The bird is a little smaller than a sparrow. Body length is 15–17 cm, wingspan 22–24 cm, weight 15–20 g.
The birds in the spring plumage are characterized by a dark brown hat on their heads, the edges of which are darker and form a blackish strip above the eyebrow, a wide, dark brown strip (“mask”) tapering towards the beak passes through the cheek through the eye. Between the cap and the mask, a light ocher-yellow eyebrow is clearly distinguished, which sometimes can look almost white. The throat and chest are buffy-yellow, and there are usually rare blackish, blurry spots on the chest. The belly is colored more lightly, along the sides of the body are longitudinal streaks of reddish-brown color. The sides of the neck are gray. The upper body is reddish brown; longitudinal dark streaks are found on the back. The beak is dark-colored, at the base of the mandible there is a yellowish spot (less noticeable than that of the alpine curler). The legs of the bird are brown, and the eyes are reddish-brown. The male and the female are similar to each other, the latter has a less red tint in the color of the back, and the black stripe along the edge of the cap above the eyebrow is narrower, blackish spots on the chest are less pronounced.
Adult birds have one full post-breeding molt in a year. In autumn, in the fresh plumage of birds, the chest, throat and eyebrow are more saturated with a red color, the hat and mask, on the contrary, are lighter, the speckles on the back are more contrasting, the black spots on the chest are brighter, on the feathers of the feather there are light ocher edges.
In juvenile attire, young birds are similar to adults, but on top they have a smaller red color, the hat and mask are much lighter, the head is duller and not so contrasting, gray is almost not pronounced on the neck, large dark spots are clearly visible on the chest and sides of the throat . From August to mid-September, young birds partially molt, after which they practically do not differ in the color of their plumage from adult birds.
Males often sing on tops of trees or bushes. The song is very similar to the song of the forest curler [2] and is an iridescent, thin, "silver" trill lasting 2-4 seconds. There is evidence that the signal “fuity” emitted between songs is characteristic of the Siberian curler [3] [4] .
Range of species: nesting is marked in yellow, winter - in blue
Breeding Migratory View. The breeding range covers mainly the territory of northern Asia; west of the Urals, the species is found in the northern taiga until about Pechora, where it is considered rare. Winters in Korea and East China [5] [6] . Autumn flights are known in the middle lane of the European part of Russia. Rare single flights of the species in winter to Japan are known [2] .
Birds inhabit a variety of dense forests and thickets of shrubs, most often with the presence of spruce and fir. They feed mainly on insects and seeds [4] . Bird chicks are fed mainly by insects with the addition of seeds. Food is collected on the ground, less commonly on trees and bushes.
Monogamous look. The breeding season is from June to August. Nests are arranged low above the ground, mainly on a Christmas tree or fir. At the nest, the birds behave very secretively, silent. The nest is quite dense, neatly folded, deep. During its construction, a lot of green moss, twigs, blades of grass, lichens are used; the lining usually consists of wool and stalks of moss [3] . The egg is blue, without a pattern. In clutch usually 4-7 eggs. Only the female incubates, and both parents feed the offspring [4] . In the southern part of the range, two broods may appear per season, in the northern - only one [3] .
