| Sunbittern | |
|---|---|
.JPG) | |
| onCristalino River Southern Amazon, Brazil | |
| Vocalization | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Eurypygiformes |
| Family: | Eurypygidae Selby, 1840 |
| Genus: | Eurypyga Illiger, 1811 |
| Species: | E. helias |
| Binomial name | |
| Eurypyga helias (Pallas, 1781) | |
_Area.svg) | |
| Sunbittern range | |
| Synonyms[2] | |
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Thesunbittern (Eurypyga helias) is abittern-like bird of tropical regions of the Americas, and thesole member of thefamilyEurypygidae (sometimes spelledEurypigidae) andgenusEurypyga. It is found in Central and South America, and has threesubspecies. The sunbittern shows both morphological and molecular similarities with thekagu (Rhynochetos jubatus) ofNew Caledonia, indicating aGondwanan origin, both species being placed in thecladeEurypygiformes.[3]
The sunbittern was traditionally placed in theGruiformes, but this was always considered preliminary. Altogether, the bird is most similar to another bird that was provisionally placed in the Gruiformes, thekagu (Rhynochetos jubatus).[4][5] Molecular studies seem to confirm that the kagu and sunbittern are each other's closest living relatives and have a similar wing display.[6][7] They are probably not Gruiformes (though the proposedMetaves are just as weakly supported).[8] Altogether, the two species seem to form a minorGondwanan lineage which could also include the extinctadzebills and/or themesites, and is of unclear relation to the Gruiformes proper. Notably, the kagu and mesites also havepowder down.
An indeterminate fossil eurypygid has been documented from theGreen River Formation ofWyoming, USA. This specimen, known from a full skeleton, is the oldest and only known fossil of the group, and suggests that eurypygids had a much more northernly range in the past. This specimen has been figured in several studies, and was given the unofficial name "Eoeurypyga olsoni" in a 2003 dissertation, but as-of-yet remains unnamed.[9][10]
The sunbittern was formerly treated as two species (E. helias andE. major), but now they are treated as a single species with considerable variation between thesubspecies. The three subspecies are recognised on the basis of plumage characters and size. The three subspecies areallopatric.[3]
The sunbittern'srange extends fromGuatemala toBrazil. The nominate race,E. h. helias, is found east of the Andes in lowland tropical South America, from theOrinoco basin, through theAmazon basin andPantanal. The subspeciesE. h. meridionalis, has a more restricted distribution, being found along the East Andean slope in south-centralPeru, in the lower subtropical zone at altitudes of 800–1,830 m (2,620–6,000 ft). The final subspecies,E. h. major, is found at various altitudes ranging from southernGuatemala, through Central America and theChocó to westernEcuador.[3] This subspecies may also be present in southernMexico. It has been traditionally reported from the Atlantic slope ofChiapas, but no specimens are known and there have been no recent records.[11]
The species is found in the humidNeotropical forests, generally with an open understorey and near rivers, streams, ponds or lagoons.[3]
The bird has a generally subdued coloration, with fine linear patterns of black, grey and brown. Itsremiges however have vividly colored middle webs, which with wings fully spread show bright eyespots in red, yellow, and black. These are shown to other sunbitterns in courtship and threat displays, or used to startle potential predators. Male and female adult sunbitterns can be differentiated by small differences in the feather patterns of the throat and head. Like some other birds, the sunbittern haspowder down.
The sunbittern has a long and pointed bill that is black above, and a shorthallux as in shorebirds and rails. In the South American subspecies found in lowlands east of theAndes, the upperparts are mainly brown, and the legs and lower mandible are orange-yellow. The two other subspecies are greyer above, and their legs and bill are sometimes redder.[3]
They are cryptic birds that display their large wings, that exhibits a pattern that resemble eyes, when they feel threatened.
The sunbittern consumes a wide range of animal prey. Insects form an important part of the diet, with cockroaches, dragonfly larvae, flies, katydids, water beetles and moths being taken. Other invertebrate prey includes crabs, spiders, shrimps and earthworms. They will also take vertebrate prey including fish, tadpoles, toads and frogs, eels and lizards.[3]
Sunbitterns are one of 12 species of birds in five families that have been described as fishing using baits or lures to attract prey to within striking distance. This type of behaviour falls within the common definition oftool use. In sunbitterns this behaviour has only been observed in captive birds so far.[12]
Sunbitterns start nesting in the early wet season and before it starts they make flight displays 10–15 m (33–49 ft) high in the forest canopy. They build open nests in trees, and lay two eggs with blotched markings. The young areprecocial, but remain in the nest for several weeks after hatching.[3][13]
