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Black-backed gull  karoro

Why is it a problem?

A scavenging bird, the population of black-backed gulls | karoro has exploded as a direct result of human activities, primarily around garbage dumps, fish processing plants, and areas where effluent is discharged. While their numbers have declined somewhat in the past few years as rubbish disposal has been improved, like all scavengers, they are opportunistic predators that readily kill river bird chicks – see the videos below – and are increasingly implicated in the failure of entire breeding colonies of critically endangered endemic black-billed gulls and black-fronted terns.

black backed gull

Important: in spite of their size, they are sometimes mistaken for the endangered black-billed gull tarāpuka or red-billed gull tarāpunga. To avoid fines up to $300,000 for mistaken identity, any attempt to control black-backed gulls through shooting, trapping, poisoning, pricking eggs, or any other method,  should only be undertaken after consulting with ECan or DOC in your area.

Photo: Steve Attwood
Photo: Steve Attwood

Description

The Southern black-backed gull (Larus dominicans) karoro, (Maori), also known as the kelp gull, Dominican gull, mollyhawk, and seagull, is the largest gull and one of the most abundant large birds in New Zealand. It is also common in southern Australia, South America, southern Africa, most sub-antarctic Antarctic islands and the Antarctic Peninsula. Adults have white head and underparts with black back, yellow bill with red spot near tip of the lower mandible, and pale yellow-greenish legs. Juveniles are dark mottled brown with black bill and legs; their plumage lightens with age until they moult into adult plumage at 3 years old. Juveniles may be confused with the stockier brown skua.

Conservation activities

While Ngai Tahu regards it as a taonga species, the black-backed gull  | tarāpunga is one of only two native bird species not afforded any level of protection under the Wildlife Act. Black-backed gulls  | tarāpunga are often considered pests and on farmland, where some attack cast sheep and newborn lambs. As a result, they are sometimes shot, controlled using toxins, or by pricking their eggs. At a few sites, including the Waimakariri River and Hurunui River, they are controlled to reduce their predatory impacts on threatened birds.

The Canterbury Southern Black-backed Gull | Karoro management strategy outlines the rationale and recommendations for controlling the population.

More information

2024 Braided Rivers Seminar presentation: Local movements of colony-based karoro/Southern black-backed gull (PDF)

Further references and research