Population trends of gulls and Arctic terns nesting in the Belcher Islands, Nunavut

Little information exists on the population trends of gulls and terns nesti ng in the Arctic. In 1997, we surveyed the number of glaucous gull (Larus h yperboreus), herring gull (Larus argentatus), and arctic tern (Sterna parad isaea) nests on the Belcher Islands (56 degrees 00'-57 degrees 30'N, 79 deg rees 30'- 80 degrees 00'W). We compared our results with the mean number of nests per island counted in the Belcher Islands in the late 1980s using th e same survey methods.:The mean number of gull nests per island had decline d in all five archipelagos surveyed, and the decline was significant in thr ee regions. The number of arctic tem nests had also declined in all three r egions where they were originally present, although this decline was signif icant in only one region. The causes of these apparent declines are unknown . Adult mortality or emigration of gulls from the area may have occurred in response to changes in polynya formation during recent winters, which rest ricted access to marine food sources. Reproductive success of gulls may als o be low in response to the recent 75% decline in common eiders nesting in the Belcher Islands. Elder eggs and ducklings are an important food source for gulls during the breeding season. The decline of nesting arctic terns m ay reflect either winter mortality of tern populations caused by unknown fa ctors or emigration out of the Belcher Islands in response to regional eggi ng and disturbance by local residents.