Aguilucho de Azara

Identificación

The long-winged is mid-sized bird of prey, and like most birds of prey species, the females are larger than the males. Males will weigh from 390 to 464 g (13.8 to 16.4 oz) and females will be slightly heavier, ranging from 400 to 645 g (14.1 to 22.8 oz). Their length can range between 46 and 60 cm (18 and 23.5 in) and their wingspan ranges between 120 and 155 cm (47 and 61 in). As other harrier species, the lon-winged harrier can be identified by its long and narrow tail and its especially long wings. Their wings and their back are mostly grey, with the primary feathers on the wings being much darker than the rest of the wing feathers, which are streaked with variants of white, grey and brown.<p>The long-winged harrier can arbor 2 different morphs, a dark morph and a light morph. In dark morph individuals, the belly is all black with females having more of a brown undertone. The light morph individuals can be identified by their white underparts, which contrasts heavily with their dark morph counterpart. Juvenile long-winged harriers usually have the same colour patterns as females, but they have a more speckled chest. The long-winged harrier morphologically resembles its close relative, the cinereous harrier (Circus cinereus), which can also be found in South America, but their range rarely overlaps.<p>As all other birds of prey species, the long-winged harrier possesses sharp talons used to catch their prey on the ground or in the air, and their legs are bright orange. The species also shares the large hooked beak of other birds of prey, which it uses to tear apart meat once it catches its prey.<p>The long-winged harrier is part of the only diurnal bird of prey group to possess a facial disc. The facial disc is formed by a group of easily recognizable group of feathers that form a disc shape around the bird's face. These feathers can be raised in response to sounds and can improve the bird's hearing when it is hunting by triangulating sounds in its ear holes.<p>Little is known of the long-winged harrier's vocalization, as is not a very vocal bird. It will call mostly when in flight and some variation of the bird's call include a fast succession of "klee-klee-klee", and a more quiet "thrill" with a quickly descending pitch.

Taxonomía

The long-winged harrier was formally described in 1788 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae. He placed it with the falcons, eagles and their relatives in the genus Falco and coined the binomial name Falco buffoni. Gmelin based his description on the "Cayenne ringtail" that had been described in 1781 by the English ornithologist John Latham in his multi-volume work A General Synopsis of Birds. Latham had examined a specimen from Cayenne that formed part of a private collection in London. The specimen had been given the title "Duc de Buffon". The long-winged harrier is now one of 16 harriers placed in the genus Circus that was introduced in 1799 by the French naturalist Bernard Germain de Lacépède. The genus name Circus is derived from the Ancient Greek kirkos, referring to a bird of prey named for its circling flight (kirkos, "circle"), probably the hen harrier. The specific epithet buffoni is from the name of the French naturalist, the Comte de Buffon. The long-winged harrier does not have any recognised subspecies.

Nombre científico

Circus buffoni

Autoridad

(Gmelin, JF, 1788)

Orden

Accipitriformes

Familia

Accipitridae

Género

Circus

Distribución y hábitat

The long-winged harrier's year-round range encompasses most of eastern South America, including eastern Argentina, Uruguay, Brazil and Paraguay, and extends up to Colombia, Venezuela, and the northern tips of Guyana, Suriname and French Guiana. The species has also been observed occasionally in extant areas such as Bolivia, Peru, Chile, Trinidad and Tobago, and all the way down to Tierra del Fuego in southern Argentina. It is vagrant to Panama and the Falkland Islands.<p>This species occupies large grasslands and agricultural fields, where their wide-range active hunting technique is very effective. Their habitat also includes savanna, marshes and wetlands of South America.

Migración

Migrantes completos

Comportamiento

Patrón migratorio: Migrantes completos.

Conservación

Tendencia poblacional: en declive.

Tendencia poblacional

en declive