Weather likely affects the timing and rate of migration by waterfowl to their breeding grounds. I hypothesized that timing of migration by lesser scaup during spring is affected by annual variation in temperature, precipitation and ice cover. I used satellite telemetry data, waterfowl survey data and corresponding weather data to evaluate competing models that explained variation in timing and rate of migration by lesser scaup. Timing of spring migration occurred earlier and faster when lesser scaup encountered warmer temperatures and greater precipitation, both of which are known to influence thermoregulation and habitat availability for waterfowl. Migration chronology of lesser scaup and mallards differed suggesting surveys designed for mallard migration may be biased for scaup. My thesis provides insight into how environmental factors and annual variation in weather influences scaup migration chronology, and could be used to potentially improve survey techniques and breeding population estimates for lesser scaup