Olivaceous Woodcreeper

Identificazione

The olivaceous woodcreeper is one of the smallest members of its subfamily. It has a slim body and a short straight bill, and unlike most other woodcreepers has no streaks or spots. The sexes' plumages are alike but females average smaller than males. Adults are 13.1 to 19.3 cm (5.2 to 7.6 in) long. Males weigh 9.0 to 18.0 g (0.32 to 0.63 oz) and females 8.6 to 16.0 g (0.30 to 0.56 oz). Length and weight vary geographically. All subspecies have a dark iris, a dark gray to black maxilla, a black to light gray mandible with a darker tip, and gray, bluish gray, or black legs and feet.<p>The nominate subspecies S. g. griseicapillus is mostly olivaceous, with an olive-brown hindcrown and rufous rump, tail, and flight feathers. Its vent area is grayish and its flanks buff. In flight the wing shows a tawny band. The other members of the "Amazonian" subspecies group are similar but differ from it thus:<p>The six subspecies of the "grayish" group are mostly olive but with a contrasting brown back. Their wings and tail are rufous. The subspecies vary somewhat with the olive parts tending in some to gray, the brown back in some being somewhat reddish or a deeper brown, and the wing band varying among whitish, buff, or tawny.<p>The two subspecies of the "olivaceous" group are overall olive-yellow, with deep rufous tails and flight feathers. S. g. sylviellus tends to mustard yellow and S. g. olivaceus is more olive. The "Pacific" subspecies S. g. aequatorialis is similar to the "grayish" group but has a browner back and pale tawny tail and flight feathers. "Reiser's" subspecies S. g. reiseri has a cinnamon-brown hindcrown, head, and mantle. Its tail and flight feathers are pale but rich rufous, its "wingpits" ochraceous, its flanks cinnamon, and its vent area cinnamon-buff.

Tassonomia

The olivaceous woodcreeper is the only member of genus Sittasomus. However, taxonomic systems vary in their treatment of the taxon, with some splitting it into two species. The International Ornithological Committee and the Clements taxonomy assign these 15 subspecies to the olivaceous woodcreeper; Clements distributes them among five groups.<p>"Grayish" group<p>"Pacific"<p>"Amazonian" group<p>"Reiser's"<p>"Olivaceous" group<p>BirdLife International's Handbook of the Birds of the World (HBW) splits the olivaceous woodcreeper into two species. It retains the eight "Amazonian", "Reiser's", and "Olivaceous" subspecies as S. griseicapillus but with the English name "eastern olivaceous woodcreeper". It places the seven "grayish" and "Pacific" subspecies in S. griseus with the English name "western olivaceous woodcreeper".<p>The North American and South American Classification Committees of the American Ornithological Society treat the olivaceous woodcreeper as one species but note that it probably consists of several species, perhaps as many as five corresponding to the Clements groups.<p>The olivaceous woodcreeper is genetically most closely related to the long-tailed woodcreeper (Deconychura longicauda).

Nome scientifico

Sittasomus griseicapillus

Autorità

(Vieillot, 1818)

Ordine

Passeriformi

Famiglia

Furnariidae

Genere

Sittasomus

Areale e habitat

The subspecies of the olivaceous woodcreeper are found thus:<p>The olivaceous woodcreeper inhabits a variety of wooded landscapes, generally favoring all parts of mature forest but also occurring in secondary forest and plantations. Mature landscapes include rainforest, semi-deciduous forest, terra firme and várzea forests, evergreen montane forest, cloudforest, and gallery forest. In drier areas it occurs in scrublands, caatinga, and cerrado. It has also been recorded in stands of bamboo, pine forest, mangroves, coffee plantations, and urban parks.<p>The olivaceous woodcreeper inhabits a range of elevations. In northern Central America it occurs from sea level to 1,950 m (6,400 ft). Subspecies S. g. axillaris is fairly common between 1,200 and 1,400 m (3,900 and 4,600 ft) and is found as low as 850 m (2,800 ft). In Colombia it occurs below 2,000 m (6,600 ft) and in Ecuador mostly below 1,100 m (3,600 ft) but as high as 2,000 m (6,600 ft). It reaches as high as 2,300 m (7,500 ft) in northern Venezuela, Bolivia, and southeastern Brazil.

Migrazione

Specie stanziale

Comportamento

Comportamento migratorio: Specie stanziale.

Conservazione

Tendenza della popolazione: in diminuzione.

Tendenza della popolazione

in diminuzione