In Costa Rica, there are three species of Oropendola, which as can be assumed are pretty similar. The biggest one is the Montezuma Oropendola, which is differentiated from the other too by black eyes, distal half of the beak is orange, and white skin on it’s face. The Crested Oropendola is very similar to the Chestnut-headed, however is bigger and has black head instead of chestnut. Both have pale bill and blue eyes, and all three species have yellow feathers on their tail. Another distinguishing characteristics is their range: The Crested has a very limited range near the border with Panama, while the other two can be found in the Caribbean (with the Montezuma being the most abundant). The Chestnut-headed can be found on the southern pacific, while the Montezuma can be found in Central Valley and northern pacific.
The following pictures were taken at Laguna del Lagarto Lodge, Boca Tapada during a Birdwatching tour with Fundación Rapaces de Costa Rica, on November 25th and 26th, 2017. It is more common to see the Montezuma come to the feeders, but this individual did come at least twice.