Fr: Butor mirasol
Ang: Pinnated Bittern
All: Schuppenhals-Rohrdommel
Esp: Avetoro Mirasol
Ita: Tarabuso pinnato
Nd: Zuid-Amerikaanse Roerdomp
Sd: strimmig rördrom
Photographers:
Roger Ahlman
Pbase Galleries Peru and Ecuador
Otto Plantema
Trips around the world
Dubi Shapiro
Dubi Shapiro Photo Galleries
Text by Nicole Bouglouan
Sources:
HANDBOOK OF THE BIRDS OF THE WORLD vol 1 by Josep del Hoyo-Andrew Elliot-Jordi Sargatal - Lynx Edicions - ISBN: 8487334105
A GUIDE TO THE BIRDS OF MEXICO AND NORTHERN CENTRAL AMERICA by Steve N. G. Howell, Sophie Webb - Oxford University Press - ISBN: 0198540124
PORTRAITS D’OISEAUX GUYANAIS - Groupe d'étude et de protection des oiseaux en Guyane (GEPOG) - Ibis rouge éditions - ISBN: 2844501842
Birds of Nicaragua: A Field Guide De Liliana Chavarría-Duriaux, David C. Hille, Robert Dean – Editeur: Cornell University Press, 2018 – ISBN: 150170950X, 9781501709500 – 480 pages
Birds of Venezuela de David Ascanio, Gustavo Rodriguez, Robin Restall – Editeur: Bloomsbury Publishing, 2017 – ISBN: 1472925661, 9781472925664 – 544 pages
BIRDS OF VENEZUELA by Steven L. Hilty – Ed. Christopher Helm – ISBN: 0713664185
The Pinnated Bittern, Botaurus pinnatus, in Paraguay
Botaurus pinnatus (Pinnated Bittern)
SORA - A new subspecies of the Pinnated Bittern
Heron Conservation - South American Bittern
Birds Colombia - Avetoro/Pinnated Bittern/Botaurus pinnatus
Arthur Grosset's Birds (Arthur Grosset)
Wikipedia, the free encyclopaedia
Pinnated Bittern
Botaurus pinnatus
Ordre des Pélécaniformes – Famille des Ardéidés
INTRODUCTION:
The Pinnated Bittern is also named South American Bittern. It is found from S Mexico to N Argentina, with a scattered distribution through Central America and N South America. Two subspecies share the range.
The Pinnated Bittern is a typical Botaurus species, a large Ardeidae with cryptic buffy-brown plumage. It has skulking habits and frequents freshwater habitats with dense reed beds and well-vegetated areas where it can disappear almost completely except for the raised neck, head and long bill, sometimes visible among the reeds.
It is largely nocturnal and solitary, sometimes in small foraging groups in rich feeding areas. Its diet includes a variety of fish, reptiles, amphibians, small mammals and arthropods, caught after a long period waiting for prey.
The Pinnated Bittern is solitary nester and the female lays the eggs in a slightly cup-shaped platform made of reeds and other plants, and built relatively close to the water surface.
The Pinnated Bittern is described as uncommon or rare, but it is very secretive and difficult to see. The population is currently stable and the species is not globally threatened.
DESCRIPTION OF THE BIRD:
Biometrics:
Length: 64-74 cm
Weight: 584 g
The Pinnated Bittern has buff upperparts heavily striped and barred blackish, including the upperwing. The flight-feathers are dark and the tail is blackish-brown with mostly black central rectrices.
On the underparts, chin and throat are white. Foreneck and underparts are creamy to pale buff, but foreneck and breast sides are streaked brown.
There are white tufts on the breast sides, but they are often concealed, although they become conspicuous in threat behaviour and possibly during courtship displays.
When the bird is flying, the blackish-brown flight-feathers and the buff-tipped primary coverts contrast with the brown innerwing.
On the head, crown and neck show narrow blackish-brown barring. The ear-coverts are buffy-brown and we can see a narrow whitish supercilium. The forehead is sooty-brown. The lores are yellow-green.
The long, stout, pointed bill is pale yellow with dusky cutting edges and tip. The eyes are pale yellow, becoming sometimes darker during courtship, from orange-brown to cinnamon-rufous. Legs and feet are yellowish-green with long, curved, blackish claws.
The female has similar appearance but she is smaller than male. She has buffy to ochraceous banding or mottling on the central rectrices, instead of black in male.
The juvenile is paler and more reddish-ochre, with less conspicuously barred underparts.
SUBSPECIES AND RANGE:
The Pinnated Bittern has two subspecies.
B.p. pinnatus (described above) is found in El Salvador and SE Nicaragua to W Costa Rica, SW Colombia and W Ecuador, E to Trinidad and the Guianas, S Brazil to Paraguay, NE Argentina and Uruguay.
The species was also recorded in Bolivia and throughout Brazil, but the status is unclear.
B.p. caribaeus is found in E Mexico (Veracruz to Quintana Roo) and Belize.
