Least Flycatchers (Empidonax minimus), like most aerial insectivores, have declined rapidly over the last 50 years in North America, mostly due to the extensive use of insecticides. Since the Least Flycatcher is the most common bird encountered in the Beaverhill Natural Area, located in central Alberta, Canada, likely due to high insect densities, we studied the nesting success and habitat use of this species in the summer of 2022. We monitored 28 nests until fledging and found a high nest success rate and more nesting in trembling aspen trees (Populus tremuloides), compared to balsam poplar trees (Populus balsamifera). We found that mean host tree height was greater for successful nests than unsuccessful nests. In addition, based on a breeding bird census, we found a high breeding density in our research area. Understanding the relationship between breeding success and habitat is important for conservation actions to be effective in the future. Our results show that the Beaverhill Natural Area has high-quality habitat for Least Flycatchers and is a candidate for critical habitat when designated under the Canadian Species at Risk Act.

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