About Poicephalus cryptoxanthus (W.Peters, 1854)
This species is Poicephalus cryptoxanthus. Its general plumage is green; Sinclair et al. (1993) describe it as "the greenest parrot of the sub-region". The under wing coverts are bright yellow, with variable extent across individuals. The species' specific name derives from this yellow marking: kryptos is Greek for hidden or concealed, and xanthos means yellow. The rump is a very bright, almost metallic green. The margins of underpart feathers share this bright green coloration, which grows more pronounced towards the vent and thighs. The neck is grey-brown; it blends to brown on the head, and to greenish on the mantle. Some individuals have scattered random yellow feathers on the head, neck, and wings. The cause of these extra yellow feathers is unknown, but it has been proposed that they may result from over-vigorous preening by parents. The tail is edged olive-brown and tipped green. Sources disagree on iris color: Maclean (1993) states it is greenish yellow, while Forshaw (1989) describes it as yellow. The legs and feet are blackish grey. The upper bill is dark, almost black, and blends to whitish on the lower bill. Immature birds are consistently described as duller than adults and yellowish on the underparts, per sources including Maclean (1993). Forshaw (1989) describes the species' flight as fast and direct.
