Members of the
Poicephalus genus are stocky birds with short broad tails and relatively large heads and beaks that often differ in color from their trunks. Although they are parrots with
rectrices of medium length, their
pinion feathers reach down almost to the end of the rectrices, making their wings appear to be remarkably long. According to H. Strunden,
Poicephalus, from
Ancient Greek, means "grey head" (
poliós = grey and
kephalé = head). Most species in the
Poicephalus genus are predominantly green. However, grey is also common, and the feathers on their heads frequently vary in colour from the rest of the plumage. Senegal parrots and brown-headed parrots for example have blackish or dark brown heads, while the head plumage of
brown-necked and Cape parrots is grey-brown to silver-grey. With the exception of the
red-fronted parrot, the different colours of head and body plumage of these four species do not overlap or blend. The red-fronted parrot only shows a more fluent transition, with merely the slate grey ear patches and the red front and crown clearly set apart. Another variation is found in male
Rüppell's parrots, whose brown plumage is overlaid with silver-grey at the ear patches and the top of their heads, with only a tinge of green on the top-side plumage. Female Rüppell's parrots, on the other hand, have a bright blue back section, rump, and upper tail coverts, while the feathers on their lower ventral region and vent are a dull blue. Several of the species show marked
sexual dimorphism, Rüppell's parrots, brown-necked parrots, cape parrots, and
red-bellied parrots are dimorphic, the other species of
Poicephalus parrots cannot be distinguished by the colours of their plumage. The difference is especially clear in red-bellied parrots, where males have red or bright orange plumage on breast, belly and below their wings while the feathers of females are all grey-brown in these areas. The smallest species in the genus is the
Meyer's parrot, with adults reaching a body-length of only 22 centimeters (≈ 8,66 in.) and weighing approximately 120 g (≈ 4,23 oz). The largest species, the
Cape parrot, by contrast, is usually almost as large as an African grey parrot, adult males reaching a size of 32 centimeters (≈ 12,6 in.) and a weight of about 400 g (≈ 14,1 oz). Many
Poicephalus parrots have bulky heads and powerful beaks, the colour of which varying with the species. While
brown-headed parrots and
Niam-Niam parrots have a grey upper mandible and an off-white lower one, other species have a homogeneously grey-coloured beak or a horn-coloured one with a darker tip. The Cape parrot stands out with a particularly sturdy beak in relation to its overall size which it needs to obtain its main food source, the hard-shelled fruit of
Podocarpus trees. British parrot specialist
Rosemary Low has pointed out that, among the genus, only the Cape parrot is able to crack open
walnuts with its beak. Except for
macaws, this is a rare ability among parrots in general. == Distribution ==