Adelie Penguin

Identificazione

The Adélie penguin is a mid-sized bird, measuring 70–73 cm (28–29 in) in length and weighing 3.8 to 8.2 kg (8.4 to 18.1 lb). Although the sexes look the same, females have shorter wings and beaks and weigh significantly less. The adult is black on the head, throat and upper parts, with snowy white underparts. It has a conspicuous white eye ring around a black iris. The beak is largely covered with black feathers, leaving only the tip exposed; this is primarily black, though it can show indistinct reddish-brown markings. The upper surface of the wing is black with a white trailing edge, while the underside is white with a narrow black leading edge and a small black tip. The legs and feet, which are mostly unfeathered, are pinkish.<p>Upon hatching, the chick is fully covered in down feathers. This coat of feathers is typically silvery-grey (darker on the head), though some birds are much darker overall. Within 10 days, the chick moults into another set of down feathers, this time all dark smoky-grey. Once they have moulted a third time, 7–9 weeks after hatching, the immature birds are similar to adults in appearance, though they tend to be smaller with a bluer tinge to their upperparts and white (rather than black) chins and throats. They lack the full white eye ring of the adult until they are at least a year old.<p>The adult Adélie penguin is unlikely to be confused with any other species, but the white-throated immature bird can resemble the chinstrap penguin. However, the black on its face extends below its eyes, and it lacks a black line under the throat (the "chinstrap") that the chinstrap penguin has. In addition, the bill of the chinstrap penguin is longer, and lacks the feathering that covers most of the bill of the Adélie penguin.

Tassonomia

The first Adélie penguin specimens were collected by crew members of French explorer Jules Dumont d'Urville on his expedition to Antarctica in the late 1830s and early 1840s. Jacques Bernard Hombron and Honoré Jacquinot, two French surgeons who doubled as naturalists on the journey, described the bird for science in 1841, giving it the scientific name Catarrhactes adeliæ. They used specimens collected from an area of the continent which had been named "terre Adélie", French for Adélie Land, itself named for Dumont d'Urville's wife, Adèle. The bird was later placed in several other genera, including Eudyptes, Pygoscelis and the now-defunct genus Dasyrhamphus, and was also later inadvertently redescribed as Pygoscelis brevirostris.<p>The Adélie penguin is one of three species now assigned to the genus Pygoscelis. DNA evidence suggests the Pygoscelis lineage diverged from that of other penguin species some 38 million years ago, roughly 2 million years after the ancestors of the genus Aptenodytes diverged. Adélie penguins evolved about 19 million years ago, branching from the ancestor of the other two members of the genus (chinstrap and gentoo penguins), both of which evolved some 5 million years later. Although it has no identifiable subspecies, the Adélie penguin has two distinct genetic lineages: one found primarily in the Ross Sea, and the other widespread throughout the Antarctic. <p>The genus name Pygoscelis is a compound word, composed of the Ancient Greek words pugē, meaning "rump", and skelos, meaning "leg". The members of this genus are often called "brush-tailed penguins", a reference to their long, stiff tail feathers. The birds regularly use their tails for support, and the stiff feathers sweep the ground as the penguins walk. The specific name adeliae indicates the location from which the type specimen was collected.

Nome scientifico

Pygoscelis adeliae

Autorità

(Hombron & Jacquinot, 1841)

Ordine

Sfenisciformi

Famiglia

Spheniscidae

Genere

Pygoscelis

Areale e habitat

The Adélie penguin is a truly Antarctic creature – one of only four penguin species to nest on the continent itself. Breeding colonies are scattered along Antarctica's coasts and on a number of sub-Antarctic islands, including those in the South Orkneys, the South Shetlands, the South Sandwich Islands, the Balleny Islands, Scott Island and South Georgia. The penguins are much less common north of the 60th parallel south but have occurred as vagrants in Australia, New Zealand and southern South America. During the breeding season, they need bare, rocky ground on which to build their nests. They will not nest on ice, and preferentially choose areas where wind or the angle of the sun (or both) helps to keep snow drifts from accumulating. At the start of the breeding seasons, colony sites may be up to 100 km (62 mi) from open water, though the distance decreases as summer progresses and the pack ice breaks up.<p>Once they have finished breeding, adult Adélie penguins typically move to ice floes or ice shelves to moult, though some remain onshore. During the winter, the birds remain in the pack ice zone, with most moving north to reach areas where there is visible light for at least part of the day – thus north of roughly 73°S. While some remain near their breeding colonies, others may move hundreds or thousands of kilometres away. As long as there are breaks in the pack ice, they can survive hundreds of kilometres south of open water, and birds are known to forage in winter in areas with up to 80% pack ice cover.

Areale riproduttivo

SO, AN : Antarctic coasts and islands

Areale non riproduttivo

Fino al margine della banchisa

Migrazione

Migratori completi

Comportamento

Comportamento migratorio: Migratori completi.

Conservazione

Tendenza della popolazione: in aumento.

Tendenza della popolazione

in aumento