Common Redstart

The common redstart resembles the European robin in many habits and carriage, with the same chat-like behaviour, and is the same length at 13–14.5 centimetres but slightly slimmer, weighing 11–23 grams. Its orange-red tail, from which redstarts get their name ('start' being an old word for tail), is frequently quivered. Among common European birds only the black redstart has a similarly coloured tail. (Wikipedia, general species account)

The common redstart prefers open, mature birch, oak or, particularly in the north, conifer woodland with high horizontal visibility and little shrub and understorey, especially where the trees are old enough to hold nesting holes. It also uses orchards, villages, parks and old gardens. Nests are built in cavities such as natural tree holes, so dead trees or those with dead limbs benefit it, and nestboxes are commonly used. In Britain it is mainly found in upland areas less affected by farming intensification. (Wikipedia, general species account)