Averla formichiera barrata

Identificazione

The barred antshrike is 15 to 18.5 cm (5.9 to 7.3 in) long and weighs 24 to 32 g (0.85 to 1.1 oz). Members of genus Thamnophilus are largish members of the antbird family; all have stout bills with a hook like those of true shrikes. This species exhibits marked sexual dimorphism though both sexes have a bushy crest. Adult males of the nominate subspecies T. d. doliatus are almost entirely plumaged with alternating black and white bars. The black bars on their upperparts are thicker than the white bars; on their underparts the black bars are thinner than the white ones. Their face, throat, and chin have thin black and white streaks. Their crest is black with white bases on the middle feathers. Adult females have a cinnamon-rufous crest and upperparts. The sides of their head and neck are streaked black and white or buff. Their chin is buff and their underparts ochraceous-buff. Adults of both sexes have a pale yellow iris, a black maxilla, a bluish gray mandible, and lead-gray legs and feet. Juvenile males are barred with black and light yellowish brown.<p>The other subspecies of the barred antshrike differ from the nominate and each other thus:

Tassonomia

The barred antshrike was described by the Swedish naturalist Carl Linnaeus in 1764 and given the binomial name Lanius doliatus. The type locality was subsequently designated as Surinam. The specific epithet is from Neo-Latin doliatus meaning "barred". <p>The barred antshrike has these 12 subspecies:<p>Subspecies T. d. capistratus was proposed as a separate species but the data presented confirmed its treatment as a subspecies of the barred antshrike.<p>What is now Chapman's antshrike (T. azrumae) was for a time treated as a subspecies of the barred antshrike.

Nome scientifico

Thamnophilus doliatus

Autorità

(Linnaeus, 1764)

Ordine

Passeriformi

Famiglia

Thamnophilidae

Genere

Thamnophilus

Areale e habitat

The subspecies of the barred antshrike are found thus:<p>The barred antshrike inhabits a variety of landscapes with some geographical differences. In all areas it favors thick undergrowth rather than higher parts of the habitat and shuns the interior of mature forest. In Mexico, Central America, northern South America, and much of Peru it inhabits scrublands (especially second-growth), riparian thickets, the edges of dry woodlands and secondary forest, and even gardens. The exceptions are T. d. eremnus, which inhabits tropical deciduous forest on Coiba Island, T. d. tobagensis, which inhabits mature humid forest on Tobago, and T. d. capistratus, which primarily inhabits caatinga and restinga in eastern Brazil. In eastern Colombia the species often occurs on river islands, and in Ecuador, northern Peru, and much of Brazilian Amazonia it occurs almost exclusively on them. In Brazil it also is found on the "mainland" along rivers. In southern Bolivia, Paraguay, and Argentina it adds savanna to the scrub, secondary forest, and riverine belts. In Mexico, Central America, and Colombia it is found from sea level or near it to 1,500 m (4,900 ft). In Venezuela it reaches 2,000 m (6,600 ft) though most records are below 1,250 m (4,100 ft); in Peru it reaches 1,400 m (4,600 ft). In Ecuador it is found only below 250 m (800 ft).

Migrazione

Resident species

Comportamento

The barred antshrike is a year-round resident throughout its range.<p>The barred antshrike has a cosmopolitan diet. It primarily feeds on a wide variety of mature and larval insects but also includes significant amounts of other arthropods, small lizards, fruit, and seeds. It typically forages in pairs that remain close together in dense foliage from the ground to about 3 m (10 ft) above it, but will go as high as 10 m (35 ft). It almost never joins mixed-species feeding flocks. It hops and makes wing-assisted jumps up from the ground and between branches, and also climbs branches and vines. It usually gleans prey from leaves, stems, branches, and trunks using a rapid stabbing motion. It also feeds on prey that flees army ant swarms.<p>The barred antshrike is monagamous and pairs vigorously defend year-round territories. In one study the territories were about 2,500 to 4,200 m2 (0.62 to 1.0 acre). The species' breeding season varies considerably across its large range, and every month of the year is represented somewhere. In Trinidad and Tobago it apparently breeds at any time of year. The species' nest is a tightly woven, though thin-walled, open cup made of fungal and vegetable fibers, vines, grasses, and twigs. It is usually suspended by its rim from a branch fork up to 10 m (35 ft) above the ground, though the heights appear to vary geographically. Both sexes build the nest. Their usual clutch size is two eggs, though three have been reported on Trinidad. Both parents incubate during the day but only the female at night. In a Costa Rican study the eggs were laid a day apart and the incubation period was 13 days after the second egg. In studies in other countries the time from hatch to fledging was 10 to 13 days. Both parents brood and provision nestlings.<p>Both sexes of the barred antshrike sing; while singing they stretch their neck, bow forward, and pump their tails up and down. Males erect their crest, which shows the feathers' white bases in the subspecies that have them. The species' song or songs have not been extensively studied across its range, but the general pattern is "a long series of loud chuckling or cackling notes that rapidly ascend with increasing intensity, and then descend, ending with an emphatic final note". Fagan and Komar, writing about the birds of northern Central America, describe it as "wha-wha-Wha-WHA-WHA-WHA-WHA'WHA'WHA'WHA'WHA'WHA-WRAY!". Schulenberg et al. for Peru write it as "kyuh kya-kya-kya-kya'ko'kokoWAH!". Ridgely and Greenfield for Ecuador write it as "hah-ha-ha-hahahahahahahaha-hánh".<p>The barred antshrike's calls vary among the subspecies, though a "crow-like caw" seems to be nearly universal though its function is not known. Some other calls include "growling or guttaral calls [and] a short nasal 'nah!' ", "a nasal, strained cuee, ueee, ueee [and] a low growl, graaaaa", and "a nasal AW and a mewing whistled wheeu".

Conservazione

Tendenza della popolazione

stable