New Zealand dabchick  (Poliocephalus rufopectus)

Classified as Vulnerable (VU) on the IUCN Red List 2006 (1).

The New Zealand dabchick is a small grebe which, like all other grebes, is a highly specialized waterbird. It has mostly dark brown plumage with a line of distinctive fine, silvery feathers on its head. The breast and foreneck has a chestnut tinge, and the underparts are dusky to silvery white. The eyes are pale yellow, and it has a black bill. Non-breeding adults are slightly paler, and males are larger than females and have a longer bill (2) (3) (4). Juveniles have irregular white, pale brown and black stripes on their head and neck, creating a mottled appearance (2). Whilst grebes are inept on land, they are fantastic swimmers and divers. The slim, long neck and small head are perfect for diving when searching for food, as are the lobed, flexible toes, used to propelling and steering underwater (5). The New Zealand dabchick is generally a silent bird, except for an occasional wee-ee-ee call, which gave rise to its Maori name Weweia (6).

Occurs only in New Zealand, formerly existing on both islands, but is now found only on the North Island. The largest populations are concentrated around the regions of Rotorua and Taupo (4)

The New Zealand dabchick can be found in small freshwater lakes and pools, or in the sheltered parts of larger lakes. It prefers shallow water with dense vegetation, and can also occur in artificial wetlands such as sewage ponds and farm water supplies. Dabchicks that are not breeding can be found on more open waters (2) (4).

Like many other grebes, the New Zealand dabchick performs elaborate courtship rituals, involving preening, diving under their partner and head-shaking; when they jerk their head back and forth, as if pecking like a hen (7). Breeding occurs all year round, with egg-laying peaking between August and February. Nests are formed from a loose pile of aquatic plants, which are anchored to emergent vegetation, hidden under boat shelters or in small caves partially under water (2) (4). Two to three eggs are laid at a time and both parents take it in turn to incubate them for 22 – 23 days (2). The emerging chicks are independent after about 70 days (8).

As a waterbird, the New Zealand dabchick feeds primarily on aquatic invertebrates, such as freshwater crayfish, molluscs and leeches. They obtain this food mainly by diving, at which they are highly competent, and are able to stay underwater for over 30 seconds. Only the largest food items are brought up to the surface, while most are swallowed underwater. They can also be seen pecking food from the water’s surface, or grabbing midges and flying insects from the air (2).

At present, the New Zealand dabchick population is thought to be stable, as their preferred lake habitat is not declining and they have proven to be able to co-exist successfully with humans (9). However, the extinction of this species on the South Island in the 1960s shows that the dabchick is vulnerable to some threats. The reasons for the species decline and extinction on the South Island are not clear, but possible causes, and therefore factors that could threaten the North Island population, include changes in water quality, destruction of nesting habitat, increased human activity around nesting areas, and predation by introduced rats and mustelids (3). The drainage of marshes in the past would have affected the dabchick, but since the 1940s, further habitat would have become available through the creation of sewage ponds and farm water supplies (10). Nests on lakes are also vulnerable to disturbance from boat wakes, and jet and water-skiers that operate too close to lake margins (9).

In 1997 the IUCN Grebe Specialist Group created a Global Conservation Strategy to ensure the successful recovery of grebe populations and the management of wetlands (10). Particular conservation actions recommended for this species include implementing a regular monitoring programme to detect any population changes, and preparing a species recovery plan should numbers begin to decline again (10). Additionally, existing laws limiting boat and ski speeds on lakes should continue to be enforced and steps should be taken to maintain suitable lake habitats, preventing pollution and the establishment of any further introduced species (9).

View information on this species at the UNEP World Conservation Monitoring Centre.

For further information on this species see:

• Birdlife International:
  http://www.birdlife.org/datazone/species/index.html?action=SpcHTMDetails.asp&sid=3636&m=0
• Fjeldså, J. (2004) The grebes: Podicipedidae. Oxford University Press, Oxford.