ayopalhuitzilin.

AYOPAL-HUĪTZIL-IN, literally, "purple dye hummingbird," perhaps the Violet-crowned Hummingbird (Amazilia violiceps) [FC: 24 Aiopalhujtzili] “… is light brown, the color of tunas {fruits of the prickly pear cactus}.” Martin del Campo identified this hummingbird as the Heloise, now Bumblebee, Hummingbird (Selasphorus heloisa). However, the sparce description does not support his identification. the combination of light brown and purple could describe the gray-brown back and violet-blue crown of the Violet-crowned Hummingbird, a common resident of the central Mexican highlands. See also HUĪTZIL-IN, hummingbird.
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analysis here also appearing in E. S. Hunn, "The Aztec Fascination with Birds: Deciphering Sixteenth-Century Sources," unpublished manuscript, 2022, cited here with permission.

Note that the color, ayopalli, is a difficult one to translate.