Phylum Chordata Family Laridae Scientific name Chroicocephalus bulleri Rank Species | ||
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Similar Gulls, Bird, Red‑billed gull, Hartlaub's gull, Black‑fronted tern | ||
Black backed gulls raiding nesting colony of black billed gulls
The black-billed gull (Chroicocephalus bulleri), also known as Buller's gull, is a species of gull in the family Laridae. It is found only in New Zealand.
Contents
- Black backed gulls raiding nesting colony of black billed gulls
- Taxonomy
- Description
- Distribution and habitat
- Status
- Important Bird Areas
- References
Taxonomy
As is the case with many gulls, it has traditionally been placed in the genus Larus, but is now considered to belong within the genus Chroicocephalus. The holotype is in the collection of the Museum of New Zealand Te Papa Tongarewa.
Description
The black-billed gull is a lightly coloured gull with a small amount of black on its wingtips. It has a long, thin, black bill with a bright red interior, and reddish black feet and white eyes. The juvenile has a flesh coloured bill with a dark tip and dark brown eyes. As juvenile red-billed gulls display similarly dark bills and feet they may be confused with this species.
Distribution and habitat
The black-billed gull is endemic to New Zealand. Its natural habitats are rivers, freshwater lakes, freshwater marshes, sandy shores, pastureland, and urban areas. It is threatened by habitat loss. About 78% of the population breeds in the Southland Region on the southern end of South Island, New Zealand, especially beside the Mataura, the Oreti, the Aparima and Waiau Rivers. On the North Island, breeding sites are typically sand-spits, shell banks, lake margins and river flats. It feeds on fish, terrestrial, freshwater and marine invertebrates and visits farmland and refuse tips.
Status
The black-billed gull has shown a marked decline in numbers since about 1980. A census in 1996 showed 48,000 nests which would equate to about 96,000 mature individuals. The bird faces threats from various predators that eat eggs and chicks. These include brown rats, weasels, hedgehogs and feral cats. Nesting colonies are disturbed by people and river modification through dredging or abstraction of gravel and water also impact on them. For these reasons, the IUCN has rated the species as being "Endangered".
Important Bird Areas
Sites identified by BirdLife International as being important for black-billed gull conservation are:
