Resource selection of apex raptors: implications for siting energy development in sagebrush and prairie ecosystems

Abstract

There is an urgent need to understand ecological responses of avian species to the rapidly expanding human footprint of conventional and renewable energy development in sagebrush and prairie ecosystems. The ferruginous hawk (Buteo regalis) and golden eagle (Aquila chrysaetos) are two sympatric raptors of conservation concern that occupy and flourish in the most intact sagebrush steppe region remaining in North America. To understand these species’ use of habitat relative to energy development, we built resource selection functions using a spatially representative sample of occupied nesting territories collected in 2010–2011 and remotely sensed environmental variables across an extensive study area (186,693 km2). We used the resulting predicted resource selection maps to evaluate spatial overlap between the nesting habitats of these sympatric raptor species, as well as overlap of predicted habitat with potential development of oil/gas and wind energy resources. Remotely sensed variables were very effective in modeling patterns of nest‐site selection based on fivefold cross‐validation (>0.93 Spearman‐rank correlation) and validation with an independent dataset of historical nests collected from 2000 to 2009. Topographic roughness and intermediate levels of spring precipitation were the strongest drivers of differences in habitat use between ferruginous hawks and golden eagles. We did not detect a strong signal of avoidance of energy infrastructure by either species at current levels of development and both nested closer than expected to gravel/dirt roads associated with oil and gas infrastructure. However, extensive overlap of nesting habitat more selected by ferruginous hawks and golden eagles with areas of actual and potential energy development suggests both species are at risk from future habitat fragmentation. Given that 80% of nests are> 1 km from oil/gas wells, we believe the density of energy‐related disturbance present during our study was insufficient to drive patterns of resource selection for ferruginous hawks when considered at broad spatial scales. However, it was beyond the scope of our study to predict long‐term, population‐level responses. We suggest rigorous monitoring of long‐term trends in occupancy, productivity, and distribution is warranted for populations of ferruginous hawk and golden eagle in sagebrush and prairie ecosystems exposed to increased energy development.

Interpreting long‐distance movements of non‐migratory golden eagles: Prospecting and nomadism?

“…Golden eagles ( Aquila chrysaetos ) are long‐lived raptors with a Holarctic distribution (Watson, 2010) that have been telemetered and tracked in large numbers (Brown et al, 2017). As such, home ranges (Braham et al, 2015; Miller et al, 2017; Watson et al, 2014), habitat selection (Domenech et al, 2015; Duerr, Braham, et al, 2019; Miller et al, 2014; Squires et al, 2020; Watson et al, 2014), and migration patterns (Bedrosian et al, 2018; Duerr et al, 2012; Eisaguirre et al, 2019; Miller et al, 2016) of golden eagles have been well studied. Because of these extensive studies, seasonal movements of golden eagles are well known and are extremely diverse.…”

Key habitats and breeding zones of threatened golden eagles in Eastern North America identified by multi-level habitat selection study

“…The golden eagle is a highly mobile top predator (Katzner et al 2020) and key breeding habitats have been identi ed in some well-studied populations (Marzluff et al 1997;Singh et al 2016;Tikkanen et al 2018; Squires et al 2020). Depending on the behaviour, selection by an animal may vary.…”

“…For instance, golden eagles often establish their nests near a waterbody or stream (Menkens and Anderson 1987;Weber 2015), but water appears to be avoided while foraging (Singh et al 2016). Low vegetation cover has been identi ed as a preferred foraging habitat for golden eagles (Marzluff et al 1997;Singh et al 2016;Squires et al 2020), but high forest cover is crucial in tree nesting population or individuals (Katzner et al 2020).…”

“…However, at both the nest and foraging levels of selection, high elevation cliffs are preferred because they provide better shelters from predators and weather conditions (Tack and Fedy 2015; Weber 2015; Squires et al 2020) and updrafts to reduce energetic costs of ight (Bohrer et al 2012; Katzner et al 2012;Duerr et al 2019b). Certain land cover features (e.g.…”

“…Because high quality features facilitating ight should bene t several levels of selection, we hypothesized that aerial and topographical features (i.e., relative elevation, terrain ruggedness, northness, eastness, and wind speed) would be more important for eagle habitat selection than land cover features (i.e., forest cover and distance to water) across levels. Because aerial and topographical features were identi ed as a key aspect for both nesting and foraging (Singh et al 2016;Squires et al 2020), we predicted that eagles would show stronger selection for aerial and topographical features than for land cover features. Given the 14 -wide latitudinal range of our study area, we also hypothesized that selection for each level and for all levels combined would differ between bioclimatic zones (i.e., polar vs. boreal).…”