17. Hoatzin
Hoatzin (Opisthocomus hoazin), endemic bird of the Amazon Region perched on the branch
Next on our list of ugly birds is the primitive-looking hoatzin (Opisthocomus hoazin). These are colorful birds with dark brownish upper parts, a blue face, and a loose, spiky head crest.
These ugly birds are the only living species of an ancient avian lineage, which gives them a special status.
However, there are several other characteristics that set it apart from other birds. For instance, baby hoatzins have two claws on each wing which helps them climb up on trees in case they fall down from the nest.
Additionally, these are the only birds that are able to ruminate – they digest their food through bacterial fermentation.