T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network


Gull (Black-billed) Chroicocephalus bulleri

Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Charadriiformes
Family: Laridae
Genus: Chroicocephalus
Species: C. bulleri
Binomial name: Chroicocephalus bulleri
Synonyms: Larus bulleri
Common names: Black-billed gull, Buller's gull

The black-billed gull (Chroicocephalus bulleri), also known as, is a species of gull in the Laridae family. It is found only in New Zealand.
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.

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". (Text thanks to Wikipedia).

  

Thanks to Wikipedia for text and information http://creativecommons.org/licenses/by-sa/3.0/