deep depression in the centre.  Most eggs are laid between mid-October and late November, though some repeat clutches are laid through to late January.  The usual clutch of eggs is between one and three and they are laid 2-3 days apart.  Both parents incubate the eggs for 23 – 30 days and brood the nestlings for 2-3 days.  The chicks then leave the nest for increasingly longer periods, though usually one of the parents is with the chicks to guard them until they fledge at around 50 days old.  They remain with the parents for a couple of months after fledging.  Most birds do not start breeding until they are at least 4 years old and non-breeders form a ‘club’ at the edge of the breeding colony.

 

The black-backed gull is the largest and only black-backed gull, with the male larger than the female.  They have a yellow bill with a deep orange or red spot on the lower bill which is used as a ‘target’ for the chicks to peck at when being fed by the parents.

 

Black-backed gulls are common on most beaches, and over pasture in Spring.

 

The black–backed gull was once fully protected under the Wildlife act 1953. However this full protection was lifted in 1970.