Urraca Australiana

Identificación

The adult magpie ranges from 37 to 43 cm (14.5 to 17 in) in length with a 65–85 cm (25.5–33.5 in) wingspan, and weighing 220–350 g (7.8–12.3 oz). Its robust wedge-shaped bill is bluish-white bordered with black, with a small hook at the tip. The black legs are long and strong. The plumage is pure glossy black and white; both sexes of all subspecies have black heads, wings and underparts with white shoulders. The tail has a black terminal band. The nape is white in the male and light greyish-white in the female. Mature magpies have dull red eyes, in contrast to the yellow eyes of currawongs and white eyes of Australian ravens and crows. The main difference between the subspecies lies in the "saddle" markings on the back below the nape. Black-backed subspecies have a black saddle and white nape. White-backed subspecies have a wholly white nape and saddle. The male Western Australian subspecies dorsalis is also white-backed, but the equivalent area in the female is scalloped black.<p>Juveniles have lighter greys and browns amidst the starker blacks and whites of their plumage; two- or three-year-old birds of both sexes closely resemble and are difficult to distinguish from adult females. Immature birds have dark brownish eyes until around two years of age. Australian magpies generally live to around 25 years of age, though ages of up to 30 years have been recorded. The reported age of first breeding has varied according to area, but the average is between three and five years.<p>Well-known and easily recognisable, the Australian magpie is unlikely to be confused with any other species. The pied butcherbird has a similar build and plumage, but has white underparts unlike the former species' black underparts. The magpie-lark is a much smaller and more delicate bird with complex and very different banded black and white plumage. Currawong species have predominantly dark plumage and heavier bills.<p>One of Australia's most highly regarded songbirds, the Australian magpie has a wide variety of calls, many of which are complex. Pitch may vary as much as four octaves, and the bird can mimic over 35 species of native and introduced bird species, as well as dogs and horses. Magpies have even been noted to mimic human speech when living in close proximity to humans. Its complex, musical, warbling call is one of the most familiar Australian bird sounds. In Denis Glover's poem "The Magpies", the mature magpie's call is described as quardle oodle ardle wardle doodle, one of the most famous lines in New Zealand poetry, and as waddle giggle gargle paddle poodle, in the children's book Waddle Giggle Gargle by Pamela Allen. The bird has been known to mimic environmental sounds as well, including the noises made by emergency vehicles during the New South Wales wildfire state of emergency for Australian bushfire.<p>When alone, a magpie may make a quiet musical warbling; these complex melodious warbles or subsongs are pitched at 2–4 KHz and do not carry for long distances. These songs have been recorded as being up to 70 minutes long, and are more frequent after the end of the breeding season. Pairs of magpies often take up a loud musical calling known as carolling to advertise or defend their territory; one bird initiates the call with the second (and sometimes more) joining in. Often preceded by warbling, carolling is pitched between 6 and 8 kHz and has 4–5 elements with slurring indistinct noise in between. Birds adopt a specific posture by tilting their heads back, expanding their chests, and moving their wings backwards. A group of magpies sing a short repetitive version of carolling just before dawn (dawn song), and at twilight after sundown (dusk song), in winter and spring.<p>Fledgling and juvenile magpies emit a repeated short and loud (80 dB), high-pitched (8 kHz) begging call. Magpies may indulge in beak-clapping to warn other species of birds. They employ several high pitched (8–10 kHz) alarm or rallying calls when intruders or threats are spotted. Distinct calls have been recorded for the approach of eagles and monitor lizards.

