Oropendolas are medium sized weaver birds. They build extravagant nests that hang 3-6 feet from tree branches to keep their young safe from predators such as snakes. These birds are very social and live in flocks numbering up to 100 birds.  The Crested Oropendola has a characteristically large beak and black feathers all over with the exception of bright yellow tail feathers. Male birds are brighter than their female counterpart.