| Screamer | |
|---|---|
_-_the_weird_looking_Southern_Screamer_(Chauna_torquata)_-_(24213807344).jpg) | |
| Southern screamer (Chauna torquata) | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Anseriformes |
| Suborder: | Anhimae Wetmore & Miller 1926 |
| Family: | Anhimidae Stejneger, 1885 |
| Genera | |
Thescreamers are three South Americanbird species placed infamilyAnhimidae. They were thought to be related to theGalliformes because of similarbills, but are more closely related to the familyAnatidae, i.e.ducks and allies,[1][2] and themagpie goose,[3] within the cladeAnseriformes. The clade is exceptional within the living birds in lackinguncinate processes of ribs.[4] The three species are: Thehorned screamer (Anhima cornuta); thesouthern screamer or crested screamer (Chauna torquata); and thenorthern screamer or black-necked screamer (Chauna chavaria).
Anhimids are most similar topresbyornithids, with which they may form a clade to the exclusion of the rest of Anseriformes. Given the presence of lamelae in the otherwise fowl-like beaks of screamers, it is even possible that they evolved frompresbyornithid-grade birds, reverting from a filter-feeding lifestyle to an herbivorous one.[5]
Screamers have a poor fossil record.Anachronornis from theEocene ofWyoming was originally suggested to be a screamer but is now though to be a basalanseriform, while the more modernChaunoides antiquus is known from the lateOligocene to earlyMiocene inBrazil.Eoneornis from the Miocene of Argentina was originally described as an indeterminate anseriform but shows some similarities with Anhimidae, especiallyChaunoides.[6]
| Image | Genus | Living species |
|---|---|---|
 | Anhima |
|
 | Chauna |
|
The three species occur only inSouth America, ranging fromColombia to northernArgentina. The horned screamer was once present on theCaribbean island ofTrinidad, but is now extirpated from there. They are large, bulky birds, with a small downy head, long legs and large feet which are only partially webbed. They have largespurs on their wings which are used in fights over mates and territorial disputes;[2] these can break off in the breast of other screamers, and are regularly renewed. Unlike ducks, they have a partialmoult and are able to fly throughout the year.[2] They live in open areas and marshes with some grass and feed on water plants. One species, the southern screamer, is considered apest as it raids crops and competes with farm birds.
Screamers typically lay 4–5 white eggs, with clutches ranging between 2 and 7 . Like mostAnseriformes, the chicks can run as soon as they are hatched. They can swim better than they can run, so young screamers are usually raised in or near water, where they can better avoid predators. Like ducks, screamer chicksimprint early in life. That, and their unspecialized omnivorous diet makes them amenable to domestication. They can be excellent guard animals, due to their loud alarm calls ("screams") when encountering anything new and possibly threatening.
Both the southern and the horned screamer remain widespread and are overall fairly common.[7][8] In contrast, the northern screamer is relatively rare and consequently considerednear threatened.[9] They are seldomhunted, in spite of their conspicuous nature, because their flesh has a spongy texture and is riddled with air-sacs, making it highly unpalatable.[citation needed] The main threats arehabitat destruction and increased intensification of agriculture.[9]
