Bitterns are thickset herons with bright, pale, buffy-brown plumage covered with dark streaks and bars, similar in appearance to the American Bittern, Botaurus lentiginosa. As its alternate name (Great Bittern) suggests, this species is the largest of the bitterns. The Eurasian is 69-81 cm (27-32 in) in length, with a 100-130 cm (39-51 in) wingspan and a body mass of 0.87-1.94 kg (1.9-4.3 lb). If it senses that it has been seen, it points its bill directly upwards and becomes motionless so that its cryptic plumage causes it to blend into the surrounding reeds: an action known as bitterning. It is most active at dawn and dusk.
Habitat and Distribution
Distribution in Europe as a whole is estimated at 20-44,000 males. It usually inhabits Phragmites reedbeds. The population is declining in much of its temperate European and Asian range. It is resident in the milder west and south, but migrates south from areas where the water freezes in winter. In the UK, the main areas are Lancashire and East Anglia with an estimated 44 breeding pairs. 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
Usually solitary, the Great Bittern forages in reedbeds, walking stealthily or remaining still above a body of water where prey may occur. Bitterns feed on fish, eels, amphibians and invertebrates, hunting along the reed margins in shallow water.
Males are polygamous with each mating with up to five females. The nest is built in the previous year's standing reeds and consists of a platform some 30 cm across. Four or five eggs are laid in late March and April and incubated by the female bird. After hatching, the chicks spend about two weeks in the nest and then disperse amongst the reeds.
Calls and Songs
The mating call or contact call of the male is a deep fog-horn or bull-like boom, easily audible from a distance of 3 miles on a calm night. This call is mainly given between January and April.