Bird associations with floristics and physiognomy differ across five biogeographic subregions of the Great Basin

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The plant species and functional groups that were associated significantly with occupancy varied considerably among subregions. Twenty-four percent of bird-plant associations that were significant at the Great Basin level were not significant in any subregion. Associations between occupancy and floristics differed the most between the Sierra Nevada and central or western subregions, and the least between the eastern and western subregions. Associations between occupancy and physiognomy differed the most between the Sierra Nevada and western and central subregions, and the least between the northern and western subregions. These differences and similarities may reflect variations in climate or bird communities or differences in sampling effort. In addition, the number and strength of associations between occupancy and floristic or physiognomic covariates varied substantially among bird species and subregions. We recommend that the management of birds across the Great Basin or other large ecoregions evaluate and account for geographic variation in environmental attributes associated with occupancy, and not assume bird-plant relations are consistent across the Great Basin.