Aigle nain

Identification

The little eagle is a medium-sized bird of prey, measuring 45–55 cm (17–21.5 inches) in length and weighing 815 g (1.8 lb), roughly the size of a peregrine falcon.It has fully feathered legs and a square-cut, barred tail. Wingspan is about 120 cm with males having longer wings in proportion to their bodies, but being nearly half the weight of females. It is a powerful bird and during flight has strong wing beats, glides on flat wings and soars on slightly raised or flat wings.<p>The little eagle occurs in light and dark colour forms and generally these colours change with age. The most common is the light form which is dark brown occurring on the back and wings with black streaks on the head and neck, and a sandy to pale under body. The dark form of this eagle is similar except the head and under body is usually darker brown or rich rufous. The sexes are similar with females being larger and typically darker. Juveniles are similar to adults but tend to be more strongly rufous in colour with less contrast in patterns.

Taxonomie

John Gould described the little eagle in 1841. The distinctive pygmy eagle has long been considered a subspecies, but a 2009 genetic study shows it to be distinctive genetically and warrants species status. It is a near relative of both the Palearctic booted eagle and the massive but now extinct Haast's eagle of New Zealand.

Nom scientifique

Hieraaetus morphnoides

Autorité

(Gould, 1841)

Ordre

Accipitriformes

Famille

Accipitridés

Genre

Hieraaetus

Répartition et habitat

Although the little eagle has a large range and can be found in most parts of Australia, except heavily forested parts of the Great Dividing Range. It tends to inhabit open woodland, grassland and arid regions, shunning dense forest. Like so many Australian natives, it faces a deteriorating population due to a loss of habitat and competition from other species. One of the biggest factors to the decline of the little eagle is the decline of rabbits due to the release of the calicivirus, the eagle relied heavily on the rabbit population due to the extinction and massive decline of native terrestrial mammals of rabbit size or smaller such as large rodents, bandicoots, bettongs, juvenile banded hare-wallaby and other wallabies.<p>In the first national bird atlas in 1977–81, the little eagle was reported in 65% of one degree grid cells across Australia, with mostly high reporting rates (more than 40% of surveys per grid) across New South Wales and Victoria. Breeding was recorded in 11% of cells, with the highest rates in New South Wales (NSW) and Victoria. During the second national bird atlas in 1998–2002, the little eagle was recorded in 59% of grid cells, at mostly low reporting rates (recorded in less than 20% of surveys per grid). Breeding was recorded in 5% of grid cells. Overall, there has been a national decline in reporting rate of 14%. In NSW over the last 20 years (two little eagle generations) the decline in reporting rate has been 39%, and over the past 30 years has been 50%, with an accelerating trend since the 1990s. The decline in reporting rate over the past 20 years for the South Eastern Highlands bioregion has been greater than 20%. This bioregion includes the ACT.<p>The little eagle was once common in the ACT, but has undergone significant decline (greater than 70%) over the last 20 years. In the late 1980s there was an estimated 13 breeding pairs in the ACT, occurring mainly in the northern half of the ACT with the highest concentrations found in the Murrumbidgee and the Molonglo river corridors. By 2005 the only breeding record in the ACT was of an unsuccessful nest near Uriarra Crossing. A more intensive ACT survey in 2007 found three breeding pairs, which fledged a total of four young. In 2008 four breeding pairs were recorded and four young were fledged. In 2009, three breeding pairs were recorded with three young being fledged.<p>Typical habitat for the little eagle includes woodland or open forest. Higher abundance of the species is associated with hillsides where there is a mixture of wooded and open areas such as riparian woodlands, forest margins and wooded farmland. Little eagles usually avoid large areas of dense forest, preferring to hunt in open woodland, where the birds use trees for lookouts. In the ACT, little eagles inhabit frequent open woodland and riparian areas.

Migration

Resident species

Conservation

The little eagle was declared as 'Vulnerable' in the Australian Capital Territory under Section 38 of the Nature Conservation Act 1980. It was also listed as 'Vulnerable' in New South Wales (NSW) in Part 1 of Schedule 2 of the NSW Threatened Species Conservation Act 1995 and Gazetted[clarification needed] on 12 February 2012.<p>The little eagle is listed on the IUCN Red List as of least concern. Reasons for it being classified as 'least concern' are that the bird of prey has a huge range, spanning up to 20,000km2 and the population size is only decreasing at a rate of 10% per ten years or 3 generations, instead of the required 30%. The Red List amended the status of the little eagle from "Not Recognized" in 2006 to "Least Concern". Also, the NSW Scientific Committee has made the determination to list the little eagle as a Vulnerable species under the Vulnerable species listing. The reasons for this listing is the reduction of habitat quality or diversity and genetic diversity.<p>The main threats to the species are the destruction and degradation of its foraging and breeding habitat causing it to come into competition with the larger and more dominant wedge-tailed eagle. The wedge-tailed eagle is not necessarily a predator of the little eagle but the two species share common habitat and prey and the large size and dominant nature of the wedge-tailed eagle could mean that the little eagle would be forced out of hunting and breeding grounds or even killed and eaten.

Tendance de la population

stable