Eurasian Bittern
Botaurus stellaris
Pelecaniformes Order – Ardeidae Family
BIOMETRICS:
Length: 64-80 cm
Weight: 865-1940 g
DESCRIPTION:
Eurasian Bittern has yellowish-brown plumage on upperparts, with golden patches mottled and streaked black. On the wings, primaries are reddish-orange. Tail is similar. Both are streaked and speckled with black. Some elongated feathers situated on rear neck and shoulders may erect when necessary.
Underparts are paler, with vertical dark streaks. Breast, belly and flanks are heavily streaked with reddish-brown. Throat is pale yellowish-brown.
On the head, crown and nape are black, and we can see a blackish moustache, starting from the base of the bill and extending down to the head sides. Lores’ colour varies according to the season.
The long and pointed bill is yellowish-green. Eyes are yellow or reddish-orange. Legs and feet are greenish.
Both sexes are similar.
Juvenile resembles adults, with streaked brown crown and moustache, less marked mantle and scapulars, and paler wing coverts.
DIET:
Eurasian Bittern feeds mainly on fish, but also on insects, amphibians, worms, small mammals and birds.
PROTECTION / THREATS / STATUS:
Eurasian Bittern populations are in decline, due mainly to habitat loss, and they are now often confined in natural reserves. Drainage of wet areas and human disturbances play an important role in this decline.
Populations of this species are stable now, with good protection, but their habitat needs also great attention.
Fr: Butor étoilé
All : Rohrdommel
Esp : Avetoro Común
Ital : Tarabuso eurasiatico
Nd : Roerdomp
Russe : Большая выпь
Sd: Rördrom
Photographer:
Aurélien Audevard
OUESSANT DIGISCOPING
José Luis Beamonte
Pájaros de España
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
BIRDS OF AFRICA SOUTH OF THE SAHARA by Ian Sinclair and Peter Ryan - Princeton University Press Princeton and Oxford - ISBN: 0691118159
THE HANDBOOK OF BIRD IDENTIFICATION FOR EUROPE AND THE WESTERN PALEARCTIC by Mark Beaman, Steve Madge - C.Helm - ISBN: 0713639601
THE COMPLETE BOOK OF BRITISH BIRDS – Written by “Royal Society for the Protection of Birds” experts - Préface de Magnus Magnusson - Michael Cady- Rob Hume Editors - ISBN: 0749509112
BIRDS OF THE MIDDLE EAST by R.F. Porter, S. Christensen, P Schiermacker-Ansen C.Helm - ISBN: 0713670169
BirdLife International (BirdLife International)
Eurasian Bittern spends most of its time hidden in reedbeds or dense aquatic vegetation. It may feed in open area, but not so far from cover where it runs to hide if alarmed. This bird moves easily among reed stems, with its long feet grabbing the reeds. It is very agile, and its long toes allow it to climb, but also to walk on floating vegetation. Its streaked plumage provides it an excellent camouflage.
Eurasian Bittern is able to adopt several postures, according to the moment. When weather is cold, it deeps its neck and fluffs its plumage, and becomes as a big egg. When disturbed, it adopts an erect posture among reeds with held neck, head and bill upwards. At this time, the bird is almost similar to its environment. It watches with its turning orange eyes, body and head staying motionless.
Birds disturbed at nest fluff their feathers, extending the wings on the ground, and rising neck and head with bill pointed upwards. It stays in this posture and it sways as the reeds with the wind. It may stay several hours, until threat gone away.
VOICE: SOUNDS BY XENO-CANTO
Eurasian Bittern male’s most commonly call is often given at dusk and dawn, and it is a characteristic slow, deep, resonant and far-carrying booming, and preceded by 1 to 3 short cough “up-RUMBH” or “up-up-RUMBH”, repeated 3 to 4 times.
This call is uttered with head forwards, entire body vibrating and with open bill, in order to aspirate the air, and then, the bird rises its head and neck, and exhales this air, producing this strange noise.
We can also hear a nasal “kau” as large gull call, or some barking. This call is often heard in flight in autumn.
HABITAT:
Eurasian Bittern lives in freshwater or brackish marshes, with extensive reedbeds, often in lowlands. In winter, they may move from a reedbed to other, but bitterns move only in very hard winters, and leave their usual area for another.
Juveniles perform extensive dispersions after the breeding season, sometimes of several hundreds of kilometres.
RANGE:
Eurasian Bittern breeds in Europe, from Sweden to Spain, throughout Great Britain. It is also found in Eastern Europe, Asia to Pacific Ocean, and also locally in Africa (Algeria and South Africa).
BEHAVIOUR:
Eurasian Bittern feeds in shallow water, by stalking. It walks slowly in water, close to the shore of the reedbed, stopping frequently. It stays motionless during long time, watching and searching for preys such as fishes, amphibians and aquatic insects. It walks with head slightly deep into shoulders, and with a light lateral side to aim better at the prey. It approaches with very slow movements, holding the neck and suddenly, it seizes or jabs the prey with its bill. Prey is shacked several times before to be swallowed head first.
If Eurasian Bittern is alarmed, it may attack. It is a solitary bird outside breeding season. It defends a large part of reedbed against other males. Males are very aggressive and may fight very strongly, with mortal pecks to opponents. During these fights, males fluff neck and shoulders’ long feathers, and open their wings in front of each other. They also perform aerial fights, encircling and challenging each other with their sharp-edged bills.
Courtship display starts with the characteristic booming call. Eurasian Bittern performs flight and fluffed feathers displays. But, according to the hidden life of this species, courtship displays are almost unknown.
Eurasian Bittern defends the nest-site against intruders, other males of the same species, but also against raptors flying over its territory. It may fly rapidly, and it is able to chase away the birds of prey.
Eurasian Bittern has to clean its plumage after killing some fishes and eels. These animals leave a kind of mucus on the Bittern’s feathers. It has two areas in its body covered with short down, producing a white dust. So, Bittern rubs head and neck under shoulders during 10 to 35 seconds, and both go out almost white. Then, Bittern preens its feathers to remove mixed dust and mucus. This cleaning may last up to 45 minutes, and it performs it several times a day.
FLIGHT:
Eurasian Bittern rises clumsily with extended neck. It flies low over reeds for short distance, before dropping back into cover. In steady flight, neck is retracted as other herons’ species. Broad wings show rounded tips.
REPRODUCTION:
Eurasian Bittern nests in reedbeds. Nest is a floating platform made with dry bits of reeds and aquatic plants, lined with finer materials, and secured with some stems to the reedbed. Nest is well concealed into vegetation and built by female alone.
Adults alight at some distance from the nest, and walk to it, forming a small path. Female uses it, walking with head held forwards.
In early March, female lays 4 to 6 greenish-brown eggs, spotted with brown, at intervals of 2 to 3 days. Incubation starts with the first egg laid, and lasts about 26 days, by female. Altricial chicks are covered with reddish-brown down. They are fed only by female (males are polygamous), with regurgitated food into the nest.
Young begin to leave the nest at about 2-3 weeks, moving into the surrounding vegetation. They may adopt typical alarm posture with held head upwards at 8 days of age. They reach their entire plumage when they are 8 weeks old. They are able to fly and they disperse throughout July. At this time, they can find their own food. They gather with other migratory Bitterns in other reedbeds in autumn and winter. If they stay alive, they find again their natal reedbed the next year.
Young reach their sexual maturity at one year.
