Greater sage‐grouse habitat selection varies across the marginal habitat of its lagging range margin

Abstract

Studying wildlife–habitat relationships at the edges of their range can provide valuable insights into the environmental factors limiting wildlife distributions and most likely to drive extirpations and range shifts in response to landscape change. Yet the relative impact of those factors is likely different along the range margin, so it is important to identify the limitations to suitable habitat at both regional and local scales. Some of the most drastic impacts of large‐scale landscape changes in North America have occurred and are forecasted in the sagebrush steppe ecosystems, where species unable to seek new habitat in the fragmented landscape will be vulnerable to climatic extremes, vegetation community shifts, and anthropogenic land use change. One of the species likely under major threat from landscape changes is the greater sage‐grouse (Centrocercus urophasianus), a sagebrush obligate with habitat constraints that make it susceptible to habitat loss impacts as sagebrush systems contract and fragment at their southern range margin, already naturally fragmented. In this study, we evaluated factors of topography and land cover directly impacting habitat selection by sage‐grouse in four study areas along their lagging range edge. We used >116,000 GPS locations from >90 grouse across four study areas in southern Utah and Nevada from 2014 to 2020 in habitat selection analyses using random forest models. Our results showed that sage‐grouse exploit topography and sagebrush cover, possibly to break predator sight lines and moderate the risk posed by avian predators using tree perches, complicating the effects of tree cover and conifer encroachment into sagebrush habitat. We found similar trends across all four study areas, suggesting sage‐grouse along the southern range margin face similar limitations. However, the effects were nonlinear and varied—models trained in one study area were only moderately successful at predicting selection in others. The local idiosyncrasies along this southern range margin indicate a need for place‐based conservation for sage‐grouse and other potentially imperiled species. Incorporating new understandings of local impacts will refine regional and range‐wide models and support efforts to effectively create habitat and plan for range shifts by vulnerable species in response to environmental change.

Intraspecific variation in habitat relationships for pygmy rabbits: Implications for conservation of habitat specialists

“…Similar regional variation in habitat associations has been recognized for another wide‐ranging sagebrush specialist, the Greater sage‐grouse. Doherty et al (2016) documented functional habitat responses for several environmental parameters across sage‐grouse management zones, and Beers and Frey (2022) reported regional variation in habitat selection among sage‐grouse populations in Nevada and Utah. These studies emphasize the importance of intraspecific variation in conservation planning, even for highly specialized species.…”

“…Effective conservation of habitat specialists will be advanced by incorporating an understanding of diversity in environmental relationships and adaptability to environmental variation. Indeed, a growing body of evidence supports intraspecific variation in species responses to changing environments across diverse taxa (e.g., Beers & Frey, 2022; Beever et al, 2017; Godhe & Rynearson, 2017; Herrando‐Pérez et al, 2019; Jeffress et al, 2013; Oney et al, 2013; Rapacciuolo et al, 2014); failing to integrate intraspecific variation in response to climate change could contribute to misinterpreting mechanisms influencing population persistence and misdirecting conservation efforts aimed at mitigating the consequences (Hällfors et al, 2016; Nice et al, 2019).…”