Birds in Bulgaria

L 52-58 cm, WS 120-140 cm. Habits similar to Herring Gull, to which it is closely related (sometimes treated as conspecific, but may be even closer to Lesser Black-backed Gull). Sedentary. Increasing in many areas, and now frequently straggles in Jul-Oct to NW, NC Europe and Baltic.
IDENTIFICATION: Four age-groups (see p. 168). Very similar to Herring Gull in adult and subadult plumage. Immatures more like Lesser Blackbacked. Consistently adults have whiter head in autumn (no or very little streaking) and bright yellow legs all year, and often show all or many of following characteristics (referring to ssp. michahellis of W France, SW Iberia, Mediterranean and SW Black Sea) compared with Herring Gull: in flight slightly longer wings; on adults, outer primaries have more black and smaller white spots; larger red spot on bill; red or orange orbital ring; on average slightly darker grey back with less bluish cast; more nasal calls; immatures have neater tail-band and paler rump, somewhat darker inner primaries (recalling Lesser Black-backed), lighter head and underparts and on average a darker bill. - Variation: Birds of Atlantic Islands (atlantis) are rather dark grey on back. Adults of N Black Sea and Caspian Sea (cachinnans; possibly full species) very like michahellis but slightly paler grey above, with on average less black on wing-tip but larger white spots, and have more dark marks on head/nape in winter (thus closer to Herring Gull), but are slimmer and longer-winged and longer-legged, and bill is long and lacking strong gonydeal angle; immatures told by shape and often by on average paler underwing and by plainer dark bases to upper greater coverts (wing-bar effect), but differences subtle and a cautious approach advisable. Breeders in E Turkey and Armenia (armenicus; possibly full species) are small and slim and usually have darkish eye, dark-banded bill-tip, and a comparatively short bill.
VOICE: All calls more similar to Lesser Black-backed Gull’s than Herring’s owing to the nasal, rather deep voice.