Status assessment and conservation plan for the western burrowing owl in the United States

The Western Burrowing Owl (Athene cuniculariahypugaea) is a grassland specialist distributed throughout w. North America, primarily in open areas with short vegetation and bare ground indesert, grassland, and shrub-steppe environments.Burrowing Owls are dependent on the presenceof fossorial mammals (primarily prairie dogs andground squirrels), whose burrows are used fornesting and roosting. Burrowing Owls are protectedby the Migratory Bird Treaty Act in the United States and Mexico. They are listed as Endangered in Canada and Threatened in Mexico. They are considered by the U.S. Fish and Wildlife Service(USFWS) to be a Bird of Conservation Concern at the national level, in three USFWS regions, and innine Bird Conservation Regions . At the state level, Burrowing Owls are listed as Endangered in Minnesota, Threatened in Colorado, and as a Species of Concern in California, Montana, Oklahoma, Oregon, Utah, Washington, and Wyoming. Burrowing Owls historically bred from sc. and sw. Canada southward through the Great Plains and w. United States and south to c. Mexico. Although the historical breeding range is largely intact, range contractions have occurred primarily at peripheral regions, in s. Canada, the ne. Great Plains, and parts of California and the Pacific Northwest. BurrowingOwls winter in the sw. and sc. United States, throughout Mexico, and occasionally as far south as Panama. Populations of Burrowing Owls have declined in several large regions, notably in the ne. Great Plains and Canada. However, estimates of population trends in many regions are generally inconclusive due to small samples sizes and high data variability. Population trends as determined from North American Breeding Bird Survey (BBS) data were inconsistent, with some regions exhibiting positive trends and other regions exhibiting negative trends. When taken as a whole, the BBS indicated an area of generally declining populations in the northern half of the Great Plains, and generally increasing populations in the interior U.S. and in some southwestern deserts. The Christmas Bird Count indicated a significant population decline in California (1966-1989). Local surveys have detected declining populations and/or range reductions in California, Iowa, Kansas, Minnesota, Nebraska, New Mexico, North Dakota, Oklahoma, Oregon, South Dakota, Texas, Washington, and throughout the range of the species in Canada. Primary threats across the North American range of the Burrowing Owl are habitat loss due to land conversions for agricultural and urban development, and habitat degradation and loss due to reductions of burrowing mammal populations. The elimination of burrowing mammals through control programs and habitat loss has been identified as the primary factor responsible for declines of Burrowing Owls. Additional threats to Burrowing Owls include habitat fragmentation, predation, illegal shooting, pesticides and other contaminants. The types and significance of threats during migration and wintering are poorly understood. The preservation of native grasslands and populations of burrowing mammals is ultimately critical for the conservation of Burrowing Owls. Efforts to maintain and increase populations of burrowing mammals through reduction of lethal control programs and landowner and land manager education should be undertaken. Burning, mowing, and grazing may be employed to maintain suitable habitat structure for nesting Burrowing Owls, although additional research is needed. Efforts to reintroduce or relocate Burrowing Owls should be critically reviewed to determine efficacy and best methods. Current large-scale monitoring efforts are generally inadequate. Effective programs to better determine actual population trends and demographics of Burrowing Owl populations should be developed and implemented.