Chatham oystercatcher

Nationally Critical (NZ TCS)
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Charadriiformes
Family: Haematopodidae
Genus: Haematopus
Species:
H. chathamensis
Binomial name
Haematopus chathamensis
Hartert, 1927

The Chatham oystercatcher or Chatham Island oystercatcher (Haematopus chathamensis) is a species of oystercatcher. It is a wading bird endemic to the Chatham Islands, New Zealand. 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 red and the eyes have orange orbital rings. The short, thick legs are pink. Adults are about 48 centimetres (19 in) in length.[2]

Distribution

The Chatham oystercatcher is only found on the Chatham Islands, an archipelago about 680 kilometres (420 mi) south east of New Zealand. Each of the four main islands has small breeding populations.

Behaviour

Image of Haematopus chathamensis eggs from the collection of Auckland Museum
Haematopus chathamensis eggs from the collection of Auckland Museum

The Chatham oystercatcher feeds on molluscs and marine worms, 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).[3]

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.[3] Juvenile birds become mature at about three years of age, and the lifespan is about eight years.[4] The success rate of each pair averages 0.44 fledglings per breeding season, with flooding the main cause of egg loss.[3]

Status

In the late 1980s, the total population was less than 110 birds, and was feared to be declining.[3] 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", and the Department of Conservation as "Nationally Critical".[5] The main threats faced by this bird are predation, particularly by feral cats on eggs and chicks, and the cattle and sheep which roam onto the beaches and may trample the nests. The introduced flightless weka (Gallirallus australis) is also a nest predator.[4]

References

  1. ↑ BirdLife International (2017). "Haematopus chathamensis". IUCN Red List of Threatened Species. 2017: e.T22693656A118496303. doi:10.2305/IUCN.UK.2017-3.RLTS.T22693656A118496303.en. Retrieved 13 November 2021.
  2. ↑ Hockey, P.A.R. (1996). "Family Haematopodidae (Oystercatchers)". In del Hoyo, J.; Elliott, A.; Sargatal, J. (eds.). Handbook of the Birds of the World. Vol. 3: Hoatzin to Auks. Barcelona, Spain: Lynx Edicions. pp. 308-325 [324]. ISBN 978-84-87334-20-7.
  3. 1 2 3 4 Schmechel, F.; Paterson, Adrian M. (2005). Habitat selection and breeding ecology of the endangered Chatham Island oystercatcher (Haematopus chathamensis) (Report). Wellington: Department of Conservation. hdl:10182/1640. ISBN 0-478-22683-7.
  4. 1 2 Moore, P.J. (2014). "Conservation assessment of the Chatham Island Oystercatcher Haematopus chathamensis" (PDF). International Wader Studies. 20: 23–32.
  5. ↑ "Haematopus chathamensis". NZTCS. 2016. Retrieved 2019-12-15.
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