The Northern Wren is very small bird, much smaller than Sparrow. The exterior of Wren is very specific: it is stocky large-headed bird rufous-brown above barred with dark-brown and grey, even on wings and tail; and with short stump-tail. The bill is dark brown, the legs pale brown. The seasonal, age and sex variation of plumage is insignificant. But juveniles in first plumage are distinguished by rufous-red tinge on upperparts (adults are rufous-brown above), the head feathers are pale-brown with dark edges on tips (adults lack these edges), light supercilium is faint, the belly and flanks are faintly barred. It is very mobile, sticks the dense bushes and windfalls low or on the ground. Its movements are incessant rather than rapid; its flights swift but short. Weight 7-12 grams, length 9-11, wing 4,5-5,2, wingspan 15-17 cm.
The Northern Wren lives resident in places of its nesting, common everywhere. Inhabits light spruce forest with plenty of wind-fallen trees and branches, thick undergrowth, boulders and stone crumbles at 1500-2600 m. In Talasskiy Alatau one brood was recorded at 3000 m in rocks of alpine belt. In autumn and winter on dispersal occurs in deciduous and riparian forests, gardens, in reed beds and tall weeds near streams. Spring movement occurs from March to early April. Separate pairs form after males attract females to beforehand built nests. As a rule, a male constructs several half-finished nests located under turf ledge of bank, between roots, in rock cracks, spruce trees or in human buildings. Nests are made of dry twigs and grass. After the female chooses the nest she settles the scoop lining it with plenty of hair and feathers. Clutches of 4-6 eggs appear from first half of May to mid of July. Female incubates for 15-17 days and feeds the brood. Males deliver food to females but never get in the nest. If one of parents die, the other continues to feed juveniles to fledging age (16-18 days) from mid of June to the first half of August. Polygamy has not been proved in tianschanicus. Double brooded, repeated breeding after loss of eggs or juveniles is common (up to four attempts have been recorded). Autumn movement begins early in September to October, one by one or in small groups.
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