Cooperative Fish and Wildlife Research Units Program: Idaho
Education, Research and Technical Assistance for Managing Our Natural Resources

The Burrowing Owl (Athene cunicularia) is federally endangered in Canada, is a species of national conservation concern in the United States, and is a Species of Greatest Conservation Need (SGCN) many western states. Abundance of Burrowing Owls has declined over the past several decades (Conway and Pardieck 2006, Sauer et al. 2014, Conway 2018), and its breeding distribution has been significantly reduced in size (Wellicome and Holroyd 2001, Macias-Duarte and Conway 2015). However, survey data suggest that breeding populations are stable in some locations whereas other populations are declining rapidly (Sauer et al. 2014). We do not know the cause of these declines (or why they vary spatially so much), and implementing effective management or policy actions to halt declines requires knowledge of the underlying cause(s) of the observed declines.
Over the past 9 years, we have attached 5-gram solar-powered satellite transmitters (PTTs) to >120 adult Burrowing Owls at >40 locations (in 12 U.S. states and 3 Canadian provinces). The goal of this large, collaborative project is to thoroughly document migratory patterns of the Burrowing Owl and to link breeding locations with wintering locations. These linkages will allow us to examine whether the breeding populations that are declining more dramatically are spending the winter in similar locations (i.e., whether the observed population declines on the breeding grounds are likely caused by problems on the wintering grounds or migratory routes) and allow us to compare survival among seasons to document the stage of their annual life cycle where the declines are manifest. Effective management and recovery efforts require knowledge of the full life-cycle movements of this migratory owl so that conservation efforts can be increased in the most pressing areas of their continental range.
To date, the project has produced novel information regarding the migratory timing, migratory routes, and wintering locations of adult Burrowing Owls throughout the U.S. and Canada. Breeding owls in Oregon and Washington wintered in the U.S. (in WA, OR, and CA) and migratory behavior differed between males and females; most female owls migrated to California for the winter whereas most male owls wintered in east-central and north-central Washington. Breeding owls in Nevada migrated southern California and Baja California in Mexico. In contrast, breeding owls in all other regions of the U.S. and Canada wintered primarily in mainland Mexico. From 2009-2015, we deployed geolocators on 296 burrowing owls at 13 locations in the U.S. and we recaptured and obtained data from 52 owls. From 2013-2022, we also deployed satellite transmitters (PTTs) on >120 adult owls in 10 U.S. states and 3 Canadian provinces; thus far, we have obtained migration data from >60 of those owls.
The work proposed here is for a second phase of this project and involves attaching satellite transmitters to juvenile burrowing owls (hatch-year owls) to document range-wide patterns in natal dispersal and first-year survival. Burrowing owls are declining precipitously in some areas (e.g., Canada, California, and eastern Washington). One proposed cause of population declines in those areas is the lack of juvenile owls to return as breeders (i.e., low local recruitment). To test that hypothesis, we plan to attach satellite transmitters to juvenile owls throughout their breeding range in western North America to document regional patterns in natal dispersal and local recruitment following their first year’s migration. This project will help determine why some populations are declining and others are not, and whether the cause of the declines are on the breeding grounds, migratory routes, or wintering grounds.