Russet-backed Oropendola (Psarocolius angustifrons) [XC471416]
by Mauricio Cuellar Ramirez (@Birding.travel) from Avispas, cerca de Villa Tunari, Chapare, Departamento de Cochabamba, Bolivia (song)
Russet-backed Oropendola (Psarocolius angustifrons) [XC259996]
by John V. Moore from Napo: 'Caba\u00f1as San Isidro', 1-2 km SW Cosanga, Ecuador (call, song, calls)
Subspecies
Taxonomy complex and confusing. Recent fieldwork in foothills of Colombian eastern Andes revealed that subspecies neglectus does not associate with nominate, the two behaving as separate species, and this supported by DNA studies indicating considerable sequence divergence between the four northern Andean forms (Venezuela south to Ecuador) and nominate subspecies. Also, songs of some of northern Andean subspecies are distinctive. On other hand, DNA divergence between alfredi and nominate was relatively small, and songs of the two are similar, suggesting that they are conspecific (also, intermediate specimens reported from eastern Ecuador). Analyses of mitochondrial DNA indicate considerable divergence between some montane populations, which may deserve full species status, but a more detailed analysis of the full complex is needed.
Proposed subspecies australis (described from Santa Cruz, in central Bolivia) supposedly darker than alfredi, but considered to fall within range of variation of latter and therefore synonymized with it.
The following 7 subspecies are recognised:
oleagineus (Sclater, PL, 1883) - Mountains and foothills of coastal northern Venezuela (from Carabobo east to Miranda). Considered by some authors to be a distinct species, Green-billed Oropendola (Psarocolius oleagineus).
neglectus (Chapman, 1914) - Sierra de Perijá (Colombia-Venezuela border); western Andes of Venezuela and eastern slope of eastern cordillera in Colombia (south to Caquetá).
salmoni (Sclater, PL, 1883) - Western and central Andes of Colombia (south to Nariño).
sincipitalis (Cabanis, 1873) - Western slope of eastern Andes of Colombia (from Santander south to upper Magdalena Valley).
atrocastaneus (Cabanis, 1873) - Western slope in Ecuador.
alfredi (Des Murs, 1856) - Eastern Andean slopes and foothills from south-eastern Ecuador (Morona Santiago) south to Peru and central Bolivia (Cochabamba and Santa Cruz).
angustifrons (Spix, 1824) - Low eastern Andean foothills from southern Colombia (southern from Meta and Vaupés) south to eastern Ecuador and north-eastern Peru (Loreto and northern Ucayali) and western Brazil (Amazonian lowlands east to lower R Purús).
BirdLife International Species Factsheet