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Theristicus caudatus

Buff-necked Ibis


Theristicus caudatus

(Boddaert, P, 1783)
Bandurria Boreal
Curicaca

Family: Threskiornithidae
Order: Pelecaniformes
Class: Aves
Phylum / Division: Chordata
Kingdom: Animalia

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Synonyms: Scolopax caudatus.

Subspecies:





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Records from Las Lomitas

Conservation status according to BirdLife International: Least Concern


Description


Belongs to a group of medium to large-sized wading birds, reaching an overall body length of 27 to 30 inches (70 to 76 centimeters). It is characterized by its striking plumage, featuring a creamy-buff neck and breast, a contrasting dark chestnut crown, and a solid black abdomen. The upperparts and back are predominantly dark gray, while the wings exhibit a large, prominent white patch that is highly visible during flight. Its bill is long, decurved, and black, adapted perfectly for probing soils. The bare skin around the eyes and on the throat is charcoal-black, contrasting sharply with its bright reddish-pink legs and intense orange-red irises. Sexual dimorphism is negligible, though males may present slightly larger dimensions.

Geographical distribution: Occurs widely across the South American continent. Its geographic range stretches from northern areas in Colombia and Venezuela, through the Guianas, extending south across vast regions of Brazil, Bolivia, Paraguay, Uruguay, and reaching northern and central Argentina. While most populations are sedentary, local seasonal movements occur in response to regional rainfall patterns and water table fluctuations.

Habitat: Inhabits a diverse array of open and semi-open landscapes. It is frequently observed in humid savannas, temperate grasslands, pastures, marshy edges, agricultural fields, and seasonally flooded plains. It strictly avoids dense tropical rainforests and closed woodlands, as it requires open ground with low vegetation to forage efficiently and detect potential predators. It has also successfully colonized human-modified environments, such as suburban parks, ranchlands, and golf courses.

Feeding: Maintains an opportunistic, carnivorous diet. It feeds on a broad range of terrestrial invertebrates and small vertebrates, searching for prey by walking slowly and probing the soft soil or mud with its long bill. Its typical prey includes beetles, grasshoppers, spiders, earthworms, snails, frogs, lizards, and small rodents. The highly sensitive bill tip allows the bird to locate hidden prey through tactile perception beneath the earth´s surface.

Behavior: Exhibits highly social and gregarious tendencies, usually foraging and traveling in pairs or small flocks of up to several dozen individuals. It is famous for its extremely loud, metallic, and clattering vocalizations, described as a resonant cackling cry that is uttered both on the wing and while perched. It utilizes tall trees, utility poles, or rocky ledges as communal night roosts. Its flight is strong and direct, characterized by rapid wingbeats interspersed with short glides, keeping its neck and legs fully extended.

Nesting: Commences its breeding cycle in association with the onset of the local rainy season. It constructs a bulky, platform-like nest using dry sticks, twigs, and grass, placing it securely in the canopy of tall trees, on cliff ledges, or occasionally on human-made structures. The female typically deposits a clutch of two to three greenish-white eggs speckled with brown markings. Both parents share incubation duties for approximately 26 to 28 days and cooperatively rear the altricial chicks, feeding them via regurgitation.

Conservation status: Classified as a species of Least Concern (LC) on the IUCN Red List. This status is justified by its extensive geographical range, stable population trends, and high ecological resilience. The expansion of cattle ranching and deforestation for agriculture has actually created new suitable foraging areas, allowing this taxon to expand its local range, although heavy pesticide use and wetland drainage remain localized threats.



Compilation and publication: EcoRegistros – 17/07/2026




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Page 1
Record IDDateExact timeCountryProvince / departmentPlaceFilmedPhotographedRecorded vocalObservedHeardWounded or deadNumber of individualsUser or BibliographyDetail
59650025/07/2017ArgentinaFormosaHotel Portal del Oeste, Las LomitasRodolfo Seró
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Recommended citation
Please use the following reference when citing this species account.
EcoRegistros. 2026. Buff-necked Ibis (Theristicus caudatus) – Species account. Accessed from www.ecoregistros.org on 14/09/2026.