The sole representative of the genus Ocyalus, this small black and generally rare oropendola is a distinctive and unusual species. The nape is dark chestnut, with blue eyes, and a very distinctive tail pattern, appearing largely yellow with a broad black tip and narrow black edges, which is perhaps best appreciated when seen below, although if the tail is held tightly closed then it can appear virtually all black. The pale bill is rather broad with an obviously enlarged frontal shield. The Band-tailed Oropendola inhabits the upper stories of seasonally flooded and swamp forests, including on river islands, and is almost endemic to eastern Peru, although it ranges north to southernmost Colombia and further east into western Amazonian Brazil. Although the species has occasionally been found nesting in colonies of its own kind, the Band-tailed Oropendola appears to usually nest alone, albeit within colonies of other oropendolas, perhaps especially Casqued Oropendolas (Psarocolius oseryi).