Picathartes
The picathartes, rockfowl, or bald crows are a small genus of two passerine bird species forming the family Picathartidae found in the rain-forests of tropical west and central Africa. They have unfeathered heads, and feed on insects and invertebrates picked from damp rocky areas. Both species are totally non-migratory, being dependent on a specialised rocky jungle habitat.[1]Both species are listed as vulnerable to extinction on the IUCN Red List.
The taxonomic position of the clade and its two species has been confusing. At various times, it has been grouped with the babblers, flycatchers, starlings, crows and others before being placed in a family of its own.[2] Serle in 1952 thought it resembled the Asian genus Eupetes while Sibley used egg-albumin protein similarity, determined by electrophoresis, to suggest that it belonged to the Timaliidae. Olson revived the idea that it was related to Eupetes in 1979.[3] A molecular sequence based study suggests that it may indeed be closely related to the crows and placed somewhere at the boundary between the Passerida and Corvida.[4] More specifically they appear to be a sister of the rockjumpers (Chaetops) and are basal to the clade containing the Sylvioidea, Passeroidea and Muscicapoidea but outside the core Corvoidea.[5]
This generic name comes from a combination of the Latin genera pica for "magpie" and cathartes for "vulture".[6]
A possible third species may exist in Uganda, in the vicinity of the Kazinga Channel, linking Lake Edward with Lake George.[7]
The picathartes are large (33–38 centimetres (13–15 in) long) passerines with crow-like black bills, long neck, tail, and legs. They weigh between 200–250 grams (7.1–8.8 oz). The strong feet and grey legs are adapted to terrestrial movement, and the family progresses through the forest with long bounds on the ground. The wings are long but are seldom used for long flights. The plumage is similar between the two species, with white breasts and bellies and darker (grey and grey-black) wings, backs, and tails. The neck color varies between the two species, giving them their individual names (grey-necked and white-necked picathartes). They also have bald heads with brightly coloured and patterned skin.[1]
Rockfowl are generalised feeders, taking a wide range of invertebrate prey. Prey items include a range of insects, particularly beetles, termites, and ants, as well as millipedes, centipedes, earthworms, and gastropods. Frogs and lizards are also taken, but these are mostly fed to their chicks. Prey is taken both by foraging on the ground and in the trees. They will also forage in shallow flowing water for crabs. When foraging on the ground, they move forward with hops and bounds, then pausing to search for prey. The longish bill is used to turn over leaves and seize prey, but the feet are never used for either. Both species will follow swarms of ants in order to snatch prey fleeing the ants.[1]
