a1 Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK SyN 5E2, Canada (Current address: Powder River Eagle Studies, P.O. Box 2411, Gillette, Wyoming, 82727, U.S.A.). E-mail: email@example.com
a2 Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, SK SyN 5E2, Canada Current Address: Centre for Studies in Agriculture, Law and the Environment, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK SyN 5A8, Canada)
We examined population and ecosystem patterns hoping to inform conservation strategies for Burrowing Owls Speotyto cunicularia in Canada. The owls chose moderately to heavily grazed grasslands for nesting and roosting, and avoided cultivated fields. Where grassland patches were isolated in 90% cultivation, owls dispersed later, for shorter distances and less often. Mortality rate during the 5-month study was high (adult ratio 0.45, juveniles 0.55), which may contribute to local declines. Additional mortality may occur on migration and during winter. We extrapolate from local effects (loss of grassland habitat with burrows for roosting, and ~2% “incidental” predation) to suggest that such changes detrimental to the owls occur throughout the central Great Plains ecosystem which the owls occupy year-round. The changes include ecosystem processes such as plant succession, owl dispersal and predation. These changes are likely to be irreversible on a scale that would be required to help this owl. The species may face extinction in Canada, at the northern limit of its range.