White-gaped Honeyeater Stomiopera unicolor Scientific name definitions

Male 19–22 cm, 27·8–40·4g; female 17–20 cm, 25–33 g. Plumage is plain dark olive-brown to greyish-olive above, and slightly paler and greyer below, slightly paler on vent and with faint pale yellow tinge on centre of belly; diffuse dusky lores, white to cream gape bulging upwards in semi-circular patch; tail feathers and secondaries have faint greenish wash on outer edges, primaries have fine off-white outer edges; undertail olive-grey, under­wing greyish-white and merging into dusky on trailing edge and tip; iris brown or grey-brown, sometimes olive-grey or blue-grey; bill black; legs dark grey to black, soles paler. Sexes alike in plumage, male slightly larger than female. Juvenile is very similar to adult and some probably inseparable in field, but initially distinguished by combination of softer plumage of upperbody, faint brown tinge on hindneck, upper mantle and rump, slightly stronger yellow wash on centre of belly, and (at least sometimes) brighter yellow gape.

N Australia from Melville I and N Western Australia (Kimberley Division and offshore islands) E throughout Top End of Northern Territory (S to upper Victoria R in SW and to Barkly Tableland in SE), and on Groote Eylandt, to N Queensland (S to near Proserpine; occasional records farther S, e.g. Mackay, and on Atherton Tableland).

Mainly riparian forests and woodlands, frequently riverine or swamp associations dominated by paperbarks, e.g. weeping paperbark (Melaleuca leucadendra), or, less often, Lophostemon, or mixed assemblages of Melaleuca, Lophostemon, Eucalyptus, casuarina or Erythrina, and usually with dense thickets of screw-palms (Pandanus) and Acacia in understorey, or in mixed stands of Eucalyptus and Pandanus. Commonly also in monsoon rainforests. Ranges into open eucalypt woodland or savanna adjoining riverine forest, usually with grassy understorey and scattered shrubs or shrubby understorey; and occurs in ecotone between monsoon forest and open forest of acacias and eucalypts. Sometimes in mangroves, in Acacia forest or scrub, in spinifex (Triodia) grassland with scattered shrubs on sandstone plateaux, and in wet mosaic grassland and sedgeland. Also in gardens and parks in towns and around human habitation.

Resident. No evidence of nomadism, but possibly moves locally to exploit flowering; at Victoria River Downs, local range contracts during dry season. Occasional visitor or vagrant to sites at edge of range; unconfirmed early report from NE New South Wales.

Diet includes nectar, fruit, seeds and invertebrates (mainly insects, also spiders). Usually forages in dense vegetation, from canopy to near ground; mostly on bark of trunks and branches of trees, shrubs and palms, or among green or dead foliage, but also on fruit and at flowers of trees and shrubs, and in air. Selects flowers that provide best source of nectar, which obtained by probing. Arthropods mainly gleaned from foliage (including palm fronds) and bark; captures aerial insects by sallying, less often performs sally-hovering to take prey from foliage, or flutter-chasing. Inspects spider webs; searches around buildings and even enters them. Seen to eat arils attaching seeds to seedpods of black wattle (Acacia auriculiformis). Usually singly, in twos (probably pairs) or threes, or in small groups of up to 6–8 individuals; sometimes feeds with other honeyeaters, or with other bird species.

Song loud and ringing or fluting, three similar phrases separated by interval of c. 0·5 seconds, e.g. “whit-o-wee” or “whit whit, awhit-whit, awhit-whit”; usually as duet whenever pair-members meet and to advertise territory, male initiating duet and female joining in after a pause (second and third phrases completely synchronized); can start song before alighting from flight, and male may respond instantly with loud song to unusual sounds, to entry of rival into territory, or to approach of potential predator. Apparent contact call, given frequently, “chiew” or “chop”, uttered at intervals of many seconds to minutes, also as nearly monosyllabic clicking “tyiet”; other calls include short, harsh repeated “chirrup” or “chirp” or rapid “chp-chp-chp-chp-chp-chwerp”, seldom heard and thought to be a contact call, also a soft warble by brooding bird on approach of mate, also loud chattering. Snaps bill during agonistic interactions.

Probably throughout year, and recorded in all months except Jun near Darwin (Northern Territory); clutches Jul–Mar. Nest built by female, accompanied by male, a deep cup, usually made of bark or grass, bound with spider web or spider egg sacs, sometimes includes rootlets, grass, hair, plant fibres, twigs or casuarina needles, unlined or sparingly lined with fine grass or with plant down, nest said by some authors to be covered with shining layer of saliva (which helps to bind materials and make nest solid), external diameter 8–12·1 cm, depth 7–8·9 cm, internal diameter 5·4–8 cm, depth 3·8–6·4 cm; usually suspended from twig fork in topmost branches of live leafy tree or shrub, including mangrove and in mistletoe (Loranthaceae), occasionally near centre of tree, usually near water; six nests were 1·5–3·3 m (mean 2·18 m) above ground, but others reported as low as 1·2 m and as high as 12 m. Clutch usually 2 eggs; incubation by female, from second egg, period 15–16 days; chicks brooded by female, or allegedly by both parents, fed by both parents (possibly by female only for first 2 days), nestling period at one nest 13–14 days; both adults feed fledglings.

Not globally threatened. No estimates of total population; recorded densities of up to 2 birds/ha. Formerly considered common at Mt Isa, in NW Queensland, but now recorded only N of there; formerly considered common or recorded at Ayr and Mission Beach, but no recent records. In study of effects of long-term exclusion of fire in Northern Territory forests, this species was found to be significantly more abundant in unburnt quadrats.