Sitta canadese

Identificazione

The red-breasted nuthatch is a small passerine, measuring 4.5 in (11 cm) in length, with a wingspan of 8.5 in (22 cm) and a weight of 9.9 g (0.35 oz). Its back and uppertail are bluish, and its underparts rust-colored. It has a black cap and eye line and a white supercilium (eyebrow). Sexes are similarly plumaged, though females and youngsters have duller heads and paler underparts.

Tassonomia

In 1760 the French zoologist Mathurin Jacques Brisson included a description of the red-breasted nuthatch in his Ornithologie based on a specimen collected in Canada. He used the French name Le torchepot de Canada and the Latin Sitta Canadensis. Although Brisson coined Latin names for the species, these usually do not conform to the binomial system and none of them are recognised by the International Commission on Zoological Nomenclature. When in 1766 the Swedish naturalist Carl Linnaeus updated his Systema Naturae for the twelfth edition, he added 240 species that had been previously described by Brisson. One of these was the red-breasted nuthatch. Linnaeus included a brief description and used Brisson's name Sitta canadensis as his binomial name.<p>Like all nuthatches, the red-breasted nuthatch is assigned to the genus Sitta (Linnaeus, 1758), a name derived from sittē (σίττη), the Ancient Greek word for the Eurasian nuthatch. The specific epithet canadensis is Neo-Latin for "belonging to Canada". "Nuthatch" is a linguistic corruption of "nuthack", referring to the bird's habit of wedging nuts into cracks in tree bark and hacking at them until they break open. "Red-breasted" is a reference to the rusty colour of the male's underparts.<p>In the past, the red-breasted nuthatch and four other species — the Corsican nuthatch, the Chinese nuthatch, the Algerian nuthatch and the Krüper's nuthatch — were thought to be a single species. These five make up a well-defined species group known as the "Sitta canadensis group", and are sometimes considered to be a superspecies. Within the species group, DNA studies have shown that the red-breasted nuthatch, the Corsican nuthatch and the Chinese nuthatch make up one clade and the Algerian nuthatch and Krüper's nuthatch make up a sister clade. The red-breasted nuthatch is monotypic across its extensive range.

Nome scientifico

Sitta canadensis

Autorità

Linnaeus, 1766

Ordine

Passeriformi

Famiglia

Sittidae

Genere

Sitta

Areale e habitat

Though it is primarily a full-time resident of northern and subalpine conifer forests, the red-breasted nuthatch regularly migrates irruptively, with both the number migrating and the wintering locations varying from year to year. They sometimes reach northern Mexico, where they are rare winter visitors to Nuevo León, Baja California Norte and south along the Pacific slope as far as Sinaloa. In the eastern United States, its range is expanding southwards. Though formerly resident on Isla Guadalupe, an island off the western coast of Mexico, it appears to have been extirpated there, with the last known record of the species on the island dating from 1971. There is a single vagrant record for Mexico's Isla Socorro. It is an extremely rare vagrant to Europe, with two records in the western Palearctic; one bird successfully overwintered in eastern England.

Migrazione

Complete migrants

Conservazione

Because of its large global range and its increasing population, the red-breasted nuthatch is rated as a species of Least Concern by the International Union for Conservation of Nature. In the Americas, it is protected by the Migratory Bird Treaty Act of 1918.

Tendenza della popolazione

rising