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Botaurus pinnatus

Pinnated Bittern


Botaurus pinnatus

(Wagler, JG, 1829)
Mirasol Grande
Socó-boi-baio

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

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Synonyms: Ardea pinnata.

Subspecies:





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Records from Itapúa

Conservation status according to BirdLife International: Least Concern


Description


This is a large, heavily barred wading bird belonging to the Ardeidae family, reaching an overall length of 63 to 76 centimeters and weighing between 800 and 1000 grams. Its plumage displays an intricate, highly cryptic pattern of buff, dark brown, and creamy white streaks and bars, which provides exceptional camouflage within marshland vegetation. The crown is dark, almost blackish, contrasting with a whitish throat that features distinctive vertical brownish streaks. The powerful, dagger-like bill is greenish-yellow, while the large, forward-facing eyes boast a striking pale yellow iris. Unlike many other herons, it has a thick, muscular neck with specialized ruff feathers on the sides that can be flared during territorial displays or when threatened.

Geographical distribution: It is patchily distributed throughout the Neotropical region. Its geographic range extends from southeastern Mexico and various localized areas in Central America, including Costa Rica and Panama, down to a vast portion of South America. On this continent, it is found across the river basins of Colombia, Venezuela, the Guianas, large parts of Brazil, Paraguay, Uruguay, and northern Argentina. Two subspecies are currently recognized: Botaurus pinnatus cabanisi, which is restricted to Central America, and Botaurus pinnatus pinnatus, which occupies the broader South American range.

Habitat: It primarily inhabits freshwater wetlands densely covered with emergent vegetation, such as marshes, swamps, flooded grasslands, rice paddies, and the margins of slow-flowing rivers. It shows a strong preference for areas dominated by plants like Typha and Cyperus, where the tall herbaceous cover allows it to remain completely undetected. Open water bodies are generally avoided, as the species prefers shallow waters ranging from 30 to 50 centimeters deep, which facilitates its stealthy wading and foraging strategies.

Feeding: It possesses a strictly carnivorous and highly opportunistic diet. Its prey spectrum consists of a wide variety of aquatic and terrestrial organisms captured along wet margins. It regularly consumes freshwater fish, amphibians (including adult frogs and tadpoles), small reptiles such as water snakes, small mammals like wild rodents, and a diverse array of invertebrates including crabs, dragonflies, beetles, and grasshoppers. It hunts using a sit-and-wait ambush technique, remaining motionless for long periods before striking forward with lightning speed using its sharp bill.

Behavior: This species is remarkably shy, solitary, and primarily crepuscular or nocturnal, though it may forage during overcast days. When detecting danger or an approaching threat, it immediately adopts the classic bittern posture, stretching its neck vertically with the bill pointing straight up; in this position, it sways gently from side to side, mimicking reeds blowing in the wind. During the breeding season, males produce a deep, resonant territorial call, described as a hollow booming or puffing sound, generated by inflating the esophagus, which can carry over long distances across the marsh.

Nesting: The breeding process is carried out solitarily, and the species does not form nesting colonies. It constructs a simple, flat platform nest made of dry reeds, rushes, and other aquatic grasses, situated slightly above the water level or nestled deep within thick vegetation to prevent flooding. The female typically lays a clutch of 2 to 3 eggs that are pale olive-green or brownish in color. Incubation is performed almost exclusively by the female for a period of 24 to 26 days. The chicks, covered in yellowish down, are fed by regurgitation and remain under maternal care until they are old enough to fledge and employ their own camouflage.

Conservation status: It is currently classified as Least Concern (LC) on the IUCN Red List of Threatened Species. Despite its extensive geographic range, local populations are facing localized declines due to the ongoing drainage, fragmentation, and degradation of wetland ecosystems. These threats are driven by agricultural expansion, river channelization, and the heavy use of pesticides and fertilizers in commercial rice farming.



Compilation and publication: EcoRegistros – 10/08/2026




Geographic distribution


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Species photographs

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Foto
Photography ID: 400760
  Adult

Coronel Bogado
Itapúa
Paraguay
04/14/2013
Roberto Fermín Derna



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Page 1
Record IDDateExact timeCountryProvince / departmentPlaceFilmedPhotographedRecorded vocalObservedHeardWounded or deadNumber of individualsUser or BibliographyDetail
124849414/04/2013ParaguayItapúaCoronel BogadoRoberto Fermín Derna
Page 1

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Recommended citation
Please use the following reference when citing this species account.
EcoRegistros. 2026. Pinnated Bittern (Botaurus pinnatus) – Species account. Accessed from www.ecoregistros.org on 14/09/2026.