Staging Little Gulls, Larus minutus, on the Niagara River, Ontario: 1987-1996

Abstract

Since its first definite sighting in Ontario in 1930, the Little Gull (Larus minutus) has become an uncommon, but increasingly regular, migrant in the Great Lakes region on its way to and from the wintering areas on the Atlantic seaboard and Mississipi River. Over a period of 10 years (1987-1996), Little Gulls and Bonaparte's Gulls (Larus philadelphia) were counted as they flew over the Niagara River, Niagara-on-the-Lake, to their nocturnal roost in Lake Ontario to document the timing of migration and to monitor gull numbers. Counts generally began in October or November (range 3 October - 21 November) and continued until the fly-past ceased for winter; counting was resumed in early spring to document spring migration return dates. Altogether, 768 Little Gulls were counted and the vast majority (64.9%) of these were in the 1994/1995 (214) and 1995/1996 (285) seasons. This was not due to variation in coverage; in 1994/1995 no counts were made in the autumn season and were made only from 13 January to 1 May (n = 11). In the seasons for which coverage was similar there was a marginally significant increase in numbers of Little Gulls counted during the spring season, whereas there was a decrease in autumn counts. A comparison of Little Gull counts made at the Niagara River with those made at other staging areas in Ontario indicated that the Niagara River and Long Point may be the most important staging areas on the continent. Recent declines at Long Point coincide with an increase on the Niagara River, suggesting that preferred feeding areas have changed.