It is a secretive bird, seldom seen in the open as it prefers to skulk in reed beds and thick vegetation near water bodies.

[15] Bitterns are thickset herons with bright, pale, buffy-brown plumage covered with dark streaks and bars.

[19] It typically inhabits reed beds (Phragmites) and swamps, as well as lakes, lagoons and sluggish rivers fringed by rank vegetation.

It sometimes nests by ponds in agricultural areas, and even quite near habitations where suitable habitat exists,[18] but for preference, chooses large reed beds of at least 20 hectares (50 acres) in which to breed.

[1] The subspecies B. s. capensis is endemic to southern Africa, where it is found sparingly in marshes near the east coast, the Okavango Delta and the upland foothills of the Drakensberg Mountains.

[1] 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.

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.

[18] 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.

The chief threat the bird faces is destruction of reed beds and drainage and disturbance of its wetland habitats.

[25] The Lancashire population at Leighton Moss RSPB reserve declined in recent decades,[27] while bitterns have been attracted to new reed beds in the West Country.

[29] In the 21st century, bitterns are regular winter visitors to the London Wetland Centre, enabling city dwellers to view these scarce birds.

[30] In Ireland, it died out as a breeding species in the mid-19th century, but in 2011 a single bird was spotted in County Wexford and there have been a number of subsequent sightings.

[12] The Eurasian bittern is proposed as one of rational explanations behind the drekavac, a creature of the graveyard and darkness originating in south Slavic mythology.

[33] The 18th-century Scottish poet James Thomson refers to the bittern's "boom" in his poem "Spring" (written 1728), published as part of his The Seasons (1735):[34] The Bittern knows the time, with bill ingulphtTo shake the sounding marsh[34]The species is mentioned in George Crabbe's 1810 narrative poem The Borough, to emphasise the ostracised, solitary life of the poem's villain, Peter Grimes:[35] And the loud Bittern from the bull-rush homeGave from the Salt-ditch side the bellowing boom:[35]The Irish poet Thomas MacDonagh translated the Gaelic poem "The Yellow Bittern" ("An Bonnán Buí" in Irish) by Cathal Buí Mac Giolla Ghunna.

[36][37] His friend, the poet Francis Ledwidge, wrote a "Lament for Thomas MacDonagh" with the opening line "He shall not hear the bittern cry".

Because of its secretive and skulking nature, it was for long unclear exactly how the bittern produced its distinctive booming call.

A Mediaeval theory held that the bittern thrust its beak into the boggy ground of the marsh in which it lived, making its vocalization which was amplified and deepened as it reverberated through the water.

A reference to this theory appears in 1476 in Chaucer's The Wife of Bath's Tale, lines 972-73:[40] And, as a bitore bombleth in the myre,She leyde hir mouth un-to the water doun[40]The English 17th century physician Sir Thomas Browne disputed this claim, stating in his Pseudodoxia Epidemica, Book III, Ch.27: "That a Bittor maketh that mugient noise, or as we term it Bumping, by putting its bill into a reed as most believe, or as Bellonius and Aldrovandus conceive, by putting the same in water or mud, and after a while retaining the air by suddenly excluding it again, is not so easily made out.

[43] The zoologist Hugh Cott, in his classic 1940 study of camouflage, Adaptive Coloration in Animals, cites William Palmer's account of seeing a bittern:[44][45] he once marked the place in a marsh where one of these birds had alighted: on reaching the spot he had the "greatest difficulty in finding it clinging motionless, with bill almost erect, to a stem of wild oats".