Population trends and interactions among terns and gulls in Gros Morne National Park, Newfoundland

Abstract

Although populations of Common Terns and Arctic Terns (Sterna hirundo, S. paradisaea) have been decreasing and gull (Larus spp.) populations have been increasing in eastern North America for more than 50 years, little is known about the population trends of these species in Newfoundland. Here we present data, spanning two decades, on the population trends and interactions of terns and gulls on five islands in Gros Morne National Park in western Newfoundland. Tern populations in this region are increasing despite interactions with gulls and low productivity. Immigration from disturbed colonies elsewhere is suggested as a possible source of the increase. Gull populations have also increased substantially since the early 1970s and closely follow local production of fisheries offal, as indicated by landing trends in the area. Implications for gull management strategies are discussed.