Willow tit

The willow tit (Poecile montanus) is a passerine bird in the tit family, Paridae. It is a widespread and common resident breeder throughout temperate and subarctic Europe and across the Palearctic. The plumage is grey-brown and off-white with a black cap and bib. It is more of a conifer specialist than the closely related marsh tit, which explains its breeding much farther north. It is resident, and most birds do not migrate.

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".

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).

There are 14 recognised subspecies:

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.

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.

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.

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.