Thayer's Gulls Wintering off Western Newfoundland

Abstract

Observations were made in the course of cruise 181 of the Fisheries Research Board trawler 'A.T. Cameron', along the southern and western Newfoundland coasts. The commonest Larus gulls on this cruise were Iceland Gulls, L. glaucoides, (mainly L.g.kumlieni, but with a few L.g.glaucoides), followed by Great Black-backed Gulls, L. marinus; Herring and Glaucous Gulls, L. hyperboreus, were scarce. When the ship was moored at Woody Point harbour (49 degree 30'N 57 degree 55W), Bonne Bay, close views were had of at least 2 Thayer's Gulls. These birds had the appearance of adult herring Gulls, but with dark brown, not black wing-tips: the brown area was about as large as the black area in the Herring Gull, and there was no possibility of confusing it with the small dark areas at the wing-tips of L.g. kumlieni. Another Thayer's Gull was seen on February 3; this was attracted to offal when the ship was stationary in slob ice at 49 degree 10'N 59 degree 48'W. Probable sightings were had from the moving ship on February 5, of single birds at 47 degree 35'N 59 degree 25'W and 47 degree 32'N 59 degree 11'W, south west of Port-aux-Basques. On the same date, approximately 25 Herring Gull-type birds were estimated among the thousands of gulls around the fish plant in Rose Blanche harbour (47 degree 36'N 58 degree 42'W); some of these were certainly Thayer's Gulls, but counts were not possible. It seems likely that a small part of the Thayer's Gull population - perhaps that breeding at the eastern edge of its range -- winters on the Atlantic and not the Pacific coast.