Birds in Bulgaria

L 96-119 cm, WS 180-222 cm. Breeds sparsely on bogs in boreal forests, in reedbeds in lakes or along rivers in forested areas, mainly in deserted regions. Long-distance migrant (arriving late Mar-1st half Apr, leaving 2nd half Sep). Spectacular dancing display mainly in spring by pair, or involving hundreds of birds (mostly imm.) at favoured sites: walking with erect, stiff neck, sometimes with raised wings, leaping into air with beating wings, bowing, picking up items from ground and tossing them up; freezes in erect posture before shaking plumage. Food plant material, grain, old potatoes, insects. Nest mound of vegetation.
IDENTIFICATION: Huge, with very long legs and long, narrow neck. Plumage mainly pale bluish-grey, but most breeding birds acquire rustybrown back from staining with (ferruginous and muddy) bog water during incubation. Head and upper neck black and white; bare skin of hindcrown red (size of red varying). Elongated tertials extremely bulky and disorderly, giving impression of almost Ostrich-like, bushy ‘tail’. Flight-feathers greyblack, contrastingly darker than coverts and body. Sexes similar, but male on average slightly larger when pair seen together. When duetting (neck erect, bill pointing up, tertials and breast-feathers fluffed up), wings of male halfopen, of female not. Wings long and rectangular, tips deeply ‘fingered’. Majestic flight with slow wingbeats and rather flat wings, neck and legs outstretched as on a stork (though White Stork has proportionately slightly shorter legs and neck, at least the shorter legs often discernible in flight; Grey Heron differs in having neck withdrawn, wings deeply arched on downstroke, wing-tips not deeply ‘fingered’). Expert in soaring flight but will also use active flight on migration, then forming V-shaped flocks or oblique line, flight altitude often supremely high, speed moderate. Gait measured and stately, but can be quite quick when chasing a fox away from young (performed confidently!). - Juvenile: Immediately distinguished by rather pale rufous-brown head and upper neck, lacking the black, white and red pattern of adult, and by less bulky tertials.
VOICE: Vocal, calls loud and far-carrying. Contact-call (mainly in flight) deep, resounding, trilling or jarring ‘krro’ and ‘karr’. Young in autumn have peculiar piping ‘cheerp’, mixing with deep adult calls. Pair sounds the reveille (duet-call) at breeding site in early dawn (or during light summer nights in N), male uttering loud trumpeting ‘krrroo’ and female (immediately after) lower-pitched ‘kraw’ and sometimes also hard, knocking ‘ka-ka-ka’. Other duets may run ‘krruu-ih kraw, krru-kraw, …’.