Mésange des saules

Identification

The willow tit is 11.5 cm (4.5 in) in length, has a wingspan of 17–20.5 cm (6.7–8.1 in) and weighs around 11 g (0.39 oz). It has a large head, a thin bill, a long dull black cap that descends to the mantle and a black bib. The sides of the face are white, the back is grey-brown and the underparts are buff. The sexes are similar in appearance.<p>In the east of its range it is much paler than marsh tit, but as one goes west the various races become increasingly similar, so much so that it was not recognised as a breeding bird in Great Britain until the end of the 19th century, despite being widespread.<p>The willow tit is distinguished from the marsh tit by a sooty brown instead of a glossy blue black cap; the general colour is otherwise similar, though the under parts are more buff and the flanks distinctly more rufous; the pale buff edgings to the secondaries form a light patch on the closed wing. The feathers of the crown and the black bib under the bill are longer, but this is not an easily noticed character.<p>The commonest call is a nasal zee, zee, zee, but the notes of the bird evidently vary considerably. Occasionally a double note, ipsee, ipsee, is repeated four or five times.

Taxonomie

The willow tit was described in 1827 by the Swiss naturalist Thomas Conrad von Baldenstein under the trinomial name Parus cinereus montanus. The type locality is the mountain forests in the Canton of Grisons, Switzerland. The willow tit is now placed in the genus Poecile that was erected by the German naturalist Johann Jakob Kaup in 1829. The genus name, Poecile, is the Ancient Greek name for a now unidentifiable small bird, and the specific montanus is Latin for "of the mountains".<p>Poecile was at one time treated as a subgenus within the genus Parus but molecular taxonomic analysis, using both nuclear and mitochondrial genes, supports Poecile as a distinct clade. Within Poecile, most of the Old World species (including the willow tit) form a separate clade from the New World chickadees. The taxonomic analysis has shown that the willow tit is sister to the Caspian tit (Poecile hyrcanus).<p>There are 14 recognised subspecies:<p>The Sichuan tit (Poecile weigoldicus) was formerly treated as a subspecies of the willow tit. It was promoted to species status based on a 2002 phylogenetic analysis that compared DNA sequences from the mitochondrial cytochrome-b gene. The single locus results were later confirmed by a larger multi-locus analysis published in 2017.

Nom scientifique

Poecile montanus

Autorité

(Conrad von Baldenstein, 1827)

Ordre

Passériformes

Famille

Paridés

Genre

Poecile

Répartition et habitat

Migration

Vertical migration

Comportement

The willow tit excavates its own nesting hole, even piercing hard bark; this is usually in a rotten stump or in a tree, more or less decayed. Most nests are cups of felted material, such as fur, hair and wood chips, but feathers are sometimes used. The eggs are laid daily. The clutch is typically between six and nine eggs. The eggs have a white background and are marked with red-brown speckles and spots which are often concentrated at the broader end. They measure around 15.8 mm × 12.3 mm (0.62 in × 0.48 in) and weigh 1.2 g (0.042 oz). The eggs are incubated by the female alone and hatch after 13–15 days. The chicks are then cared for and fed by both parents but only the female broods the young. The nestlings fledge after 17–20 days. Only a single brood is raised each season.<p>In a study using ring-recovery data carried out in northern Finland, the survival rate for juveniles for their first year was 0.58, and the subsequent adult annual survival rate was 0.64. For birds that survive the first year the typical lifespan is thus only three years. The maximum recorded age is 11 years; this has been recorded for a bird in Finland and for another near Nottingham in England.<p>Birds feed on insects, caterpillars, and seeds, much like other tits. This species is parasitised by the moorhen flea, Dasypsyllus gallinulae.

Conservation

Tendance de la population

declining