Picathartidae Rockfowl
Version: 1.0 — Published March 4, 2020
Introduction
In the forests of western Africa live two species of large songbirds, whose long-necked, long-tailed, and long-legged profiles hint at their affinities to the equally enigmatic Rail-babbler, a continent away. Unlike their relative, however, these birds sport naked heads decorated with large colorful patches. Their English common name derives from their predilection for building their nests high on a cave or cliff wall. Asymmetric sexual selection is apparently not the cause of their bizarre appearance, as the sexes are similar and the pair dutifully raise their one to three chicks together. Rockfowl use their long legs to bound and hop along the forest floor, turning over leaves in search of prey, and at times leaping upwards to grab insects from overhanging vegetation.
Habitat
Rockfowls inhabit lowland and mid-elevation rainforests where they can find either caves or sheltered cliffs for nest sites and slow streams with muddy banks for nesting material. Picathartids are most frequent in forest patches with dense leaf litter and army ants, and they can tolerate disturbed forest and second-growth.
Diet and Foraging
Picathartids feed primarily on insects and other invertebrates, such as earthworms and crabs, as well as small vertebrates, including fish, lizards, and frogs. They forage on the ground, and even in streams, but are also not averse to foraging high in trees. They quite often follow army ant swarms, capturing prey that are struggling to escape.
Breeding
Picathartids are monogamous with biparental care. They sometimes breed colonially, with up to 40 pairs at a single site if nest sites elsewhere are limited. More frequently, only one or two nests are located at a single site. The nests are mud cups that are reinforced with leaves, twigs, and grass incorporated into the mud and lined with dry vegetation; these are attached to vertical rock wall surfaces on cliffs or in caves. Females lay 1 to 3 eggs, although 2 is the most common clutch size. Both males and females are active in incubation and in feeding the chicks. Incubation takes 17 to 28 days, with 20 days being most common, and the nestlings leave the nest at 23 to 29 days post-hatch.
Conservation Status
Both White-necked and Graynecked Rockfowl (Picathartes gymnocephalus and P. oreas, respectively) are of conservation concern (2 VU). Populations have declined in recent years as a result of continuing habitat fragmentation due to forest clearing for agriculture, timber, and charcoal production. The highly scattered and sparse distributions of both species suggest small population sizes with limited capacity to absorb further habitat modification.
Systematics History
The rockfowls form part of a small clade of loosely allied oscine passerines we call the “basal passerid oscines.” They were previously grouped with highly divergent families including Corvidae, Timaliidae sensu lato, and Sylviidae sensu lato, but recent molecular phylogenetic studies have shown that the rockfowls are only distantly related to these other groups, and at least two studies suggest that Picathartidae is sister to all the other Passerida, either including Petroicidae (Barker et al. 2004, Beresford et al. 2005) or not (Irestedt & Ohlson 2008, Barker 2014). Another study concentrating on the corvoids indicates that Picathartidae is sister to a clade that includes Petroicidae and other Passerida (Aggerbeck et al. 2014). Still, it must be remembered that these “basal passerid oscines” do not necessarily have very much stronger relationships to Passerida than they do to Corvoidea, as one study suggests that Picathartidae is sister to the corvoids (Shepherd & Lambert 2007). The relatively few studies that have included Chaetopidae, Eupetidae, and Picathartidae indicate that Picathartidae is sister to the clade made up of Eupetidae and Chaetopidae together (Jønsson et al. 2007, Jønsson et al. 2011), and other studies lacking Eupetidae indicate a sister relationship for Picathartidae with Chaetopidae (Beresford et al. 2005, Irestedt & Ohlson 2008).
Conservation Status
Least Concern |
0%
|
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Near Threatened |
50%
|
Vulnerable |
50%
|
Endangered |
0%
|
Critically Endangered |
0%
|
Extinct in the Wild |
0%
|
Extinct |
0%
|
Not Evaluated |
0%
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Data Deficient |
0%
|
Unknown |
0%
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Data provided by IUCN (2023) Red List. More information