About Tarsiger cyanurus (Pallas, 1773)
The red-flanked bluetail (scientific name: Tarsiger cyanurus (Pallas, 1773)) measures 13–14 cm in length and weighs 10–18 g. It is similar in size and weight to the common redstart, and slightly smaller—especially with a slimmer build—than the European robin. As its name suggests, both sexes have a blue tail and rump, along with orange-red flanks, a white throat, and greyish-white underparts. It also has a small, thin black bill and slender black legs. Adult males additionally have dark blue upperparts, while females and immature males are plain brown on their upperparts aside from the blue rump and tail, and have dusky breasts. In terms of behavior, the red-flanked bluetail is similar to the common redstart: it frequently flicks its tail in the same way, and regularly flies from a perch to catch insects in the air or on the ground. Males sing a melancholy trill from treetops, and its call is a typical chat "tacc" sound. It builds its nest on or near the ground, and clutches contain 3–5 eggs that are incubated by the female. The red-flanked bluetail breeds in mixed coniferous forests with undergrowth, found across northeastern Europe from northern Sweden east across Siberia to Kamchatka, and south to Japan. It winters mainly in southeastern Asia, the Indian subcontinent, the Himalayas, Taiwan, and northern Indochina. Its breeding range is slowly expanding westward through Finland, where up to 500 pairs now breed. It is a rare but increasing vagrant to Western Europe, occurring mainly in Great Britain. There have also been a small number of records in North America: most are from western Alaska, with one additional record from San Clemente Island off the southern California coast, one overwintering on the Central California coast in Santa Cruz, California in 2023, and another spotted in New Jersey in December 2023.
