The rufous-tailed hummingbird (Amazilia tzacatl) is a medium-sized hummingbird in the "emeralds", tribe Trochilini of subfamily Trochilinae. It is found from east-central Mexico through Central America and Colombia into Ecuador and Venezuela. Taxonomy The rufous-tailed hummingbird was formally described in 1833 by the Mexican naturalist Pablo de La Llave. He placed it in the genus Trochlilus and coined the binomial name Trochilus tzacatl. The rufous-tailed hummingbird is now placed in the genus Amazilia that was introduced in 1843 by the French naturalist René Lesson. The genus name comes from the Inca heroine in Jean-François Marmontel's novel Les Incas, ou la destruction de l'Empire du Pérou. The specific epithet is from Aztec mythology: Tzacatl was a warrior chief. The rufous-tailed hummingbird has these five recognized subspecies: A. t. tzacatl (La Llave, 1833) A. t. handleyi Wetmore, 1963 A. t. fuscicaudata (Fraser, 1840) A. t. brehmi Weller & Schuchmann, 1999 A. t. jucunda (Heine, 1863) A. t. handleyi was originally described as a separate species, the Escudo hummingbird. At least one author treated the rufous-tailed hummingbird and the chestnut-bellied hummingbird (Saucerottia castaneiventris) as a superspecies; the latter was included in genus Amazilia at that time, but the two are now known to not be closely related. Some authors have doubted that A. t. fuscicaudata should be a separate subspecies. Description The rufous-tailed hummingbird is long and weighs approximately . The adult male of the nominate subspecies has a green head and upperparts except for chestnut-brown lores and uppertail coverts. The tail is also mostly chestnut-brown, giving the species its English name; the feathers' outer webs and tips are bronze green. The throat, upper breast, and sides are green; the throat feathers sometimes have thin white edges giving a scalloped effect. The lower breast is gray, the belly white, and the undertail coverts chestnut-brown. The adult female's lower breast is a paler gray than the male's and the scalloping on the throat is more pronounced. Juveniles have a cinnamon wash to the lower breast and sides and the feathers of the lower back and rump have narrow cinnamon tips. The outer half of the bill's maxilla is black and the inner half red; the mandible is red with a black tip. The song is "varied, high, thin, squeaky chirping, tsi, tsi-tsi-tsit tsi-tsitsi tsi-si-si." Its calls are "a fairly hard, smacking tchik-tchik...or...tchi tchi..., at times repeated insistently" and "dry, hard chips often run into