Weebill is the shortest bird in Australia. The bird belongs to the family Acanthizidae. Often found in eucalypt woodlands and open forests, the Weebill (Smicrornis brevirostris) feeds on the outer foliage one to 20 meters above the ground.
It is generally regarded as undesirable to have dense forests or woodlands that contain other trees besides eucalypts. Birds of this species are social and vocal, gleaning among leaves in pairs or loose groups of 10 to 20, searching for small insects and larvae.
Most often, they flit about, hopping and clinging to foliage, often well above the ground in the canopy, but they sometimes hover over leafy branches, wingbeats pounding rapidly, to capture flying insects. Eucalypt woodlands are often dominated by this song at midday, which is often repeated several times with little variation.
Weebills feed in eucalypt trees, usually in company with other small birds such as thorn bills and pardalotes, as they move from tree to tree. At all times of the day, feeding parties keep in touch by buzzing with sharp notes, and individuals will sing sporadically as well. Sedentary birds with established foraging ranges and groups of Weebills stay in one place permanently. It feeds mostly on insects, larvae, and occasionally seeds. Spiders, beetles, and flies are among the arthropod prey items.
It is common for males to attend to females and sing about the nest site during breeding, but do not contribute much to nest construction. At the nest site, the birds display tail-fanning and slight bowing and wing-quivering to each other. A female’s incubation period lasts about 12 days. When young fledge around 10 days after hatching, several birds from the local group feed them in addition to their parents. Each year, there are two to four broods.
In Australia, weebills are found nowhere else-and their plumage colors differ based on where they are found. In southern Australia, they have mid-olive-green backs, gray heads, creamy underparts, and a dusky throat spotting. In central Australia, they retain the contrast between upper and underparts but become paler.
There are no throat marks in the northern part of the state, and they are suffused with yellow. Races blend into one another so imperceptibly that it is impossible to distinguish them. Its flocking and contact calls resemble those of thorn bills, but its songs, feeding, and tail markings resemble those of gery-gones. Its eggs resemble those of scrub wrens.
Weebills are also known as Brown Weebills, Yellow Weebills, Yellow Tree-tits, Short-billed Scrub-tits, Short-billed Tree-tits, and Southern Weebills. John Gould first described it in 1838, and four subspecies have been identified.
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S. b. flavescens
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S. b. ochrogaster
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S. b. occidentalis
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S. b. brevirostris
Weebills ruffle their cheeks and head feathers with outstretched wings in courtship displays. At the nest site, male and female weebills display tail-fanning, slight bowing, and wings quivering to each other.
Weebills measure about 80-90 mm in length. There is no difference between the sexes of adults. The head is grayish and the upper parts are dull olive-brown with olive-yellow highlights, especially on the lower back and rump. In some forms, an off-white stripe extends from the forehead over the eye and a rufous-brown spot appears in front of it.
On all but one or two pairs of the tail feathers, the inner webs of the tail are ash-brown with a broad black bar and a distinct white spot.
The wings are brown; the flight feathers are ash-olive with olive-yellow edges. The chin and throat are dull to yellow-white, sparsely striped with black in some forms, merging into the plain yellow buff and rich light yellow on the breast and belly; the color is deepest on the belly and flanks.
The eyes are straw to pale cream-yellow in color. The lower mandible is paler than the upper mandible, the bill is pale gray to flesh-brown. The feet and claws are pale greys to flesh-brown in color. A mature adult’s eyes are greyer than an immature adult’s.
A weebill’s call is harsh, sharp, buzzing in contact, mostly in flight; repeated frequently. Throughout the year, weebills sing a lively, surprisingly strong song of usually four whistled slurs, the last two higher and drawn out, repeated rapidly several times with little variation, weebill, wee bill, weebee, or weet, weetee.
During the breeding and nesting season in the south, it is August-February; in the north, it is October-April-May. It all depends on the rains, but it probably coincides with the population of the south.
In dense foliage of the tree canopy, nest neat, round to pear-shaped domes made from fine pliable materials. Nest with a narrow spout-like entrance near cop; of wiry grass and plane, it is tightly bound together with cobwebs, insect cocoons, animal hair to bind, and spider egg sacs; lined with feathers and plant down; attached to slender, leafy branches at a distance of two to ten meters.
Weebills lay two or three eggs; cream-buff, finely speckled with buff-brown to purple-brown, particularly at the larger end. Eggs measure about 15 x 12 mm and are oval in shape. For females, the incubation period is about 2-13 days. In about 9-10 days, the young fledge. In mainland Australia, the species is widely distributed in eucalypt woodlands and open forests.
Throughout its range on mainland Australia, it is a common bird. The IUCN Red List of Threatened Species rates the weebill as Least Concern. A number of disturbances caused by humans can result in changes to ecosystem-level processes, modify habitat structure, and ultimately affect fauna assemblages. These disturbances include introduced flora and fauna species, and altered fire regimes. Read More – Grey Headed Robin
