Посмотрел в источники, пишут, что на земле, в щелях. Чаще с видом на юг:)
Nest built by female, taking usually 6–8 days, composed of dry herbs and mosses, together with fine grasses and hair, normally placed in sunny site on ground, protected by vegetation, or at base of rock, and exposed to S, but sometimes in shady place, access normally by rocky surface more or less devoid of vegetation; rarely, in crevice in wall or in tree