Wallcreeper

The wallcreeper is a small passerine of the high mountains of the Palearctic from southern Europe to central China. Its plumage is primarily blue-grey with darker flight and tail feathers. In summer males have a black throat grading into the grey, and females may have a white throat or a small dark patch; in autumn and winter both sexes have a white throat. The tail is short and black with a narrow white fringe (Wikipedia, general species account).

It breeds at 1,000–3,000 m in Europe, 2,800–4,000 m in the Tien Shan and 3,600–5,100 m in the Himalaya. The female usually lays four or five eggs and incubates them for 19–20 days, fed regularly by her mate. Though largely silent, both sexes sing, the females generally only while defending feeding territories in winter; the song is a high-pitched, drawn-out whistle of alternately rising and falling notes. Wallcreepers are territorial and pairs vigorously defend their breeding territory in summer (Wikipedia, general species account).