Pionus is a genus of medium-sized parrots native to Mexico, and Central and South America. Characteristic of the genus are the chunky body, bare eye ring (which can vary in color), and short square tail. They are superficially similar to Amazon parrots, but smaller and in flight their wing-strokes are far deeper. Coloration is generally subdued yet complex compared to member species of the genus Amazona; under bright lighting, their feathers shimmer with iridescent brilliance. All species share bright red undertail coverts; the scientific name of one species, the blue-headed parrot (P. menstruus), refers to this. Males and females are similar, with no notable sexual dimorphism.