Taxonomía

Nombre científico

Gymnorhina tibicen

Autoridad

(Latham, 1801)

Orden

Passeriformes

Familia

Artamidae

Género

Gymnorhina

Distribución y hábitat

The Australian magpie is found in the Trans-Fly region of southern New Guinea, between the Oriomo River and Muli Strait, and across most of Australia, bar the tip of Cape York, the Gibson and Great Sandy Deserts, and the southwest of Tasmania.<p>The Australian magpie prefers open areas such as grassland, fields and residential areas such as parks, gardens, golf courses, and streets, with scattered trees or forest nearby. Birds nest and shelter in trees but forage mainly on the ground in these open areas. It has also been recorded in mature pine plantations; birds only occupy rainforest and wet sclerophyll forest in the vicinity of cleared areas. In general, evidence suggests the range and population of the Australian magpie has increased with land-clearing, although local declines in Queensland due to a 1902 drought, and in Tasmania in the 1930s have been noted; the cause for the latter is unclear but rabbit baiting, pine tree removal, and spread of the masked lapwing (Vanellus miles) have been implicated.<p>Birds taken mainly from Tasmania and Victoria were introduced into New Zealand by local Acclimatisation Societies of Otago and Canterbury in the 1860s, with the Wellington Acclimatisation Society releasing 260 birds in 1874. White-backed forms are spread on both the North and eastern South Island, while black-backed forms are found in the Hawke's Bay region. Magpies were introduced into New Zealand to control agricultural pests, and were therefore a protected species until 1951. They are thought to affect native New Zealand bird populations such as the tūī and kererū, sometimes raiding nests for eggs and nestlings, although studies by Waikato University have cast doubt on this, and much blame on the magpie as a predator in the past has been anecdotal only. Introductions also occurred in the Solomon Islands and Sri Lanka, although the species has failed to become established. It has become established in western Taveuni in Fiji, however.

