Identification

47–53 cm (male), 34.5–38 cm (female). All Olive Oropendolas, regardless of subspecies, have a distinctive, bare, pink or red cheek patch, and a large black bill tipped in red or orange. Subspecies yuracares and neivae are olive green on the head and breast, with reddish-brown wings and underparts, and a bright yellow-and-chestnut tail. The nominate subspecies has a blackish head, neck, and chest with chestnut wings, back, and underparts, and a yellow-and-chestnut tail.

While certainly a bird of mature rainforest, its large size and audible wingbeats can call attention to it in flight over a variety of habitats. As with other oropendolas, it nests colonially, building large pendulous nests in the crowns of tall trees.

Often presented as a relatively straightforward identification, there can be considerable confusion with other oropendolas that overlap in range; primarily Russet-backed Oropendola (Psarocolius angustifrons) and to a lesser extent, Green Oropendola (Psarocolius viridis). Variability between subspecies of this and other species complicates the situation. In all cases, bill and facial coloration are the most reliable field marks; with the Olive Oropendola reliably distinguished from other sympatric oropendolas by its dark bill tipped with red or orange and its large pink facial patch. The Olive Oropendola's large size and bicolored plumage (with chestnut wings in all subspecies) are also good distinguishing features; however, both can be subjective under field conditions. Note that green-plumaged oropendolas can appear all dark in certain lighting conditions.

The Olive Oropendola is the largest of the South American oropendolas, and can be reliably distinguished from other similar species by a combination of features including its dark bill tipped with red or orange, its large pink facial patch, and its bicolored plumage (subspecies yuracares and neivae have mustard greenish heads, necks, and chests and chestnut wings and underparts; subspecies bifasciatus has a black head, neck, and breast with chestnut wings and underparts).

The Russet-backed Oropendola (Psarocolius angustifrons) can be differentiated by its nearly uniform dingy olive or russet coloration, unlike the distinctive bicolored plumage of Olive Oropendola (1 Cassin, J. (1867). A third study of the Icteridae. 3. Sub-family Icterinae. Proceedings of the National Acadamy of Science of Philadelphia 19:45–74. Close , 2 Jaramillo, A., and P. Burke (1999). New World Blackbirds: The Icterids. Christopher Helm, London, UK. Close , 3 Hilty, S. L. (2003). Birds of Venezuela. Princeton University Press, Princeton, NJ, USA. Close , 4 Ridgely, R .S., and G. Tudor (2009). Field Guide to the Songbirds of South America: the Passerines. University of Texas Press, Austin, TX, USA. Close ). As with other sympatric oropendolas, bill color is also a good indicator; the bill is entirely light or dark in Russet-backed Oropendola, and lacking the pink facial patch. Olive Oropendola is more likely to be found in mature upland forest than Russet-backed Oropendola, which prefers more open habitats.

The Green Oropendola (Psarocolius viridis) is the most widely sympatric green-plumaged oropendola. It has olive (not chestnut) wings, a pale green-and-red bill (though also tipped with orange), and it lacks the conspicuous pink cheek patch. Dusky-green Oropendola (Psarocolius atrovirens) is similar but smaller than the Russet-backed Oropendola, with a darker olive head.

Crested Oropendola (Psarocolius decumanus) is also sympatric, but can be separated by a combination of its smaller size, dark color, pale blue iris, and pale bill. The nests of subspecies yuracares in Bolivia were noted to be easily distinguished from the nests of sympatric Crested Oropendola (5 Fraga, R.M. and Kreft, S. (2007). Natural history and breeding behavior of the Olive (Psarocolius yuracares) and Yellow-billed (P. angustifrons alfredi) Oropendolas in the Chapare province, Bolivia. Orn. Neotropical 18(2): 251–261. Close ), in that the Crested Oropendola's nests were neatly woven and elongate pyriform in shape, in contrast to the the nests of Olive Oropendola, which were more noticeably more cylindrical, built of coarser fibers, and tended to be more thickly clustered (each nest less isolated within the colony).