Movements of Pre-migratory Surf and White-winged Scoters in Response to Pacific Herring Spawn

Abstract

Abstract We documented the movement and distribution patterns of wintering Surf Scoters (Melanitta perspicillata) and White-winged Scoters (Melanitta fusca) in relation to herring spawn events in the Strait of Georgia, British Columbia. Radio-telemetry and surveys were conducted in Baynes Sound, an important wintering area where scoters feed primarily on clams. In early March, herring spawn events in areas adjacent to Baynes Sound provide a short-term pulse of abundant and easily accessible food, which could affect habitat use by wintering scoters from Baynes Sound. Radio-marked Surf Scoters and White-winged Scoters exhibited limited movements during winter, in contrast to the spring herring spawn season, when both scoter species moved greater distances to access herring eggs. Most individuals were located near spawning locations at least once during the spawning season, and the majority of telemetry locations were close to spawning sites, with Surf Scoters showing a higher association with spawn for both...