Picotelle à gorge blanche

Identification

The white-throated treerunner is 15–16 cm (5.9–6.3 in) long on average, with a weight between 20–27 grams (0.71–0.95 oz). It has an appearance reminiscent of the nuthatch, with its overall look and plumage, unlike other species in the Furnariidae. Wing chord is from 76–86 mm (3.0–3.4 in), tail is 52–65 mm (2.0–2.6 in), and torso from 20–23.7 mm (0.79–0.93 in). The iris is dark brown. It has a long beak, at around 16–23.8 mm (0.63–0.94 in) with a slight upward curve. Its upper mandible is dark gray and lower mandible a whitish-pale gray. The feet are dark gray, blackish or brown.<p>The species is easily recognized by its white throat, contrasting with its upper parts. Its face is blackish-brown and slightly darker than its head crown, which is a dull brown. The back is a paler chestnut-brown, pulling against the red rump and tail. The wing coverts are dark brown, with red or chestnut brown on the feather edges and tail end. The primaries are darker, the remiges black-brown with light edges and inner primaries marked with a short, light red wing bar. The tail is rounded, with rigid rectrices with shortened barbs ending in small spines up to 9 mm (0.35 in) long.<p>A large white zone covers the treerunner's cheek and throat, descending to the middle of the chest. The rest of the lower parts, to the undertail coverts, are made up of white feathers largely bordered with dark brown, giving an irregularly spotted appearance. Both sexes of adults look similar. The chick is distinguished by an ochre-striped crown and back, and often with blackish borders on the throat feathers.

Taxonomie

The white-throated treerunner was scientifically described in 1831 under the protonym Dendrocolaptes albogularis by the British explorer Phillip Parker King, who visited Patagonia and Tierra del Fuego among other places. The specific name, albogularis, means "white-throated" in Latin; the type locality is not known but is supposed to be the Strait of Magellan. In 1837, the Argentine zoologist Hermann Burmeister removed the species from the genus Dendrocolaptes, which today includes only five species of climbers, and assigned it a separate genus, Pygarrhichas, giving it the novel specific name of "ruficaudis" (from Latin meaning "red-tailed"). Burmeister constructs this name from the ancient Greek πυγη (pugē) meaning "rump" and αρριχος (arrhikhos) denoting wicker, to refer to the stiffness of the bird's tail helping it progress along trunks.<p>In 1839, English ornithologist John Gould, presumably unaware of King's work, independently described the species in Zoology of the Voyage of H.M.S. Beagle as Dendrodramus leucosternus (from the ancient Greek for "white-bellied"). He observed the species on the Chiloé Island, and found similarities with the Eurasian treecreeper (Certhia familiaris) in its behavior. In 1890, English zoologist Philip Lutley Sclater placed this genus in the now obsolete family Dendrocolaptidae, a position changed by paleornithologist Alan Feduccia in 1973 who placed the genus in its current family, Furnariidae. According to the International Ornithological Congress and Alan P. Peterson, no subspecies is distinguished.<p>In 1839, Gould mentions that English zoologist George Robert Gray would relate the white-throated treerunner to the genus Dendroplex described by English ornithologist William John Swainson. In the 2003 Handbook of the Birds of the World, Volume 8, American ornithologist James Van Remsen Jr. explains that while P. albogularis is traditionally related to the Xenops sittines and other tree-bark gleaning Furnariidae, plumage and biogeography suggest that these different species are not directly related and that their similarities are merely the result of convergent evolution. It has also been suggested that similarities in plumage and foraging behavior may bring the white-throated treerunner closer to Synallaxis of the genus Aphrastura.<p>Two molecular phylogenies of the family published in 2009, and then one in 2011, negate such relatedness and clarify the evolutionary history somewhat while implying significant classification changes. The naming of a subfamily (that of "Pygarrhichinae") or tribe (that of "Pygarrhichini", within the subfamily Furnariinae) is advanced for a clade that would include the white-throated treerunner, the rufous-tailed xenops (Microxenops milleri), species of the genus Ochetorhynchus, and would absorb the band-tailed Eremobius (O. phoenicurus) as well as the crag chilia (O. melanurus), previously placed in the monotypic genera Eremobius and Chilia respectively.<p>

Nom scientifique

Pygarrhichas albogularis

Autorité

(King, PP, 1831)

Ordre

Passériformes

Famille

Furnariidés

Genre

Pygarrhichas

Répartition et habitat

This species lives in central and southern Chile and western Argentina, from Santiago and Mendoza to Tierra del Fuego. It is found in the south of its distribution in the southernmost forest in the world, on Horn Island. It lives from sea level to 1,200 m of altitude, populating forests with large trees, whether dense or not, but avoiding young forests. The white-throated treerunner seeks out forests dominated by "false beech" species of the genus Nothofagus. It exploits the trunks at mid-height of trees up to the top of the canopy as a small woodpecker would. The species is sedentary, but can be erratic outside the breeding season.

Migration

Espèce sédentaire

Comportement

Mode de migration: Espèce sédentaire.

Conservation

Tendance de la population: en déclin.

Tendance de la population

en déclin