South American Leaftosser

Identificazione

The dusky leaftosser is 15 to 17 cm (5.9 to 6.7 in) long and weighs 20 to 30 g (0.71 to 1.1 oz). The sexes are alike. Adults of the nominate subspecies S. o. obscurior have dark reddish to chestnut brown upperparts, with their rump and uppertail coverts being more chestnut than the reddish back. Their wings are darker brown than their back and their tail is dark brown to black brown. Their face is brownish, their throat is tawny chestnut, and their chest and breast are a darker chestnut. Their bill is fairly long and straight with a dark maxilla and a bicolored mandible. Their iris is brown and their legs and feet are dusky to black. Juveniles are similar to adults but are overall duller and have light streaks on their breast and a light scaly appearance on their throat and chest.<p>Subspecies S. o. andinus is generally paler than the nominate but has a brighter rufous cast to its rump. S. o. peruvianus has entirely dark reddish brown upperparts without the chestnut rump of the nominate and andinus. S. o. macconnelli is similar to peruvianus but is somewhat olivaceous overall with a more tawny throat. S. o. bahiae has a browner back, a much brighter chestnut rump, and a darker throat than the other subspecies.

Tassonomia

The dusky leaftosser's taxonomy is unsettled. The South American Classification Committee of the American Ornithological Society (AOS), the International Ornithological Committee (IOC), and the Clements taxonomy assign it these five subspecies:<p>The North American Classification Committee of the AOS and BirdLife International's Handbook of the Birds of the World (HBW) retain an older treatment. They place these subspecies within S. mexicanus, which they respectively call the Middle American leaftosser and the tawny-throated leaftosser.<p>This article treats the dusky leaftosser as a species with five subspecies.

Nome scientifico

Sclerurus obscurior

Autorità

Hartert, EJO, 1901

Ordine

Passeriformi

Famiglia

Furnariidae

Genere

Sclerurus

Areale e habitat

The distribution of the subspecies of the dusky leaftosser are in dispute. According to the IOC and Clements, they are found thus:<p>According to other sources detailed in Cooper et al, they are distributed thus:<p>With the exception of disjunct S. o. bahiae, the exact spatial and elevational boundaries between the subspecies are not known.<p>The dusky leaftosser generally inhabits moist tropical evergreen forest throughout its range, from lowland rainforest to humid sub-montane forest. In elevation the various subspecies range from near sea level to about 1,100 m (3,600 ft) in Brazil, 1,500 m (4,900 ft) in Ecuador, 2,100 m (6,900 ft) in Colombia, and 2,000 m (6,600 ft) in much the rest of the Andes.

Comportamento

Il voltafoglie scuro è stanziale tutto l'anno nell'intero areale.<p>Cerca il cibo soprattutto a terra, spostando le foglie e becchettando nella lettiera e nei tronchi marcescenti; si muove saltellando anziché camminando. Solitamente si alimenta da solo o in coppia. La dieta è composta soprattutto da invertebrati e, pur non essendo stata descritta in dettaglio, comprende ragni, coleotteri, formiche, blatte e le loro larve.<p>Si ritiene che sia monogamo. La stagione riproduttiva non è stata definita per l'intero areale, ma comprende aprile e maggio in Colombia e aprile nella Guyana francese. Nidifica in un cunicolo nel terreno, con una coppa poco compatta di rametti secchi nella camera terminale. La covata comprende due uova.<p>Il canto varia leggermente tra le sottospecie per altezza e numero di note, ma è generalmente «una serie melodiosa discendente di 4–15 fischi, ciascuno con andamento ascendente». Può iniziare con «un netto spik!» e terminare con «alcune brevi note balbettanti». Il richiamo principale è «una singola nota breve, acuta ed esplosiva, Tseek!», solitamente emessa a intervalli irregolari; quando l'uccello è eccitato, forma invece una lunga sequenza.