The first specimen was collected at El Cantemo in Tabasco (Mexico) by Robert W. Dickerman on May 9, 1955.
It differs from nominate in being paler in colour, with reduced streaking on throat and flanks. The underparts are rather creamy-white than buffy in “pinnatus”. The upperparts are paler, more buffy to cream, and less deeply tan and ochraceous. The black areas of the feathers are somewhat reduced compared to “pinnatus”. On the bill, the culmen is average longer.
HABITAT:
The Pinnated Bittern frequents various freshwater habitats such as swamps and marshes, usually in flat, open areas. It is also found in dense reed beds and lake borders, flooded pastures with tall grass, and sometimes plantations of rice and sugar cane.
The habitat of this species is dominated by tall sedges, rushes, reeds or cattails, and water hyacinth of genus Eichornia.
The Pinnated Bittern is mainly found at low elevations, often below 400 metres in Venezuela, only up to 50 metres in W Ecuador, but up to 2,600 metres in E Andes of Colombia.
CALLS AND SONGS: SOUNDS BY XENO-CANTO
The Pinnated Bittern has a large range of calls, depending on the situation.
In territorial defence or advertising call, it produces a booming roar call described as “oong, kachoonk”. The alarm call is described as “kaawk-kaawk” but when the bird takes flight, it gives a “ro,ro,ro” call.
The territorial calls can be heard both day and night, but mainly at dusk, before and during the breeding season. The bird calls from the vegetal cover or occasionally at the edge of a reed bed.
BEHAVIOUR IN THE WILD:
The Pinnated Bittern is nocturnal, but mainly crepuscular. It is more active at dusk and dawn. However, it may occasionally feed and fly during the day.
It forages and feeds by walking slowly but very deliberately, or by creeping forwards, often in crouched posture and the body almost parallel with the ground. It often feeds alone, but also in small, loose groups at good feeding areas.
It feeds primarily on fish (Myrophis), frogs (Pseudis), snakes (Ophis) and various insect including dragonflies (Odonata) and bugs (Hemiptera).
While foraging, the neck is kept folded, but as soon as the bird is alarmed, the head is raised above the vegetation for better view.
The Pinnated Bitterns are solitary birds and only very loosely colonial, but usually not at all. They are strongly territorial during the breeding season, during which aerial combats may occur. Major and sometimes lethal wounds are caused by the birds stabbing at each other with the long, stout bill. During territorial and defensive behaviour, the male erects the white neck ruff feathers.
At the beginning of the breeding season, the male produces strong booming calls involving first a series of clicks and coughs, followed by a large breath with the head held forwards, and a deep, resonant boom call as it exhales. During this vocal behaviour, the entire body vibrates and the sound can be heard at a distance of 1-5 kilometres. This call is repeated several times to attract a female.
The nest of the Pinnated Bittern is a platform made with dried reeds and other plant material. It is built just above the water surface, in dense, herbaceous vegetation.
The Pinnated Bittern is not migratory in the north of the range, but it has been recorded performing some movements but only during the breeding season in the south, in more temperate regions.
The flight of this species is heavy with wingbeats mainly above body level.
Small groups of bitterns show sometimes flight activities for a short period of time during the mid-breeding season. This behaviour is suspected to have some territorial or courtship significance.
The Pinnated Bittern is rarely seen perched in trees, but it is quite able to climb reeds. When flushed, it attempts to escape by freezing, but it may also take flight over a short distance (150 metres) before dropping into the marshy vegetation.
REPRODUCTION OF THIS SPECIES:
The breeding season varies across the range, but more information is required.
This period takes place in July-October in Trinidad, in May-July in Mexico and Central America, in February-April in Brazil, and October in N Argentina.
The nest is a platform made with dry reeds and other plant material. It is built in herbaceous vegetation, just above water surface (25-50 centimetres). The nest-site is located in herbaceous rushes with tall, dense vegetation over standing water. But it may also be found in wetlands bordering rivers, rice fields and sugar cane fields. The solitary nests are placed in the dense vegetal cover.
The female lays 2-3 olive to straw-yellow eggs. The incubation is suspected to be performed only by the female during 24-25 days (observation at one nest). At hatching, the downy chicks are greyish-buff to yellow-buff, and the bare parts are pinkish-yellow. They leave the nest about 20-22 days after hatching, but the fledging period is unknown.
Even a few days after hatching, the chicks are able to adopt the typical anti-predatory frozen posture as the adults do. The Pinnated Bittern breeds almost exclusively during the wet season.
PROTECTION / THREATS / STATUS:
The Pinnated Bittern is described as rare or uncommon, but it is rarely seen due to its skulking habits and secretive nature, making it easily overlooked. The species can be quite numerous or rare, depending on places.
The global population is roughly estimated to number 50,000/499,999 mature individuals. It is suspected to be stable.
The Pinnated Bittern is not globally threatened at the moment, and currently, the species is evaluated as Least Concern.
