The Siberian accentor (Prunella montanella) is a small passerine bird that breeds in northern Russia from the Ural Mountains eastwards across Siberia. It is migratory, wintering in Korea and eastern China, with rare occurrences in western Europe and northwestern North America. Its typical breeding habitat is subarctic deciduous forests and open coniferous woodland, often close to water, although it also occurs in mountains and spruce taiga. It inhabits bushes and shrubs in winter, frequently near streams, but may also be found in dry grassland and woods.
The Siberian accentor has brown upperparts and wings, with bright chestnut streaking on its back and a greyish-brown rump and tail. The head has a dark brown crown and a long, wide pale yellow supercilium ("eyebrow"). All plumages are quite similar. The nest is an open cup in dense shrub or a tree into which the female lays four to six glossy deep blue-green eggs that hatch in about ten days. Adults and chicks feed mainly on insects, typically picked off the ground, but sometimes taken from vegetation. In winter, the accentors may also consume seeds or feed near human habitation.
Breeding over a huge area, the Siberian accentor has a large and stable population. It is therefore evaluated as a species of least concern by the International Union for Conservation of Nature (IUCN), although, as a northern breeding species, it may be affected by climate change in the long term. October and November 2016 saw an unprecedented influx of this species into western Europe, reaching as far as the United Kingdom.
Taxonomy
The accentors are a family of small ground-living insectivorous birds, most of which are found in mountainous habitats in Eurasia, although the dunnock is a lowland species. Their relationships with other bird families are uncertain. All accentors are placed in a single genus, Prunella, but within that genus, the Siberian accentor is most similar in appearance to the black-throated, brown, Kozlov's, Radde's and Arabian accentors. These are of comparable size and typically have a pale supercilium and dark markings on the head or throat. However, a 2013 phylogenetic study indicates that the closest relative of the Siberian accentor is actually the physically dissimilar Japanese accentor.
On his return from his pioneering expedition to central and eastern Russia in 1768–1774, the Russia-based German zoologist Peter Simon Pallas formally described the Siberian accentor in 1776 as Motacilla montanella. The accentors were moved to their current genus by French ornithologist Louis Jean Pierre Vieillot in 1816.
The Siberian accentor has two subspecies: Prunella montanella montanella, (Pallas, 1776), the nominate subspecies, breeds in northern Russia from just inside Europe eastwards to the Lena River. It also occurs further south, from the Ob to the Amur. Prunella montanella badia, Portenko, 1929, breeds in northeastern Siberia eastwards from the Lena, and south to the Sea of Okhotsk.
"Accentor" comes from the old scientific name for the Alpine accentor, Accentor collaris. It derives from Late Latin and means "sing with another" (ad + cantor). The genus name Prunella is from the German Braunelle, "dunnock", a diminutive of braun, "brown", and the specific montanella is a diminutive of Latin montanus, "mountain".
Description
The Siberian accentor is on average long and weighs . The adult of the nominate race has brown upperparts and wings, with bright chestnut streaking on its back and a greyish-brown rump and tail. There are two narrow whitish bars on the folded wings. The head has a dark brown crown, a long, wide pale yellow supercilium, a blackish patch behind the eye and grey sides to the neck. The underparts are ochre yellow, becoming strongly buff on the flanks and greyish on the lower belly. There are rich chestnut streaks on the sides of the breast and the flanks. The iris is a warm red-brown, the sharply pointed bill is dark and the legs are reddish.
All plumages are similar. The female has slightly duller underparts with weaker streaking, and the juvenile is overall duller with brown spots on the breast and chest. Juvenile birds in autumn also show more wear to the tail feathers and the tertials that cover the folded wing, and they often have a duller iris colour than the adults. The subspecies P. m. badia is somewhat smaller and darker than the nominate form, with richer brown upperparts, deeper buff underparts, and rustier flank streaks.
Adults undergo a complete moult between July and September after breeding has finished. Juvenile birds have a partial moult in the same period, replacing the head, body and some wing covert feathers.