Post by Eaglehawk on Aug 29, 2019 10:55:55 GMT
Weka - Gallirallus australis
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Gruiformes
Family: Rallidae
Genus: Gallirallus
Species: G. australis
The weka (also known as Maori hen or woodhen) (Gallirallus australis) is a flightless bird species of the rail family. It is endemic to New Zealand, where four subspecies are recognized. Weka are sturdy brown birds, about the size of a chicken. As omnivores, they feed mainly on invertebrates and fruit. Weka usually lay eggs between August and January; both sexes help to incubate.
Description
Weka are large rails. They are predominantly rich brown mottled with black and grey; the brown shade varies from pale to dark depending on subspecies. The male is the larger sex at 50–60 cm (20–24 in) in length and 532–1,605 g (1.173–3.538 lb) in weight. Females measure 46–50 cm (18–20 in) in length and weigh 350–1,035 g (0.772–2.282 lb). The reduced wingspan ranges from 50 to 60 cm (20 to 24 in). The relatively large, reddish-brown beak is about 5 cm (2.0 in) long, stout and tapered, and used as a weapon. The pointed tail is near-constantly being flicked, a sign of unease characteristic of the rail family. Weka have sturdy legs and reduced wings.
Taxonomy and distribution
The common name, "weka", is a Māori word. The species was named Rallus australis by Anders Erikson Sparrman in 1789. Sparrman published the information in Museum Carlsonianum, four fascicules based on specimens collected while voyaging with Captain James Cook between 1772 and 1775. Australis is Latin for "southern". Johann Georg Wagler's suggestion of the Ocydromus genus in 1830 to describe each weka as a species was generally adopted. However, weka were later decided as a single species in the Gallirallus genus with four subspecies.
- The Buff Weka (Gallirallus australis hectori) formerly inhabited the eastern districts of the South Island but is now confined to Chatham Island and Pitt Island to which it was introduced in the early 1900s, and where they are widely hunted and eaten, being considered 'introduced'. Reintroduction into Canterbury has been unsuccessful so far but introductions to Mao Waho Island (in Lake Wanaka in 2004) and from there to Pigeon and Pig Island (in Lake Wakatipu in 2005/2006) have been much more successful. It has a lighter overall colouring than the other subspecies.
/li]
[li][The North Island Weka (Gallirallus australis greyi) is represented by original populations in Northland and Poverty Bay, and by liberations elsewhere from that stock. This subspecies differs in its greyer underparts, and brown rather than reddish coloured legs. - [The Western Weka (Gallirallus australis australis) is found mainly in the northern and western regions of the South Island from Nelson to Fiordland. Distinguished by dark red-brown and black streaking on the breast, the western weka has two distinct colour phases, that of the southernmost range showing a greater degree of black.
- [The Stewart Island Weka (Gallirallus australis scotti) is smaller than the other subspecies and, like the western weka, has two colour phases; a chestnut form - similar to the chestnut-phase western weka - and a black phase which is not as dark as the black western weka. The population is confined to Stewart Island/Rakiura and outliers, and to Kapiti Island to which it was introduced.
Behaviour
Habitat and diet
Weka occupy areas such as forests, sub-alpine grassland, sand dunes, rocky shores and modified semi-urban environments. They are omnivorous, with a diet comprising 30% animal foods and 70% plant foods. Animal foods include earthworms, larvae, beetles, weta, ants, grass grubs, slugs, snails, insect eggs, slaters, frogs, spiders, rats, mice, and small birds. Plant foods include leaves, grass, berries and seeds. Weka are important in the bush as seed dispersers, distributing seeds too large for smaller berry-eating birds. Where the weka is relatively common, their furtive curiosity leads them to search around houses and camps for food scraps, or anything unfamiliar and transportable.
Breeding and nesting
The breeding season varies, but when food is plentiful, weka can raise up to four broods throughout the whole year. Nests are made on the ground under the cover of thick vegetation, and built by making grass (or similar material) into a bowl to hold about four eggs. On average, female weka lay three creamy or pinkish eggs blotched with brown and mauve. Both sexes incubate. The chicks hatch after a month, and are fed by both parents until fully grown between six and ten weeks.
Conservation status
Weka are classed as a vulnerable species. The Department of Conservation's weka recovery plan, approved in 1999, aims to improve the conservation status of threatened weka, clarify the status of data deficient weka, maintain the non-threatened status of other weka, and eventually restore all weka to their traditional ranges as a significant component of the ecosystems.
Weka are problematic in conservation; some subspecies are threatened, but have been a problem to other threatened wildlife on offshore islands, especially when introduced to an island that they would not naturally inhabit. Weka are unable to withstand the current pressures faced in both the North Island and South Island. However, they can be very productive in good conditions and high food availability. Year-round breeding has been recorded at several sites with up to 14 young produced in a year. Weka populations can persist in highly modified habitats, but they have disappeared from huge areas of their former range, suggesting that they can adapt to a wide range of conditions but are particularly vulnerable to threats.
Threats
The Department of Conservation identifies eight main threats to weka. Predation by ferrets, cats, and dogs are a threat to adult weka; stoats and ferrets are a threat to chicks; stoats and rats are a threat to eggs. It faces competition with introduced species for fruits and invertebrates, and suffers from the impact browsers have on forest composition and regeneration. Habitat depletion is caused by the modification and degradation of forests and wetlands. Diseases and parasites have been associated with population declines, although little is known. Drought has been implicated in the disappearance of weka from some areas. In some regions, motor vehicles cause a significant amount of roadkill death. Pest control operations sometimes kill weka, as they have ground foraging habits vulnerable to poison baits, and traps are laid in a way that weka can reach. Genetic diversity can be lost during the transmission of genes through generations, affecting isolated populations.
