Anhimidae – Screamers

The Anhimidae or Screamers are a small clade of birds. For a long time, they were thought to be most closely related to the Galliformes because of similar bills, but DNA analysis reveals that they are instead more closely related to ducks (family Anatidae), most closely to the magpie goose (which some DNA evidence suggests are closer to screamers than to ducks). The clade is exceptional within living birds in lacking uncinate processes of ribs. The screamers are represented by three species.

They only occur in South America. They are large, bulky birds, with a small downy head, long legs and large feet which are only partly webbed. They have large spurs on their wings which are used in fights over mates and territorial disputes and can break off in the breast of other screamers. The spurs re-grow and are, anyway, regularly renewed. Unlike ducks they have only a partial moult, and are able to fly throughout the year. They live in open areas and marshes with some grass and feed on water plants. One species, the southern screamer, is considered a pest as it raids crops and competes with farmed birds.

They lay between 2 and 7 white eggs, with four or five being typical. The young, like those of most Anseriformes, can run as soon as they are hatched. The chicks are usually raised in or near water as they can swim better than they can run, which helps them to avoid predators. Like ducks, screamer chicks imprint early in life. This, coupled with their unfussy diet makes them amenable to domestication. They make excellent watchdogs due to their loud screams when encountering anything new and potentially threatening.

Both the southern and the horned screamer remain widespread and are overall fairly common. In contrast, the northern screamer is relatively rare and consequently considered near threatened. They are seldom hunted, in spite of their conspicuous nature, because their flesh has a spongy texture and is riddled with air-sacs, making it highly unpalatable. The main threats are habitat destruction and increased intensification of agriculture.