acitli.

Ā-CIH-TLI, Western Grebe/Clark’s Grebe (Aechmophorus occidentalis/A. clarkii) [FC: 31 Acitli] “It is also rare…. It comes when the various [water] birds come. Its head is quite small, black, with a pointed, chili-red bill. Its eyes are like fire. It is long-necked. Its body is small and straight, small and thick: its breast very white, its back black…. Its legs black: they are also somewhat toward its rump, like a duck’s legs. It lives there in the lagoon….” Martin del Campo identifies this bird as the Western Grebe. Since he wrote, this grebe has been split into two closely allied species, The Western Grebe and the Clark’s Grebe. The relative abundance of these two species in the central Mexican highlands is still unclear, though it is reasonable to assume that the Aztecs treated them as one. The name might be interpreted as “water hare” or “water grandmother” (cf. Karttunen 1983:34), though neither is made explicit in the original account.
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analysis here also appearing in E. S. Hunn, "The Aztec Fascination with Birds: Deciphering Sixteenth-Century Sources," unpublished manuscript, 2022, cited here with permission.

the western grebe (a bird)
Henry M. Reeves, "Once Upon a Time in American Ornithology," The Wilson Journal of Ornithology 119:2 (June 2007), 317.