The black-billed gull (Chroicocephalus bulleri), also known as Buller's gull, is a species of gull in the Laridae family. It is found only in New Zealand.
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.
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.
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
- "Larus bulleri; holotype". Collections Online. Museum of New Zealand Te Papa Tongarewa. Retrieved 17 July 2010.
- "Black-billed Gull factsheet". BirdLife data zone: Important Bird Areas. BirdLife International. 2012. Retrieved 2012-11-15.
- BirdLife International 2006. Larus bulleri. 2006 IUCN Red List of Threatened Species. Downloaded on 24 July 2007.
- Pons J.M., Hassanin, A., and Crochet P.A.(2005). Phylogenetic relationships within the Laridae (Charadriiformes: Aves) inferred from mitochondrial markers. Molecular phylogenetics and evolution 37(3):686-699
|Wikimedia Commons has media related to Chroicocephalus bulleri.|
- Department of Conservation New Zealand Teaching Resource - Threatened birds. Downloaded from http://www.doc.govt.nz on 11/05/2013