Crax

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Crax is a genus of curassows, large ground-feeding birds found in tropical South America. The great curassow (Crax rubra) ranges as far north as Mexico. Crax birds are known for strong sexual dimorphism: males are brighter and have facial ornaments, and they typically have curly crests and a contrasting crissum (the area around the cloaca).

The genus Crax was introduced by Carl Linnaeus in 1758, with the great curassow designated as the type species in 1897. There are seven Crax species.

Crax is one of the two major lineages of curassows. It likely originated in the Late Miocene. About six million years ago, the ancestral Crax split into northern and southern groups separated by the uplift of the Colombian Andes and the Mérida mountain range. The northern group gave rise to the great, blue-billed, and yellow-knobbed curassows, while the four southern species evolved in the separated landscapes of rising mountains. The distinctive male bill shapes and colors, curly crests, and contrasting crissum are typical of Crax. Members of this genus can hybridize with fertile offspring possible in many pairings.

The name Crax may come from the Greek kras, meaning “head.”