Shorebird Staging and Migratory Movements at Chaplin and Reed Lakes, Saskatchewan, with Implications for Wind Energy Development
Increasing knowledge of long distance shorebird (order Charadriiformes) migrations may elucidate causes of shorebird declines and direct management within migratory routes. Migrating birds rely on staging sites, areas with reliably high food abundance, for rest and refueling. Stressors at these sites could have population level impacts and post-migration carry-over effects. My thesis research examined staging bird abundance and migratory movements to and from Chaplin and Reed Lakes, Saskatchewan, a major staging site of hemispheric importance in the Central Flyway used by over 100,000 shorebirds each year. My objectives were to 1) examine time of peak abundance by multiple migratory shorebird species using Chaplin and Reed Lakes during spring and fall migration, as well as estimate spring stopover duration and population size of Sanderling (Calidris alba) and 2) investigate movement patterns of migratory shorebirds as they arrive at and depart from Chaplin and Reed Lakes, and determine the extrinsic factors influencing observed flight patterns to inform risk from current and future wind energy developments. I used a combination of point count surveys and radio telemetry data to meet my objectives. Staging, arctic-breeding species at Chaplin and Reed Lakes were counted weekly during spring northward (2014 – 2017) and fall southward (2016 – 2017) migration by conducting point count surveys to examine temporal patterns and estimate population size. Detailed assessments of my focal species, Sanderling included capture, banding and radio-tagging in the Gulf of Mexico and at Chaplin Lake (2015-2017) to track their migratory movements and stopover duration in relation to weather and time of day variables using automated radio telemetry. Spring migration involved larger numbers of species (including species at risk), larger numbers of individuals, and more concentrated timing among years than fall migration. Sanderlings staged for a mean of 11.1 (95% CI = 8.59 –13.6) days and population size averaged ~75,000 birds, with estimates ranging from ~56,000 to ~91,000 among years. Population estimates were seven to 17 times larger than raw peak abundance counts, demonstrating the need to account for stopover duration in population estimates. Chaplin and Reed Lakes departures, but not arrivals, were significantly influenced by time and weather. Sanderlings were more likely to depart at sunset or sunrise when winds were blowing towards the northwest at intermediate speeds and less likely to depart when winds were blowing towards the southeast at high speeds. Knowledge of when large numbers of birds are using the area and what environmental conditions are associated with migratory movements can be used to identify where and when birds are at the greatest risks of collision with wind energy turbines. My results have implications for shorebird conservation at Chaplin and Reed Lakes and other staging sites in the Central flyway, and my thesis provides recommendations for management and mitigation of threats from current and future wind energy developments.
shorebird migration, migration chronology, staging population estimation, stopover duration, Central Flyway, migratory movements, flight orientation, wind energy development
Master of Science (M.Sc.)