tlehuitzilin.

TLE-HUĪTZIL-IN, a species of hummingbird (Trochilidae) [FC: 25 Tlevitzili]: “its feathers are glistening, resplendent.” Martin del Campo identified this bird as the Allen’s Hummingbird (Selasphorus sasin). However, this is most unlikely, as Allen’s and Rufous Hummingbirds are virtually identical, especially when not males in full adult plumage. There are many other species of local hummingbirds that are far more “resplendent” than the Allen’s, too many to hazard a reasonable guess.
Fr. Bernardino de Sahagún, Florentine Codex: General History of the Things of New Spain; Book 11 – Earthly Things, no. 14, Part XII, eds. and transl. Arthur J. O. Anderson and Charles E. Dibble (Santa Fe and Salt Lake City: School of American Research and the University of Utah, 1963); Rafael Martín del Campo, “Ensayo de interpretación del Libro Undecimo de la Historia General de las Cosas de Nueva España de Fray Bernardino de Sahagún – 11 Las Aves (1),” Anales del Instituto de Biología Tomo XI, Núm. 1 (México, D.F., 1940); and, with quotation selections, synthesis, and analysis here also appearing in E. S. Hunn, "The Aztec Fascination with Birds: Deciphering Sixteenth-Century Sources," unpublished manuscript, 2022, cited here with permission.