Julia Put 🦇🐦🐿️🐻

ALT Conservation of migratory species depends on an understanding of the drivers causing population declines across the annual cycle. Since it is difficult to track the entire annual cycle for long-distance migrants, measurements from part of the cycle may provide insights into overall drivers. Barn Swallows (Hirundo rustica) in Canada have undergone steep and long-term population declines. Using Breeding Bird Survey data and breeding performance data collected at field sites in three regions across Canada, we examined long- and short-term Barn Swallow population trends in Canada, differences in breeding performance across regions, if average breeding performance measures or colony size predicted regional population growth rates and if local breeding performance is driven by density dependence and/or recruitment. We found that long-term negative population trends were generally stronger in the east and west, and weaker in central Canada. Short-term population trends were generally weakly n