Migración

Resident species

Comportamiento

The Australian magpie is almost exclusively diurnal, although it may call into the night, like some other members of the Artamidae. Natural predators of magpies include various species of monitor lizard and the barking owl. Birds are often killed on roads or electrocuted by powerlines, or poisoned after killing and eating house sparrows, mice, rats or rabbits that have eaten poison bait. The Australian raven may take nestlings left unattended.<p>On the ground, the Australian magpie moves around by walking, and is the only member of the Artamidae to do so; woodswallows, butcherbirds and currawongs all tend to hop with legs parallel. The magpie has a short femur (thigh bone), and long lower leg below the knee, suited to walking rather than running, although birds can run in short bursts when hunting prey.<p>The magpie is generally sedentary and territorial throughout its range, living in groups occupying a territory, or in flocks or fringe groups. A group may occupy and defend the same territory for many years. Much energy is spent defending a territory from intruders, particularly other magpies, and different behaviours are seen with different opponents. The sight of a raptor results in a rallying call by sentinel birds and subsequent coordinated mobbing of the intruder. Magpies place themselves either side of the bird of prey so that it will be attacked from behind should it strike a defender, and harass and drive the raptor to some distance beyond the territory. A group will use carolling as a signal to advertise ownership and warn off other magpies. In the negotiating display, the one or two dominant magpies parade along the border of the defended territory while the rest of the group stand back a little and look on. The leaders may fluff their feathers or caroll repeatedly. In a group strength display, employed if both the opposing and defending groups are of roughly equal numbers, all magpies will fly and form a row at the border of the territory. The defending group may also resort to an aerial display where the dominant magpies, or sometimes the whole group, swoop and dive while calling to warn an intruding magpie's group.<p>A wide variety of displays are seen, with aggressive behaviours outnumbering pro-social ones. Crouching low and uttering quiet begging calls are common signs of submission. The manus flutter is a submissive display where a magpie will flutter the primary feathers in its wings. A magpie, particularly a juvenile, may also fall, roll over on its back and expose its underparts. Birds may fluff up their flank feathers as an aggressive display or preceding an attack. Young birds display various forms of play behaviour, either by themselves or in groups, with older birds often initiating the proceedings with juveniles. These may involve picking up, manipulating or tugging at various objects such as sticks, rocks or bits of wire, and handing them to other birds. A bird may pick up a feather or leaf and fly off with it, with other birds pursuing and attempting to bring down the leader by latching onto its tail feathers. Birds may jump on each other and even engage in mock fighting. Play may even take place with other species such as blue-faced honeyeaters and Australasian pipits.<p>A 2022 study showed cooperative behaviour, along with a moderate level of problem-solving, when magpies (G. tibicen) assisted one another to remove tracking devices placed on their bodies in a specially-designed harness by researchers for conservation purposes. This was the first recorded example of birds acting in this way to remove tracking devices, a form of rescue behaviour.<p>Magpies have a long breeding season which varies in different parts of the country; in northern parts of Australia they will breed between June and September, but not commence until August or September in cooler regions, and may continue until January in some alpine areas. The nest is a bowl-shaped structure made of sticks and lined with softer material such as grass and bark. Near human habitation, synthetic material may be incorporated. Nests are built exclusively by females and generally placed high up in a tree fork, often in an exposed position. The trees used are most commonly eucalypts, although a variety of other native trees as well as introduced pine, Crataegus, and elm have been recorded. Other bird species, such as the yellow-rumped thornbill (Acanthiza chrysorrhoa), willie wagtail (Rhipidura leucophrys), southern whiteface (Aphelocephala leucopsis), and (less commonly) noisy miner (Manorina melanocephala), often nest in the same tree as the magpie. The first two species may even locate their nest directly beneath a magpie nest, while the diminutive striated pardalote (Pardalotus striatus) has been known to make a burrow for breeding into the base of the magpie nest itself. These incursions are all tolerated by the magpies. The channel-billed cuckoo (Scythrops novaehollandiae) is a notable brood parasite in eastern Australia; magpies will raise cuckoo young, which eventually outcompete the magpie nestlings.<p>The Australian magpie produces a clutch of two to five light blue or greenish eggs, which are oval in shape and about 30 by 40 mm (1.2 by 1.6 in). The chicks hatch synchronously around 20 days after incubation begins; like all passerines, the chicks are altricial—they are born pink, naked, and blind with large feet, a short broad beak and a bright red throat. Their eyes are fully open at around 10 days. Chicks develop fine downy feathers on their head, back and wings in the first week, and pinfeathers in the second week. The black and white colouration is noticeable from an early stage. Nestlings are usually fed exclusively by the female, though the male magpie will feed his partner. Individual males do feed nestlings and fledglings, to varying degrees, from sporadic to equal frequency to the female. The Australian magpie is known to engage in cooperative breeding, and helper birds will assist in feeding and raising young. This does vary from region to region, and with the size of the group—the behaviour is rare or non-existent in pairs or small groups.<p>Juvenile magpies begin foraging on their own three weeks after leaving the nest, and mostly feeding themselves by six months old. Some birds continue begging for food until eight or nine months of age, but are usually ignored. Birds reach adult size by their first year. The age at which young birds disperse varies across the country, and depends on the aggressiveness of the dominant adult of the corresponding sex; males are usually evicted at a younger age. Many leave at around a year old, but the age of departure may range from eight months to four years.<p>The Australian magpie is omnivorous, eating various items located at or near ground level including invertebrates such as earthworms, millipedes, snails, spiders and scorpions as well as a wide variety of insects—cockroaches, ants, earwigs, beetles, cicadas, moths and caterpillars and other larvae. Insects, including large adult grasshoppers, may be seized mid-flight. Skinks, frogs, mice and other small animals as well as grain, tubers, figs and walnuts have also been noted as components of their diet. <p>It has even learnt to safely eat the poisonous cane toad by flipping it over and consuming the underparts. Predominantly a ground feeder, the Australian magpie paces open areas methodically searching for insects and their larvae. One study showed birds were able to find scarab beetle larvae by sound or vibration. Birds use their bills to probe into the earth or otherwise overturn debris in search of food. Smaller prey are swallowed whole, although magpies rub off the stingers of bees, stinging ants and wasps and irritating hairs of caterpillars before swallowing.

Conservación

Tendencia poblacional

rising