SIGHT OBSERVATIONS OF IVORY GULLS ON PRINCE EDWARD ISLAND

by Martin K. McNicholl, 320 Markham St., Tbronto, Ontario M6G 2K9

At 15:30 on 16 April 1977, I was birdwatching in Prince Edward Island National Park, P.E.I., when I noticed a small flock of gulls roosting beside a small pond behind sand dunes. The flock included 18 Great Blackbacks, 12 Herring, 2 Iceland, 2 Ring-billeds, and one smaller, entirely white gull with black legs and yellow—tipped black bill which could only be an Ivory. This bird was clearly smaller than the Ring-billeds beside it, and thus smaller than any other primarily white gull, and the other features noted are diagnostic (see Peterson 1980). When all the gulls rose in flight, the Ivory Gull also flew more tern-like than the others. At 14:20 on 24 April, I was at the cormorant colony at Cape Tryon with Lawrence Gray, when a bird with the same field marks flew by at less than 10 m from us. we observed the same field marks, and noted that the’gull was slightly larger than the Rock Doves that nest there. As we did not obtain photographic evidence, these two records must remain hypothetical, but the distinctive field marks make our sightings highly probable.

Godfrey (1954) listed the Ivory Gull as hypothetical in Prince Edward Island, a status retained in the latest provincial check-list (Anonymous 1978). However, Godfrey (1954) notes that even this status is based on vague reports without well substantiated details. Thus, our records at least increase the probability that this species does occur on the island.

Ivory Gulls occur regularly in winter along Labrador and Newfoundland, some- times in large numbers (Bent 1921; Finch 1975, 1976a,c; Fbrster 1983; Godfrey 1966; Vickery 1977a,b, 1978, 1979a,b, 1981a,b, 1982), and have been seen off Labrador even in summer (Brown 1976). They occasionally turn up on Christmas Bird counts in various sites in the Maritimes (Table 1), and sometimes stray to New Brunswick (Bent 1921; Finch 1976a; Godfrey 1966; Squires 1976), Nova Scotia (Bagg and Emery 1964; Finch 1970,1976b; Godfrey 1966; Neil 1983; Tufts 1973; Vickery 1978, 1979a), and the northern coast of the Gulf of St. Lawrence (Bent 1921; Godfrey 1966; Lewis 1941; Taverner 1940; Tanguay 1949). These records suggest that it is a rare, but expected winter visitor throughout the Maritimes.

Our two observations, the number of sightings of Ivory Gulls elsewhere in the Maritimes, and the recent report of a Lesser Black-backed Gull on Prince Edward Island (Hogan 1983) all suggest that observers on the island should keep a careful lookout for unusual gulls there.

Acknowledgements The two Ivory Gull sightings reported in this note took place while I was assisting

Geoffrey G. Hogan in cormorant studies for his M.Sc. thesis at Brock University, St. Cbtharines, Ont. under Ralph D. Mbrris.

Literature Cited Anonymous. 1978. Prince Edward Island field check- list of birds, 2nd edition. P.E.I. Dept. of Tourism, Parks and Conservation, Charlottetown. Bagg, A.M. and R.P. Emery. 1964. Winter season. Dec. 1, 1963—Mar. 31, 1964. Audubon Field Notes 18:334-340. Bent, A.C. 1921. Life histories of North American gulls and terns. U.S. Natl. Mus. Bull. 113 (reprinted by Dover, 1963).

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