Mirmotera grigia

Identificazione

The grey antwren is 8.5 to 10.5 cm (3.3 to 4.1 in) long and weighs 8 to 9 g (0.28 to 0.32 oz). It is a smallish bird with a short tail. Adult males of the nominate subspecies M. m. menetriesii are almost entirely bluish gray, with lighter underparts than upperparts. Their wing coverts have white tips and a black bar just above them. Their tail feathers have narrow white tips. The center of their throat and upper breast are black, sometimes with gray tips on the throat feathers. Adult females have olive-tinged gray upperparts with somewhat darker wings. Their throat is buff and the rest of their underparts rich olive-buff. Juveniles look like a darker version of the adult female. Subadult males have a buff tinge on the wings, gray and pale buff patches on the breast, buff-tinged olive sides and flanks, and a buff crissum.<p>Males of subspecies M. m. berlepschi are similar to the nominate but less bluish, and with a blackish band near the end of the tail. Females' upperparts are more cinnamon-rufous and their underparts a richer tawny-ochraceous than the nominate's; they have cinnamon edges on the flight feathers. Males of M. m. cinereiventris have a gray throat and breast with at most a few black spots on the latter. Females have brownish olive upperparts. Males of M. m. omissa are like cinereiventris males; females have yellow-ochre underparts. Males of M. m. pallida are a paler version of cinereiventris and omissa but with a whitish crissum. Females are similar to the nominate.

Tassonomia

The grey-throated antwren has these five subspecies:

Nome scientifico

Myrmotherula menetriesii

Autorità

(d'Orbigny, 1837)

Ordine

Passeriformi

Famiglia

Thamnophilidae

Genere

Myrmotherula

Areale e habitat

The subspecies of the grey antwren are found thus:<p>The grey antwren inhabits the mid-storey to subcanopy of terra firme and transitional lowland evergreen forest. In Brazil it ranges from near sea level to 1,000 m (3,300 ft) and reaches that elevation locally elsewhere. In Colombia it occurs mostly below 500 m (1,600 ft) and in Ecuador mostly below 600 m (2,000 ft).

Migrazione

Resident species

Comportamento

The grey antwren is believed to be a year-round resident throughout its range.<p>The grey antwren's diet is mostly insects and spiders. It forages singly, in pairs, or in family groups, and almost always as part of a mixed-species feeding flock. It feeds mostly between about 6 and 20 m (20 and 70 ft) above the ground though sometimes as low as 3 m (10 ft) and as high as 25 m (80 ft). It very actively, almost frenetically, seeks prey mostly on live leaves and also from vines, stems, and branches, by reaching, hanging, lunging, and occasionally by fluttering up from a perch.<p>The grey antwren's breeding season is not known but appears to vary geographically. Observations show that it includes February in Colombia and Venezuela, December in French Guiana, and July in Bolivia. Its nest is a bundle or ball of dead leaves in the fork of a branch. The clutch size, incubation period, time to fledging, and details of parental care are not known.<p>The grey antwren's song in Brazil is described as an "ascending series of 6-8 eerie, two-syllabled 'wueeih' notes". In Ecuador it is "a wavering series of 10-12 'ree' or 'shree' notes that rise in pitch and accellerate a bit". The species' calls are "multi-noted [and] include higher-pitched abrupt notes and lower, slightly longer ones in varying combinations"; all are delivered rapidly.

Conservazione

Tendenza della popolazione

declining