Russet-backed Oropendola Psarocolius angustifrons

A medium-sized oropendola; fairly common in lowlands but seems to be scarce in montane forest. Can occur up to around 2,500m in the Andes, where it is usually the only oropendola and unlikely to be confused. Generally olive overall with warmer rufous tones on back and rump. Variable bill color: dark blackish in the Amazonian lowlands; usually yellowish in Andes. Yellow outer tail feathers like other oropendolas. Typically in flocks that forage in the canopy, sometimes in mixed flocks with other oropendolas or caciques.