cuachilli.

CUACHIL-LI/CUACHIL-TON, Common Gallinule (Gallinula galeata) [FC: 27 Quachilton] “It lives on the water; it belongs with the ducks. Its head is chili-red, its bill pointed. It lives, it is hatched only here, among the reeds.” Martin del Campo identified this bird as the American Coot (Fulica americana). However, I suspect the description better fits the coot’s close relative, the Common Gallinule, which sports a conspicuous red frontal shield. The coot, by contrast, shows only a rather obscure purplish bump on its white bill. See also YACA-CIN-TLI, the American Coot.
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analysis here also appearing in E. S. Hunn, "The Aztec Fascination with Birds: Deciphering Sixteenth-Century Sources," unpublished manuscript, 2022, cited here with permission.

ma ticcohuacan yn tetl. yn quahuitl. ma yehuatl yca. yn atlan chaneque yn atlan onoque ӯ michin yn axollotl yhuan in cueyatl. yn acocillin. yn anenez yn acohuatl. yn axaxayacatl. yn izcahuitli. yhuan yn canauahtli yn quachilli = yn yacaçintli. yn ixquich yn totome yn atlan chaneque = Let us buy stone and wood by means of water life, the fish, salamanders, frogs, crayfish, dragonfly larvae, water snakes, waterfly eggs, and red shellfish that live in the water; and the ducks, American coots, all the birds that live in the water. (central Mexico, early seventeenth century)
Codex Chimalpahin: Society and Politics in Mexico Tenochtitlan, Tlatelolco, Culhuacan, and Other Nahuatl Altepetl in Central Mexico; The Nahuatl and Spanish Annals and Accounts Collected and Recorded by don Domingo de San Antón Muñón Chimalpahin Quauhtlehuanitzin, eds. and transl. Arthur J. O. Anderson and Susan Schroeder (Norman: University of Oklahoma Press, 1997), vol. 1, 106–107.