great bittern

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.

Some populations are sedentary and stay in the same areas throughout the year. More northerly populations usually migrate to warmer regions but some birds often remain; birds in northern Europe tend to move south and west to southern Europe, northern and central Africa, and northern Asian birds migrate to parts of the Arabian peninsula, the Indian sub-continent, and the provinces of Heilongjiang, Jilin and Inner Mongolia in eastern China.Outside the breeding season it has less restrictive habitat requirements, and as well as living in reed beds, it visits rice fields, watercress beds, fish farms, gravel pits, sewage works, ditches, flooded areas and marshes.
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.

Eurasian Bittern feeds mainly on fish, but also on insects, amphibians, worms, small mammals and birds.

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.

The Eurasian bittern or great bittern (Botaurus stellaris) is a wading bird in the bittern subfamily (Botaurinae) of the heron family Ardeidae. There are two subspecies the northern race (B. s. stellaris) breeding in parts of Europe and across the Palearctic as well as on the northern coast of Africa while the southern race (B. s. capensis) is endemic to parts of southern Africa. It is a secretive bird seldom seen in the open as it prefers to skulk in reed beds and thick vegetation near water bodies. Its presence is apparent in the spring when the booming call of the male during the breeding season can be heard. It feeds on fish small mammals fledgling birds amphibians crustaceans and insects. The nest is usually built among reeds at the edge of bodies of water. The female incubates the clutch of eggs and feeds the young chicks which leave the nest when about two weeks old. She continues to care for them until they are fully fledged some six weeks later. With its specific habitat requirements and the general reduction in wetlands across its range the population is thought to be in decline globally. However the decline is slow and the International Union for Conservation of Nature has assessed its overall conservation status as being of "least concern". Nevertheless some local populations are at risk and the population of the southern race has declined more dramatically and is cause for concern. In the United Kingdom it is one of the most threatened of all bird species. Usually solitary the Eurasian bittern forages in reed beds walking stealthily or remaining still above a body of water where prey may occur. It is a shy bird and if disturbed often points its bill directly upwards and freezes in that position causing its cryptic plumage to blend into the surrounding reeds an action known as bitterning. While in this position the shield of elongated feathers on throat and breast droop downwards and hide the neck so that the outline of the head and body is obscured. Sometimes it resorts to applying powder down produced by patches of specialist down feathers at the side of its breast. This white dusty material seems to help it to rid its head and neck of slime after feeding on eels. It then removes the excess powder by scratching vigorously before applying preen oil from the gland at the base of its tail. The bird has a secretive nature keeping largely hidden in the reeds and coarse vegetation. Occasionally especially in hard winter weather it stands in the open beside the water's edge although usually close to cover to facilitate a hasty retreat. In flight its wings can be seen to be broad and rounded and its legs trail behind it in typical heron fashion. Its neck is extended when it takes off but is retracted when it has picked up speed. It seldom flies however except when feeding young preferring to move through the vegetation stealthily on foot. Its gait is slow and deliberate and it can clamber over reeds by gripping several at a time with its toes. It is most active at dawn and dusk but also sometimes forages by day. Eurasian bitterns feed on fish small mammals amphibians and invertebrates hunting along the reed margins in shallow water. British records include eels up to 35 cm (14 in) and other fish mice and voles small birds and fledglings frogs newts crabs shrimps molluscs spiders and insects. In continental Europe members of over twenty families of beetle are eaten as well as dragonflies bees grasshoppers and earwigs. Some vegetable matter such as aquatic plants is also consumed. Males are polygamous mating with up to five females. The nest is built in the previous year's standing reeds and consists of an untidy platform some 30 cm (12 in) across. It may be on a tussock surrounded by water or on matted roots close to water and is built by the female using bits of reed sedges and grass stalks with a lining of finer fragments. The eggs average 50 by 40 mm (2 by 1+1&frasl2 in) in size and are non-glossy olive-brown with some darker speckling at the broader end. Four to six eggs are laid in late March and April and incubated by the female for about twenty-six days. After hatching the chicks spend about two weeks in the nest before leaving to swim amongst the reeds. The female rears them without help from the male regurgitating food into the nest from her crop the young seizing her bill and pulling it down. They become fully fledged at about eight weeks.