Redstart – Phoenicurus phoenicurus
or often simply redstart, is a small passerine bird in the redstart genus Phoenicurus. Like its relatives, it was formerly classed as a member of the thrush family, (Turdidae), but is now known to be an Old World flycatcher (family Muscicapidae). The common redstart shows some affinity to the European robin in many of its habits and actions. It has the same general carriage, and chat-like behaviour, and is the same length at 13–14.5 cm long but slightly slimmer and not quite as heavy, weighing 11–23 g. The orange-red tail, from which it and other redstarts get their names (“start” is an old word for “tail”), is frequently quivered. Among common European birds, only the black redstart (Phoenicurus ochrurus) has a similarly coloured tail.

The male in summer has a slate-grey head and upperparts, except the rump and tail, which, like the flanks, underwing coverts and axillaries are orange-chestnut. The forehead is white; the sides of the face and throat are black. The wings and the two central tail feathers are brown, the other tail feathers bright orange-red. The orange on the flanks shades to almost white on the belly. The bill and legs are black. In autumn, pale feather fringes on the body feathering obscures the colours of the male, giving it a washed-out appearance. The female is browner, with paler underparts; it lacks the black and slate, and the throat is whitish.

It sounds like this
Recording by Teet Sirotkin from Xeno canto