Acoustic Detections of Uncommon Avian Migrants

Abstract

During migration, many bird species emit nocturnal flight calls that can be passively recorded, allowing great insight into avian migration ecology. Since 2012, we have used acoustic recorders to look at the composition, timing, and factors influencing avian migration in the Bitterroot Valley of western Montana. Hidden amongst the thousands of expected detections, we found evidence of many unusual or unexpected species. These species include: Barn Owl, LeConte’s Sparrow, Canada Warbler, Chestnut-sided Warbler, Grey-cheeked Thrush, Upland Sandpiper, Pectoral Sandpiper, and Greater Yellowlegs. We reviewed observations from eBird, the Montana Natural Heritage Program, and published range maps to provide context for the rarity of detections. Our results suggest that acoustic monitoring may broaden the known distribution of migratory species in ways more traditional methods have not.