Human interaction and folklore
Weka are significant to some Māori iwi who admire their curiosity and feisty, bold personality, traits which have led to them being relatively easy to catch. Weka were used by the Māori as a source of food, perfume, oil to treat inflammations, feathers in clothing and lures to catch dogs. Early European explorers and settlers frequently encountered and utilised weka; they were called "bush hens".
Tales of weka stealing shiny items and bags of sugar are part of New Zealand folklore.
The rise of the weka: Suburban raiders causing havoc
"A cheeky little invader is taking over Nelson, raiding cat dishes and digging up vege patches.
The inquisitive weka might be flightless but its population in the region has taken off, leaving bird experts mystified.
Ornithologist Peter Gaze said the weka's resurgence in the region was somewhat of a phenomenon.
The weka that was living behind the Nelson post office in Hardy Street.
"In everyone's backyards, the cat food is getting eaten, the goldfish are getting eaten, the vege gardens are getting scratched up by this flightless native bird," Gaze said.
Gaze said it was one of the few native birds that was managing to make a comeback.
One of Nancy Holden's chickens gives the resident weka a run for its money near Atawhai, Nelson.[
The reasons for the bird's population growth in the top of the south were unclear but trapping programmes across the region were likely to have helped.
Amongst the stories of home invasions were tales of weka terrorising cats, attacking pet chickens and in some cases even stealing their eggs.
"It creates a little bit of a dilemma for people, people who love to have native birds around but once they start digging up the radishes and giving the domestic cat a hard time their sympathies fade in a hurry."
[A baby weka runs across the lawn at Mahoe Hills, owned by Marion and Henk van Oeveren in Garden Valley Rd.
Katherine Chamberlain has been collecting data on weka in Nelson for the last 18 months, prompted by the headline-making exploits of a cheeky individual which moved into the garden behind the central city post office in 2013.
She said the data indicated the number population had begun to increase in the last five or six years.
Rumour had it that weka from Reefton were even catching a lift up the West Coast in rubbish trucks and getting out at the York Valley landfill in Nelson.
"Now we are starting to see them on roundabouts, they have been right down on Wakefield Quay, up by the beach. I have had people report seeing them crossing busy roads so they are definitely spreading out," she said.
Chicks had been seen between May and July, despite the bird's typical breeding period being between August and February. This showed the habitat was good and there was an abundance of food.
She said it was important to raise awareness and understanding of weka to avoid potential conflicts so people could enjoy having them around.
"It is an exciting challenge to have, having native animals in your garden and learning to live with them.""
www.stuff.co.nz/environment/81579216/feathered-little-raiders-causing-havoc
Shameless thief or good forest citizen? Weka bring hidden benefits to New Zealand forests
by University of Canterbury
University of Canterbury doctoral candidate Jo Carpenter on Ulva Island, off Rakiura/Stewart Island, holding a weka. Credit: Theo Thompson
Weka are often portrayed as little more than sandwich-stealing scallywags. The large, brown flightless bird's tendency to be curious and gobble any food available (whether it be an unwatched biscuit, penguin egg or endangered gecko) also makes them troublesome for conservationists. However, a new study by University of Canterbury and Department of Conservation researchers has found that these charismatic birds also perform important services for Aotearoa New Zealand forests.
Although birds like the kererū (wood pigeon) tend to get credit for dispersing seeds, it turns out weka are important seed dispersers for some New Zealand plants. They eat the fruits of many plant species, and have a large beak that allows them to also eat fruits that smaller birds can't manage. A new study, published today in Royal Society Open Science, found that weka even disperse some seeds as far as kererū do.
"You might think that because weka are flightless they wouldn't be very good at moving seeds large distances," says lead author Jo Carpenter, a University of Canterbury (UC) Ecology Ph.D. student now based at Manaaki Whenua | Landcare Research. "But it turned out they were dispersing a small proportion of seeds over two kilometres—that's a long way for a seed."
The researchers investigated how far weka moved seeds by attaching GPS transmitters to over 40 birds, then figuring out how long it took seeds to pass through weka. By understanding how long it takes a seed to typically pass through a weka, they could model how far seeds eaten by weka would be travelling. Because some seeds stay inside the birds as long as six weeks, the weka can deposit them far from where they were eaten.
The researchers also made a worrying discovery. Weka near public campsites didn't move seeds as far as those in remote areas. In fact, weka at campsites dispersed seeds 35-40% shorter distances than weka in nearby forests.
"This is an example of what is known as 'cryptic function loss,'" says co-author UC Ecology Professor Dave Kelly, Biological Sciences, who supervised Carpenter's doctoral research thesis titled: Legacy of Loss: Seed Dispersal by Kererū and Flightless Birds in New Zealand.
"It's what happens when an animal is still present in an ecosystem, but due to human impacts it's not providing the ecosystem services that keep everything working properly. We think that weka that spend more time at campsites get more food from people, and therefore don't have to forage as far. That means they disperse seeds shorter distances," Professor Kelly says.
These reduced seed-dispersal distances could affect long-term forest replacement, especially in human-modified landscapes where dispersal maintains genetic diversity across surviving forest patches. This might be a particular problem for large-seeded native trees, like hinau, for which weka are one of the most important seed dispersers.
"This is one of the first studies showing that interaction with people could have a significant effect on the quality of seed dispersal performed by an animal. That's concerning because even our wild places are becoming increasingly crowded with people," says Carpenter.
"So next time you see a weka, think twice before you offer it your lunch!"
More information: Legacy of Loss: Seed Dispersal by Kererū and Flightless Birds in New Zealand: ir.canterbury.ac.nz/handle/10092/16731
phys.org/news/2019-08-shameless-thief-good-forest-citizen.html