The Chatham oystercatcher or Chatham Island oystercatcher (''Haematopus chathamensis'') is a species of

oystercatcher The oystercatchers are a group of waders forming the family Haematopodidae, which has a single genus, ''Haematopus''. They are found on coasts worldwide apart from the polar regions and some tropical regions of Africa and South East Asia. The ...

. It is a wading bird

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

to the

Chatham Islands The Chatham Islands ( ) (Moriori: ''Rēkohu'', 'Misty Sun'; mi, Wharekauri) are an archipelago in the Pacific Ocean about east of New Zealand's South Island. They are administered as part of New Zealand. The archipelago consists of about te ...

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

. This species is rated by the IUCN as endangered, and has a current population of 310 to 325 birds (2004 census). The main threat is from introduced predators.

Description

The Chatham oystercatcher has distinctive black and white plumage and a long, thick orange-red beak. The head, neck, breast, back, wings and tail are black. The lower underparts are white with an unclear demarcation on the breast. The irises are yellow and the eyes have orange orbital rings. The short, thick legs are pink. Adults are about in length.

Distribution

The Chatham oystercatcher is only found on the

, an

archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster, or collection of islands, or sometimes a sea containing a small number of scattered islands. Examples of archipelagos include: the Indonesian Arc ...

about south east of New Zealand. Each of the four main islands has small breeding populations.

Behaviour

The Chatham oystercatcher feeds on molluscs and

marine worms Any worm that lives in a marine environment is considered a marine worm. Marine worms are found in several different phyla, including the Platyhelminthes, Nematoda, Annelida (segmented worms), Chaetognatha, Hemichordata, and Phoronida. For a ...

, digging them out of the sand with its beak and hammering the shells to open them. They prefer foraging on coastline to lagoon shoreline, foraging mostly on intertidal rock platforms and sandy beaches (though some birds preferred pasture). The nest is built on the beach on sandy or rocky shores and consists of a simple scrape. Sometimes it is built among low vegetation and may be rather more elaborate. Two or three eggs are usually laid. Young birds left their birth territory about 33 days after fledging. Juvenile birds become mature at about three years of age, and the lifespan is about eight years. The success rate of each pair averages 0.44 fledglings per breeding season, with flooding the main cause of egg loss.

Status

In the late 1980s, the total population was less than 110 birds, and was feared to be declining. By 2006 the total population on the four Chatham Islands was estimated to be 310 to 360 individuals of which fewer than 250 were mature individuals. The population is believed to be stable; the IUCN rates the Chatham oystercatcher as "

Endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and in ...

", and the Department of Conservation as "Nationally Critical". The main threats faced by this bird are

predation Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

, particularly by feral cats on eggs and chicks, and the cattle and sheep which roam onto the beaches and may trample the nests. The flightless

weka The weka, also known as the Māori hen or woodhen (''Gallirallus australis'') is a flightless bird species of the rail family. It is endemic to New Zealand. It is the only extant member of the genus '' Gallirallus''. Four subspecies are recogni ...

(''Gallirallus australis)'' is also a nest predator.

References

External links

Department of Conservation page about the species
* {{Taxonbar, from=Q1068189 Haematopus Birds of the Chatham Islands Birds described in 1927 Endemic birds of New Zealand Taxa named by Ernst Hartert