Chatham Island oystercatcher  (Haematopus chathamensis)

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).

Endemic to the Chatham Islands in New Zealand, breeding pairs are found on South East Island, Pitt Island, Mangere Island and Chatham Island (3).

Chatham Island oystercatchers inhabit rocky or sandy coastlines (3).

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).

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).

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).

For further information on the Chatham Island oystercatcher see:

• BirdLife International (2000) Threatened Birds of the World. Lynx Edicions and BirdLife International, Barcelona and Cambridge.

Authenticated by BirdLife International Secretariat.
http://www.birdlife.org