Variable oystercatcher

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Variable oystercatcher

The variable oystercatcher (Haematopus unicolor) is a shorebird found only in New Zealand. Its Māori name is tōrea-pango, and it is sometimes called the red-billed oystercatcher.

Description
This bird shows many color forms. It can be black, mottled, or pied (black and white). Northern birds have more white, while those on Stewart Island are entirely black. It has pink legs, an orange eye ring, and a long orange-red bill that deepens to red during the breeding season. Adults are about the size of a large crow, with a body about 42–47 cm long and a weight around 0.7 kg. Females are slightly larger than males.

Distribution and habitat
The variable oystercatcher is endemic to New Zealand. It lives along most coastlines of the North and South Islands and some offshore islands, but not on all western offshore islands. It usually stays within 30 km of the coast and breeds on sandy beaches or dunes, away from muddy harbors.

Behaviour
In flight the birds emit a high-pitched “kleep kleep.” They are active day and night, feeding mainly when the tide is moving. If food is hidden or it is dark, they can locate it by probing with their bill. Their diet includes molluscs (especially shellfish), crustaceans, worms, and other small invertebrates, and sometimes small fish. After heavy rain they may go inland to hunt earthworms.

Breeding
Variable oystercatchers are sedentary and breed on the coastal dunes where they live. The male performs bowing and head-dipping displays to attract a mate and defend its territory. Pairs are usually monogamous for the breeding season and often for several years. Nests are shallow scrapes in sand or shingle, sometimes lined with seaweed. Clutch size is typically 2–3 eggs, but up to 5 can occur. Eggs hatch after about 25–32 days. Both parents guard the nest and care for the chicks, which fledge around February–March and can fly at about 6 weeks. Juveniles join loose flocks in early fall (around August) and stay with other youngsters until they reach breeding age around 3 years old.

Conservation
The species is estimated to have about 4,000–5,000 individuals and is currently listed as Least Concern. The population has been increasing over recent generations. No specific conservation program exists, but coastal protections help. In the Wellington region, it is considered Regionally Vulnerable. Historically, disturbance and habitat loss, along with predators such as cats, dogs, and gulls, have affected the birds. Occasional parasites and rare diseases have been recorded, but they are not major causes of mortality.