Landscape drivers of scaled quail occurrence across a broad spatiotemporal scale: implications for habitat management

Abstract Scaled quail ( Callipepla squamata ) are among the species impacted by the conservation crisis facing North American grassland birds. Habitat loss is a major threat to grassland birds and may be a driver of scaled quail declines, particularly at large spatial scales. Our primary objective was to inform scaled quail management at the ecoregion scale by identifying specific habitat factors that may constrain scaled quail occurrence. To accomplish this, we related spatially and temporally explicit scaled quail occurrence records with corresponding remotely sensed land cover and land use data across the range of scaled quail in Texas, USA, which includes the Edwards Plateau, High Plains, Rolling Plains, South Texas Plains, and Trans‐Pecos ecoregions. The dataset included 20,852 records spanning the study area from 1986 to 2019. We fit species‐habitat association models to these data using generalized linear mixed‐effects models with a binomial response distribution. We also fit generalized additive mixed‐effects models in a time series framework to place management inferences in the context of a changing environment. Factors that potentially constrained scaled quail occurrence varied by ecoregion and were largely consistent with ecoregional distinctions in prevailing landscape trends and processes. The species‐habitat association models indicated that scaled quail occurrence may be constrained by the following ecoregion‐specific habitat factors: insufficient annual herbaceous cover and excessive tree cover in the Edwards Plateau; insufficient shrub cover and evenness of land cover types, and excessive croplands in the High Plains; insufficient bare ground, annual herbaceous cover, perennial herbaceous cover, and evenness of land cover types, and excessive shrub cover, tree cover, and croplands in the Rolling Plains; insufficient evenness of land cover types, and excessive bare ground, annual herbaceous cover, perennial herbaceous cover, tree cover, croplands, and developed land in the South Texas Plains; and insufficient shrub cover and annual herbaceous cover in the Trans‐Pecos. Given these results, scaled quail management at the ecoregion scale may be enhanced by promoting practices such as prescribed fire or herbicide treatments to reduce tree cover in the Edwards Plateau, Rolling Plains, and South Texas Plains, converting croplands to grasslands or adding prairie buffers around row crops in the High Plains, Rolling Plains, and South Texas Plains, controlling perennial herbaceous cover in the South Texas Plains, modifying grazing practices to increase the evenness of land cover types in the Rolling Plains and South Texas Plains, and maintaining current practices that promote shrub cover and annual herbaceous cover in the Trans‐Pecos. These results constitute a baseline for scaled quail habitat management at the ecoregion scale that may be key to addressing declines.