Biology
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Life span is on average 7.7 years (3), although the oldest recorded individual reached the age of 28 (2). The breeding season runs from October to March (4) and females start breeding from three years old (2). Nests are built in scrapes on the ground and two to three eggs are laid (2). The nests tend to be positioned on the shore away from the waterline, amongst low vegetation (3), or under an overhanging rock on the cliff edge (4). Individuals are territorial throughout the year (4).
The principal diet is made up of marine molluscs, worms and other invertebrates (3), which are prized from the rocks by the thick bill (4). Feeding on the rocky shore, oystercatchers have also been observed to feed on the anemone Isactina tenebrosa (4).
Conservation
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In 1998, the New Zealand Department of Conservation began an intensive oystercatcher management programme (3). Methods used to enhance the survival of the species include: predator control, the protection of nesting sites with fences and moving of nests away from the high tide mark (3). Efforts have been encouragingly successful and the population has increased significantly in the past 10 years (2).
Description
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The Chatham Island oystercatcher is a small, black and white wader (3). The head, back and upperbreast are black whilst the underparts are white and there is a smudgy border on the chest where these two colour bands meet (2). The long, thick bill is red whilst the legs are pink and the eye ring orange (2). Juveniles have heavily speckled underparts and the tail has a conspicuous white band (4).
Habitat
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Chatham Island oystercatchers inhabit rocky or sandy coastlines (3).
Range
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Endemic to the Chatham Islands in New Zealand, breeding pairs are found on South East Island, Pitt Island, Mangere Island and Chatham Island (3).
Status
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Classified as Endangered (EN) on the IUCN Red List 2007 (1).
Threats
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Chatham Island oystercatchers are vulnerable to different threats due to the small size of their population (2). Population estimates in 1987 found numbers to be worryingly low; at just over 100 individuals (3). On Pitt and Chatham Islands introduced predators pose the major threat to the survival of this species. Sheep and cattle also cause problems by trampling on eggs and chicks (3). On Chatham Island, introduced marram grass has spread onto the open areas where these oystercatchers prefer to nest, forcing birds to nest too near to the waters edge where eggs are vulnerable to high tides (2).
Chatham oystercatcher
provided by wikipedia EN
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 yellow 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
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.[2] 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".[4] 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 flightless weka (Gallirallus australis) is also a nest predator.[1]
References
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Chatham oystercatcher: Brief Summary
provided by wikipedia EN
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.
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