Avetoro Común

Identificación

Bitterns are thickset herons with bright, pale, buffy-brown plumage covered with dark streaks and bars. As its alternative name suggests, this species is the largest of the bitterns, with males being rather larger than females. The Eurasian or great bittern is 69–81 cm (27–32 in) in length, with a 100–130 cm (40–50 in) wingspan and a body mass of .mw-parser-output .frac{white-space:nowrap}.mw-parser-output .frac .num,.mw-parser-output .frac .den{font-size:80%;line-height:0;vertical-align:super}.mw-parser-output .frac .den{vertical-align:sub}.mw-parser-output .sr-only{border:0;clip:rect(0,0,0,0);clip-path:polygon(0px 0px,0px 0px,0px 0px);height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;width:1px}0.87–1.94 kg (1 lb 14+1⁄2 oz – 4 lb 4+1⁄2 oz).<p>The crown and nape are black, with the individual feathers rather long and loosely arranged, tipped with buff narrowly barred with black. The sides of the head and neck are a more uniform tawny-buff, irregularly barred with black. The mantle, scapulars and back are of a similar colour but are more heavily barred, the individual feathers having black centres and barring. The head has a yellowish-buff superciliary stripe and a brownish-black moustachial stripe. The sides of the neck are a rusty-brown with faint barring. The chin and throat are buff, the central feathers on the throat having longitudinal stripes of rusty-brown. The breast and belly are yellowish-buff, with broad stripes of brown at the side and narrow stripes in the centre. The tail is rusty-buff with black streaks in the centre and black mottling near the edge. The wings are pale rusty-brown irregularly barred, streaked and mottled with black. The plumage has a loose texture, and elongated feathers on the crown, neck and breast can be erected. The powerful bill is greenish-yellow with a darker tip to the upper mandible. The eye has a yellow iris and is surrounded by a ring of greenish or bluish bare skin. The legs and feet are greenish, with some yellow on the tarsal joint and yellow soles to the feet. Juveniles have similar plumage to adults but are somewhat paler with less distinct markings.

Taxonomía

This species was first described as Ardea asteria sive stellaris as early as 1603 by Ulisse Aldrovandi in his Ornithologiae. In 1660 the ornithologist Thomas Browne referred to it as Ardea stellaris botaurus and then the Swedish naturalist Carl Linnaeus in his Systema Naturae of 1758 named it again as Ardea stellaris. It is placed in the subfamily Botaurinae, and its closest relatives are the American bittern (Botaurus lentiginosus), the pinnated bittern (Botaurus pinnatus) and the Australasian bittern (Botaurus poiciloptilus). Two races of Eurasian bittern are recognised; the nominate subspecies B. s. stellaris has a palearctic distribution and occurs across a broad swathe of Europe, North Africa and Asia, while the other subspecies, B. s. capensis, occurs only in southern Africa. The name capensis was used for species found in the Afrotropics for which no exact range was known.<p>The generic name Botaurus was given by the English naturalist James Francis Stephens, and is derived from Medieval Latin butaurus, "bittern", itself constructed from the Middle English name for the bird, botor. Pliny gave a fanciful derivation from Bos (ox) and taurus (bull), because the bittern's call resembles the bellowing of a bull. The species name stellaris is Latin for "starred", from stella, "star", and refers to the speckled plumage.<p>Its folk names, often local, include many variations on the themes of "barrel-maker", "bog-bull", "bog hen", "bog-trotter", "bog-bumper", "mire drum[ble]", "butter bump", "bitter bum", "bog blutter", "bog drum", "boom bird", "bottle-bump", "bull of the bog", "bull of the mire", "bumpy cors", and "heather blutter". Most of these were onomatopoeic colloquial names for the bird; the call was described as "bumping" or "booming". Mire and bog denote the bird's habitat.

Nombre científico

Botaurus stellaris

Autoridad

(Linnaeus, 1758)

Orden

Pelecaniformes

Familia

Ardeidae

Género

Botaurus

Distribución y hábitat

The breeding range of B. s. stellaris extends across temperate parts of Europe and Asia from the British Isles, Sweden and Finland eastwards to Sakhalin Island in eastern Siberia, Korea and Hokkaido Island in Japan. The bird's northern extent of occurrence is around 57°N in the Ural Mountains and 64°N in eastern Siberia. Its southern limit is the Mediterranean Sea, the Black Sea, Iran, Afghanistan, Kazakhstan, Mongolia and Hebei Province in northern China. Small resident populations also breed in Morocco, Algeria and Tunisia. 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, but for preference, chooses large reed beds of at least 20 hectares (50 acres) in which to breed.<p>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.<p>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. This population is sedentary.

Área de cría

Ampliamente distribuida en la región paleártica.

Área no reproductiva

AF, n OR

Migración

Migrantes completos

Comportamiento

Patrón migratorio: Migrantes completos.

Conservación

Tendencia poblacional: en declive.

Tendencia poblacional

en declive