Predicted 2020 densities for 11 songbird species across the western United States

Informed wildlife management requires robust information regarding population status, habitat requirements, and likely responses to changing resource conditions. Growing evidence indicates single species management may inadequately conserve communities and result in undesired effects to non-target species. Thus, management can benefit from habitat relationship information for multiple species within, and across, ecosystems. Using 13 years of point count data (2008-2020) collected across the western United States and a suite of relevant covariates for habitat, we fit hierarchical models to characterize and predict songbird densities and evaluate population trends for 11 species of interest: Bewick’s Wren (Thryomanes bewickii; BEWR), Brewer’s Sparrow (Spizella breweri; BRSP), Black-throated Gray Warblers (Setophaga nigrescens; BTYW), Gray Flycatcher (Empidonax wrightii; GRFL), Gray Vireo (Vireo vicinior; GRVI), Green-tailed Towhee (Pipilo chlorurus; GTTO), Juniper Titmouse (Baeolophus ridgwayi; JUTI), Loggerhead Shrike (Lanius ludovicianus; LOSH), Sagebrush Sparrow (Amphispiza belli; SABS), Sage Thrasher (Oreoscoptes montanus; SATH), and Townsend’s Solitaire (Myadestes townsendi; TOSO). The resulting maps include density (birds/km2) for each species (BEWR_2020_PredictedDensity.tif, BRSP_2020_PredictedDensity.tif, BTYW_2020_PredictedDensity.tif, GRFL_2020_PredictedDensity.tif, GRVI_2020_PredictedDensity.tif, GTTO_2020_PredictedDensity.tif, JUTI_2020_PredictedDensity.tif, LOSH_2020_PredictedDensity.tif, SABS_2020_PredictedDensity.tif, SATH_2020_PredictedDensity.tif, and TOSO_2020_PredictedDensity.tif), given 2020 environmental conditions, as well as masks representing all raster cells where one or more covariate pixel value(s) fell outside of the 2.5 and 97.5 percent quantiles of the covariate sample used when fitting the model (BEWR_mask_raster_2020.tif, BRSP_mask_raster_2020.tif, BTYW_mask_raster_2020.tif, GRFL_mask_raster_2020.tif, GRVI_mask_raster_2020.tif, GTTO_mask_raster_2020.tif, JUTI_mask_raster_2020.tif, LOSH_mask_raster_2020.tif, SABS_mask_raster_2020.tif, SATH_mask_raster_2020.tif, and TOSO_mask_raster_2020.tif). Values of one within the mask layers indicate there may be considerable uncertainty associated with the predicted values and/or that values may be unusually high or low.