When we arrived at the oxbow lake, the first birds we saw were a group of Horned Screamers. The screamers are a group of south american birds related to the ducks. While we watched, they performed their namesake calls.
The Horned Screamer (Anhima cornuta) is a member of a small family of birds, the Anhimidae, which occurs in wetlands of tropical South America. There are three screamer species, the other two being the Southern Screamer and the Northern Screamer in the genus Chauna. They are related to the ducks, geese and swans, which are in the family Anatidae, but have bills looking more like those of game birds.