Lesser Black-backed Gull

Status Rare winter visitant. The first record for Nova Scotia was a third-winter bird photographed in Digby by Davis Finch on 25 March 1970. Up to the time of writing (January 1986), this bird has returned to Digby every autumn since (earliest arrival 19 September 1976); two adults were seen there on 4 April 1980. In January 1979 a first year and a third-year bird were reported in the Dartmouth-Halifax area, and the older bird has returned to the same site annually since. Another bird appearing first in winter 1981-82 has also become a regular visitant to the Halifax waterfront. A Lesser Black backed Gull was seen over Sable Island on 6 September 1979 and in June 1981 a third year bird was found lingering on Cape Breton Island (R. Stymeist). In 1982, single adults were observed: at Petit de Grat, Richmond County, on 13 March; at Port Philip, Cumberland County, on 18 April; on 17 September at Bon Portage Island. The species colonized Iceland in the 1920s, and there can be little doubt that our birds are the forerunners of a further westward expansion in range.

Remarks Adults resemble miniature Great Black-backed Gulls but are smaller than a Herring Gull, have a more delicate bill and their legs are yellow, not flesh-coloured. First-winter birds are darker than those of the other two species. They may be distinguished from young Herring Gulls by their darker wing coverts, which form a broader dark margin on the trailing edge of the wings in flight.

This gull breeds in northern Europe and Iceland and normally winters from Europe to southern Africa. Wanderers are regularly recorded in eastern North America from Labrador to Florida, and it is likely that some breed here, perhaps mated to Herring Gulls if they cannot find others of their own kind.

The ancestors of the Lesser Black-backed and Herring Gulls probably inhabited the North Pacific and spread into Eurasia and North America at the end of the Ice Age. The backs of the Eurasian populations become progressively darker as one travels west, culminating in the Lesser Black-backed. The backs of the Herring Gulls of North America remain pale, and that species has crossed the Atlantic to establish a breeding range which overlaps with that of the Lesser Black-backed Gull. The two forms are distinct and normally do not interbreed, yet they are part of a circumpolar ring of intergrading and interbreeding subspecies.