The red-flanked bluetail (Tarsiger cyanurus), also known as the orange-flanked bush-robin, is a small passerine bird that was formerly classed as a member of the thrush family Turdidae, but is now more generally considered to be an Old World flycatcher, Muscicapidae. It, and related species, are often called chats.
At 13–14 cm long, the red-flanked bluetail is similar in size and weight to the common redstart and slightly smaller (particularly with a slimmer build) than the European robin. As the name implies, both sexes have a blue tail and rump, and orange-red flanks; they also have a white throat and greyish-white underparts, and a small, thin black bill and slender black legs. The adult male additionally has dark blue upperparts, while females and immature males are plain brown above apart from the blue rump and tail, and have a dusky breast. In behaviour, it is similar to a common redstart, frequently flicking its tail in the same manner, and regularly flying from a perch to catch insects in the air or on the ground. The male sings its melancholy trill from treetops. Its call is a typical chat "tacc" noise. The nest is built on or near the ground, with 3–5 eggs which are incubated by the female.