Weka (Gallirallus australis)
|Also known as:||woodhen|
|Size||Male length: 50 – 60 cm (2)|
Female length: 46 – 50 cm (2)
Wingspan: 50 – 60 cm (2)
Male weight: 532 – 1605 g (2)
Female weight: 350 – 1035 g (2)
Classified as Vulnerable (VU) on the IUCN Red List 2006 (1).
The weka, a famously inquisitive and feisty bird, is a member of the rail family Rallidae; a group of ground dwelling birds, some of which, including the weka, have lost the ability to fly over evolutionary time. In appearance it is unmistakable; its hefty body is covered with a rich brown plumage streaked with black, and it possesses a remarkably long tail for a flightless bird (2) (3). The bill is moderately long, and it has powerful legs and un-webbed feet (4). There are four subspecies of the weka, each with slight differences in their appearance. Both Gallirallus australis australis and Gallirallus australis scotti have three morphs, or forms, each with a brown plumage tinged with chestnut, grey or black, but G. a scotti is distinguished by being the smallest of them all. Gallirallus australis greyi is a very dark brown with a dark grey belly, whilst Gallirallus australis hectori is more yellowish-brown, and the palest of the four subspecies (2).The calls of the weka are most frequently heard at dawn, dusk and early evening. A loud shrill whistling coo-eet is repeated, often sung in a duet by a pair of weka (2). During aggressive or territorial encounters the weka makes a booming doon-doon-doon call instead (2). On a quiet night the calls of a weka can be heard for over a mile (3).
The weka is found only in New Zealand. G. a. australis occurs on the North and west South Islands, G. a. scotti is found on Stewart Island, and G. a. greyi occurs on North Island. G. a. hectori was formerly known from eastern and central South Island, but is now only found on Chatham Island where it was introduced (2).
Occurs in a wide range of habitats; from forests and grasslands, to coastal wetlands and cultivated fields, and even urban environments. It prefers areas with some vegetation, to provide the bird with cover, but not so much that it hinders its movement. It can be found from sea level up to altitudes of 1500 m (2).
The weka is an omnivorous bird that will grasp any opportunity for food; they are known to steal eggs from domestic hens, vegetables from allotments, and anything edible from campsites (3) (4). In forests, the weka feeds primarily on fallen fruits and invertebrates, including earthworms, molluscs, insects and crustaceans. They also prey on lizards, frogs, the eggs and young of birds, and even sometimes kill rats, mice, chickens, young ducks and rabbits (2). If the opportunity arises, they will also scavenge from carcasses (2). To find and eat such a great variety of food requires a range of tactics. They rummage through leaf litter, lifting large dead palm leafs, and search thoroughly in seaweed and other beach debris. They probe tree hollows and burrows, and often follow wild pigs to search where they have rooted. Their sturdy bill can spear eggs, and can also be used as a hammer, to kill or break up large objects which are held down by its feet (2).
The breeding season of the weka varies depending on the climate, food availability and size of the population, but can be all year round (2) (5). As monogamous birds, they have only one mate during a breeding season, and sometimes a bond may last throughout the breeding life of a pair (2). Weka are also territorial, and within their territory they nest on dry ground, usually in dense cover, such as in tussocks, burrows, tree hollows, under logs, stumps or rocks, or even hidden in outbuildings (2). The nest is a shallow cup of woven grasses, lilies, twigs and moss, lined with finer grasses, and sometimes feathers, wool, hair or leaves, built by both of the parents or the male only (2). An average of two to four eggs are laid in each clutch and are incubated by the female during the day, and the male at night, for a period of 26 – 28 days. The chicks leave the nest after two to three days, but are cared for by both parents for approximately two months (2) (3). Weka may rear up to four broods a year, and so after two months they are ready to lay another clutch of eggs, and thus begin to drive their current young away (2) (3). Whilst the young may appear somewhat bewildered at their parent’s sudden change of behaviour, it is not long before they leave their parent’s territory to establish their own, and lay their first clutch of eggs (3).
Weka can adapt to a wide range of conditions, persist in highly modified habitats, and be very productive (6). However, despite this, the weka appears to also be susceptible to rapid population declines and local extinctions, the causes of which are complex, and vary between each region (5) (6). The clearance and degradation of many forests and wetlands reduces numbers of weka, as does introduced mammals which prey on the weka; adults are taken by ferrets and domestic dogs, and chicks and eggs are eaten by stoats, cats and rats (5) (6). Introduced species also affect the weka by competing for food sources such as fruit and invertebrates (6). In some areas a significant number of weka are killed by road traffic, and in others, weka die after consuming poisoned bait laid for possum and rabbit control (5) (6). Extended periods of drought also contribute to a decline in weka numbers in some regions (6). Historically, the weka was hunted by some Maori and early European explorers, their curious nature making them relatively easy to catch. They were used for food, perfume, oil and feathers, but today the weka is only legally harvested on the Chatham Islands (7).
The weka is an unusual species in conservation terms, in that whilst in some regions it is threatened, in other areas it can become a problem to other threatened wildlife, especially when they have been introduced to an island outside their natural range (6). Any conservation measures need to take these two opposing problems into account. The New Zealand Department of Conservation Weka Recovery Plan was approved in 1999, which outlines different management options and a work plan, to promote the recovery of the weka (6). The plan includes actions such as determining the exact distribution and status of all subspecies, researching the impacts and management of threats, and establishing further populations to ensure that each subspecies has at least one large mainland population and three island populations (5).
For further information on the conservation of the weka see the New Zealand Department of Conservation, with links to the Recovery Plan:
For more information on this and other bird species please see:
- BirdLife International:
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- Crustaceans: diverse group of arthropods (a phylum of animals with jointed limbs and a hard chitinous exoskeleton) characterised by the possession of two pairs of antennae, one pair of mandibles (parts of the mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, slaters, woodlice and barnacles.
- Invertebrates: animals with no backbone.
- Molluscs: a diverse group of invertebrates, mainly marine, that have one or all of the following; a horny, toothed ribbon in the mouth (the radula), a shell covering the upper surface of the body, and a mantle or mantle cavity with a type of gill. Includes snails, slugs, shellfish, octopuses and squid.
- Monogamous: having only one mate during a breeding season, or throughout the breeding life of a pair.
- Subspecies: a population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.
IUCN Red List (July, 2014)