White Helmetshrike Prionops plumatus Scientific name definitions

19–25 cm; 25–49 g. Nominate race has extensive elongated (up to 45 mm) crest of greyish-white feathers on mid-crown, shorter (c. 10 mm) crest of whitish spiky feathers on forecrown to lores; hindcrown grey, blackish crescent behind white cheek and ear-coverts (feather pigments on head unstable, and easily washed out with soap); neck and underparts whitish, flanks with blackish smudges (at rest, often concealed by wings); upperparts black, glossed greenish; upperwing black, primaries with broad white central bar (conspicuous in flight), outer five secondaries tipped narrowly white, innermost with broad white tip and outer edge, outermost tertial with broad white tip and outer edge, middle tertial with narrow white outer edge, inner greater and median upperwing-coverts white (white in secondaries, tertials and coverts shows as obvious bar in folded wing); outer tail feathers completely white, inner tail feathers glossy black with white tips, white decreasing in extent towards central two rectrices, which completely black; underwing-coverts and axillaries black; iris dark greenish-grey with yellow outer ring, conspicuous broad orange-yellow orbital ring with scalloped fringe; bill blackish; legs and feet pinkish-orange to red. Sexes similar. Juvenile has shorter crest on mid-crown, no dark crescent behind face, plumage tinged browner, with buff feather tips on upperparts, eyes brown, no orbital ring, legs and feet yellower; adult appearance acquired at c. 12 months. Other races have iris bright yellow; race <em>concinnatus</em> has shorter, forward-curving mid-crown crest (c. 25 mm) and narrower wingbar than nominate; cristatus also has short, forward-curving mid-crown crest, lacks white in secondaries, tertials and upperwing-coverts, has central tail feathers tipped white; <em>vinaceigularis</em> lacks white wingbar, has mid-crown crest even shorter (c. 15 mm) and not distinct from forecrown crest; <em>poliocephalus</em> is small, has white wingbar as broad as nominate but mid-crown feathers as short as preceding race, entire crest from lores to mid-crown uniformly greyish, head greyer than nominate and with darker crescent behind eye, whiter tail.

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Editor's Note: Additional distribution information for this taxon can be found in the 'Subspecies' article above. In the future we will develop a range-wide distribution article.

Breeds mainly in deciduous broadleaf savanna woodlands, including those dominated by Baikiaea, Brachystegia, Burkea, Colophospermum, Combretum, Pterocarpus and Terminalia. In non-breeding season, wanders widely to acacia savanna and other woodlands, coastal and riparian forest and forest edge, lightly wooded grassland, and oil-palm (Elaeis guineensis), eucalypt (Eucalyptus) and pine (Pinus) plantations; also visits gardens, even urban areas. Attracted to recently burnt ground for foraging. To 2200 m; usually below 1500 m, and rare above 1800 m.

Largely resident, but with widespread seasonal movement out of breeding home range, including apparent migrations, e.g. N-S seasonal movement in Ghana, and regular migration (by race poliocephalus) between Kenyan dry season non-breeding grounds and Tanzanian nesting areas. Some movements apparently altitudinal, with descent to lower-lying regions in non-breeding season. In S of range apparently particularly nomadic in dry season, wandering to wooded regions not suitable for breeding and even into urban habitats, e.g. Bulawayo (Zimbabwe). Establishes foraging home ranges on non-breeding grounds and uses traditional roost-sites in leafy trees, e.g. Acacia, Lonchocarpus and Thespia. Also prone to large-scale irruptions associated with major drought periods, e.g. S Africa in 1953, 1970, 1979 and 1992, when large numbers move through and into otherwise unsuitable habitat, e.g highland grasslands to S of main range.

Diet small invertebrates , also small reptiles, and fruit. Among invertebrates , caterpillars account for 46% of items, butterflies and moths (Lepidoptera) 19%, grasshoppers (Acrididae) 7%, termites (Isoptera) 7%, praying mantises (Mantidae) 5%, with ants (Formicidae), beetles (Coleoptera), centipedes (Chilopoda), cicadas (Cicadidae), flies (Diptera) and spiders (Araneae) also represented; small reptiles, mainly geckos (Gekkonidae), form 1% of recorded prey. Identified material in five stomachs contained 42% beetles, 32% ants and 12% grasshoppers. May use auditory cues in prey location. Hunts at all levels, mainly in middle to lower vegetation layers among leaves, branches and twigs, and on ground . In summer hunts primarily in trees, in winter more on ground. In study in Zimbabwe, prey taken on ground and arboreally (from bushes, leaves, trunks, branches and twigs) apparently in approximately equal proportions but only rarely in flight; in another study, 41% of prey taken from twigs and stems, and 32% while perched, 49% in flight and 19% on ground. Sometimes hangs upside-down in manner of a tit (Paridae) while foraging, and also hawks flying insects in air in manner of a flycatcher (Muscicapidae). Lives and forages in tightly knit groups of 2–22 (average seven) individuals in undefended home range, which may be shared with adjacent groups, home-range size tending to increase during post-breeding period; groups smallest during breeding season, at least in S of range. Progresses in "leap-frogging" movement through woodland, birds at rear of group regularly flying to front; may trace identical foraging path day after day, and some individuals act as sentries while others forage. Especially in non-breeding season, joins mixed-species bird parties with P. retzii, towards which sometimes markedly aggressive, and, far less frequently, P. scopifrons, P. caniceps and P. poliolophus, as well as other birds, e.g. Old World orioles (Oriolidae), drongos (Dicrurus), tits and Brubrus (Nilaus afer), and likely catalytic in formation of these parties.

