iztaccuauhtli.

IZTAC-CUĀUH-TLI, litearlly, “white eagle/hawk,” White-tailed Hawk (Buteo albicaudatus) [FC: 40 Iztac quauhtli] “It has scant, ashen [feathers]; it lacks down; it is very chalky. The bill is yellow, the legs are yellow.” This name might apply to a variety of large diurnal raptors. The White Hawk (Leucopternis albicollis) is nearly pure white but has a dark bill, while the White-tailed Hawk is white below and on the tail, with yellow bill and legs. Both are large hawks, though the White-tailed ranges more widely, notably in highland areas of northern and central Mexico (Howell & Webb).
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); Steven N. G. Howell and Sophie Webb. A Guide to the Birds of Mexico and Northern Central America (Oxford University Press, Oxford, New York, Tokyo, 1995); 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analysis here also appearing in E. S. Hunn, "The Aztec Fascination with Birds: Deciphering Sixteenth-Century Sources," unpublished manuscript, 2022, cited here with permission.