Great Bustard (Otis tarda)

[order] OTIDIFORMES | [family] Otididae | [latin] Otis tarda | [UK] Great Bustard | [FR] Grande Outarde | [DE] Grosstrappe | [ES] Avutarda Europea | [NL] Grote Trap

Subspecies

Physical charateristics

Large, grey-and-brown bustard. Grey head and neck, brown barred black above. White underparts with reddish-brown breast-band, developing with age in males. Upright stance and deliberate walk. In flight, powerful regular wing beats resemble an eagle, but does not glide.

Listen to the sound of Great Bustard

[audio:http://www.aviflevoland.nl/sounddb/G/Great Bustard.mp3]

Copyright remark: Most sounds derived from xeno-canto

Range

Eurasia : Eastcentral, Westcentral

Habitat

rather flat countryside. They seem to have moved from primeval landscapes like the Russian steppes to open agricultural land, especially traditional extensive farmland in dry regions. Birds in Iberia inhabit mixed forms of pasture, arable and fallow land, while those in Hungary live in pannonic grasslands, both pastures and secondary grassland (puszta), intermixed with agricultural land. Throughout the range the majority of clutches are found in agricultural habitats, often cereal crops. A certain amount of fallow land, e.g. fallow plots, set-aside plots, margins, etc., is necessary to provide food resources, especially insects, and for cover. Early-mown alfalfa, especially where intermixed with cereals, reduces breeding density.

The wintering habitat is mostly large fallow plains of alfalfa and rape Brassica napus.

Reproduction

The nest is on the ground, generally on patches of bare soil in cereal fields or grassland. The location is chosen by the female, and is usually in the vicinity of the display grounds which are on open areas with low vegetation in agricultural land (often winter-sown). A low level of disturbance is essential for successful breeding. The Great Bustard usually lays two eggs (more rarely one or three, exceptionally more), which are incubated for 25-27 days. The female is very likely to leave the clutch following disturbance, especially at the beginning of the breeding period. Chicks are led by the female parent during the first months of their life and may stay with females until the next courtship period.

Feeding habits

The chicks rely on insects for the first months of their life, and the adults eat insects and plants. During winter birds feed mainly on Brassicaceae and alfalfa Medicago sativa, especially seeds which are found on the ground after harvesting. In spring and summer they eat mainly plant material (chiefly leaves and inflorescences, but also buds, shoots and seeds) as well as insects and even small vertebrates.

Conservation

This species has suffered rapid population reductions across most of its range owing to the loss and fragmentation of its habitat. Although populations in its Iberian stronghold have stabilised and possibly increased, future land-use changes in eastern Europe, Russia and central Asia may have a significant impact on this species’s population and the extent of its remaining habitat, such that it is likely to undergo a rapid population reduction over the next three generations. It therefore qualifies as Vulnerable.
This globally threatened bustard has a wide but very fragmented distribution in Eurasia, from north-western Morocco and the Iberian Peninsula to central Siberia and Mongolia. From the natural steppe it has become adapted to cultivated areas, but since the middle of last century its populations are declining and its breeding area is contracting. The population of the European Union amounts 13500-14000 breeding pairs, but nearly all these birds inhabit the Iberian Peninsula. Notwithstanding increasing protection measures, it doesn’t withstand intensification of agriculture

Migration

Migratory in east, dispersive or resident elsewhere. Iberian population shows least movement, though some of local nature. In central Europe, basically resident or locally dispersive in mild, snow-free winters, but in severe winters northern flocks in particular liable to be displaced over several hundred km. Cold-weather movements most marked in north-central Europe, in which conditions German birds move west, some as far as North Sea countries. In contrast, truly migratory in FSU, except in southern Ukraine where resident. These migrants winter southern Ukraine and south of breeding range in parts of Near East and Middle East: from Syria, through northern Iraq eastwards into Iran and Transcaucasia. Present all year in Turkey, and uncertain whether any movement to, from or through that country. Autumn migration protracted; in northern parts of FSU, some birds (probably immatures) start moving in August while others stay until heavy snow covers ground; main passages early October to mid-December. Spring return begins early, and proceeds more quickly than autumn exodus. Northward movement through Ukraine and Transcaucasia from early March (peak mid-March), and winter flocks gone from southern steppes by end March or early April; breeding grounds reoccupied by mid-April.

Distribution map