Noisy, vocalizations important in regulating intra-group social interactions; at least some calls may reflect individual social status. Wide variety of calls (at least 20 documented), many of which striking and protracted, including buzzing, chanting, chattering (on locating food or nest material), chipping, churring, clicking, gobbling, growling (during aggression), rolling, scolding, slurred, twittering, whistling, winding and, especially, nasal notes. Loud bill-snapping also characteristic, especially when provoked. Many calls given in group chorus and duets, including during territorial display, often initiated by dominant female. Breeding male and female maintain pair-bond through duetting, male giving "yuki-yuki" call, female responding with "kidoki-doki". Main call distinctive "cherow-cherow"; soft flight contact call "whit-whit", and louder "treeu" by lost individuals; alarm call shrill "tzzee-tzzee". Vocalizations apparently vary among subspecies, e.g. in E Africa reportedly between poliocephalus and cristatus.

Egg-laying virtually throughout year, especially Mar–Nov (mainly Mar–Jul and Oct–Nov), in W Africa, mainly Feb–Jun in NE Africa, Feb–Nov (mainly Feb–Mar and Oct–Nov) in E Africa, and mainly Aug–Apr (peak Sept–Nov) in C & S of range; often double-brooded, and in Zimbabwe, average of two (annual range 1·5–2·6) nesting attempts per season. Monogamous, pair-bond can last 2–3 years. Co-operative breeder, all group-members assisting in all aspects of nesting duties, breeding pair apparently doing most, intra-group hierarchy (in descending order of dominance) breeding female, breeding male, other adult females (typically siblings of breeding female), other adult males (typically siblings of breeding male), adult offspring, immatures and juveniles; breeding group stable for up to ten years, dominant breeding bird replaced on demise by next-ranking sibling of same sex; new group created when up to four sisters from one group join with up to four brothers of another group; some pairs without helpers, these are normally unsuccessful. Nest solitary, inter-nest distance typically at least 50 m, usually much greater; territorial during breeding, all group-members participate in territory defence, 63 territories in Zimbabwe 1–12 ha, average 5 ha. Courtship marked by wing-opening and slow wing-flapping, and male with nesting material in bill approaching female. Breeding pair chooses nest-site and does most of construction work, but assisted by other group-members, nest-building taking at least four days; nest a neat, compact cup of bark strips extravagantly bound with Microstigma spider web (web apparently transported in bill and on erectile frontal crest feathers), lined with bark, rootlets, grass and lichen, camouflaged to resemble swelling on branch, external diameter 8·1–9 cm, depth 3·5–6·5 cm, internal diameter 6·3–7·1 cm, depth 2·4–2·8 cm; placed 2–10 m (mainly 3–6 m) above ground on horizontal tree branch or in upright fork, often in tree with greyish or lichen-covered bark, sometimes in eucalypt plantation; has nested less than 80 m from P. retzii; same tree, even same site, may be used in successive years. Clutch 2–5 eggs, average 3·9 in Zimbabwe, occasionally two females lay in same nest (then up to 9 eggs in nest), eggs laid at daily intervals; replacement laid if clutch lost, in Zimbabwe average 11 days between nesting failure and new attempt; incubation by all group-members, breeding pair doing only c. 35% of it during daytime, incubation period 16–21 days, typically 17 days; chicks brooded and fed by all of group, nestling period 17–22 days, generally c. 20 days; fledged young fed by group-members until c. 10 weeks old, when able to locate food for themselves; from c. 5 months juveniles disperse from groups and form single-sex flocks with others, or remain in natal group as helpers. Three records of brood parasitism, one each by Thick-billed (Pachycoccyx audeberti), Red-chested (Cuculus solitarius) and Black Cuckoos (Cuculus clamosus); high rate of nest attendance may reduce opportunities for brood parasitism. In Zimbabwe, average of 25% of eggs and 30% of nests produce fledglings, 0·9 fledglings per nesting attempt, 2·9 fledglings per successful nest, and mean productivity 1·7 fledglings per group per year; average of 60% of fledglings survive first year; main cause of failure is predation by mammals, reptiles, and other birds e.g. Bateleur (Terathopius ecaudatus), Ayres's Hawk-eagle (Hieraaetus ayresii), African Harrier-hawk (Polyboroides typus), Gabar Goshawk (Micronisus gabar) and Peregrine Falcon (Falco peregrinus); some chicks starve to death. Can breed at two years, but fewer than 50% breed before five years old. In Zimbabwe, annual survival of adults 76–87%.

Not globally threatened. Frequent to common over large parts of range. Density of up to 1 group/10 ha in far S of range. In Zimbabwe, 140 home ranges 4·5–30 ha, average 18 ha, size associated with variables such as rainfall and density of adjacent groups; one non-breeding home range in South Africa 3·5 km². Occurs in numerous national parks and other protected areas throughout its range. May have benefited from drought refuges provided by plantations and urban parks and gardens.