Site use and migration of scoters (Melanitta spp.) in relation to the spawning of Pacific herring (Clupea pallasi)

摘要

I investigated movements and site use by two scoter species during late winter and spring. In the Strait of Georgia, British Columbia, I found that radio-transmitter-tagged pre-migratory surf scoters (Melanitta perspicillata) and white-winged scoters (Melanitta fusca) left the areas where they had spent the winter and moved to Pacific herring (Clupea pallasi) spawn sites coincident with spawn availability in March. In southeast Alaska, I identified stopover and staging sites of satellite-transmitter-tagged migrating surf scoters and identified one site, Lynn Canal, as particularly important. I found that herring spawn availability and proximity to the mainland coast were strong predictors of site use, suggesting that the resource availability and geography of southeast Alaska provide important stopover habitat for migrants. Overall, there was strong phenological correspondence between the northward progression of scoter migration and herring spawn availability, suggesting that herring spawn is a valuable resource for scoters in late winter and spring.