Birds in Bulgaria

small lakes with sheltering vegetation, on damp bogs and in marshes, typically in remote areas in far north, but has spread south recently (linked with less shy, more confiding habits). Migrates to open waters in NW Europe. Hardy, closely following retreat of ice in spring.
IDENTIFICATION: Huge. Plumage white, but many in spring and summer have head and neck stained brown (rarely seen in Mute). Neck long, upper part generally held straight when swimming. Best told from Mute and Bewick’s by long, wedge-shaped bill, largely yellow with black tip, yellow forming pointed wedge, reaching in front of nostril. - Juvenile: Grey (tinged brownish), clearly less brown and slightly paler than juvenile Mute; very similar to juvenile Bewick’s but (in British Isles) often slightly paler. Bill pattern of adult discernible (black of adult is pink, yellow is off-white).
VOICE: Highly vocal. Calls loud and bugling in quality, similar to those of Bewick’s Swan but usually louder, slightly lower-pitched on average, notes more straight, not with such a marked diphthong, and notes often given in groups of three or four, ‘kloo-kloo-kloo’, instead of one or two as most often in Bewick’s. Insignificant, slight hissing sound from wingbeats, unlike musical throb of Mute.