CUATEZCA-TL, literally “bald head” [“cabeza despojo”], Purple Gallinule (Porphyrio martinica) [FC: 32 Quatezcatl] “It likewise {as Quapetlaoac } is rare. Also it comes when [the other water] birds come. It is of average size, like a dove <“paloma”>. For this reason, it is called “mirror-head”: on its head is something like a mirror, a round [patch] on the crown of its head. There we appear. On the front of its head is a thin row of feathers, somewhat ashen. Its bill is quite small, cylindrical. Its breast, its back are completely light blue; its wings, its tail are likewise light blue…. Its legs are yellow. And when it swims, when it paddles with its feet in the water, it looks like an ember; it goes glowing, glistening.” Martin del Campo identified this bird as the Purple Gallinule. The description leaves no doubt. The “mirror” on its head corresponds to the pale blue forehead shield.
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analysis here also appearing in E. S. Hunn, "The Aztec Fascination with Birds: Deciphering Sixteenth-Century Sources," unpublished manuscript, 2022, cited here with permission.