Title: Greater sage-grouse face
tradeoffs between predation risk and thermal exposure in selecting
habitat
Authors: Aidan T. Beers1, 2, S. Nicki
Frey1
Author affiliations: 1Department of Wildland
Resources, Utah State University, Logan, UT USA
2Present affiliation: Department of Ecology, Montana
State University, Bozeman, MT USA
ABSTRACT
Climate change is likely to drive widespread species range shifts and
extirpations, mostly on the warm distribution edges, where habitat tends
to be fragmented, of lower quality, support lower population density,
and at greater risk from extreme weather events. In the Intermountain
West, future climate will likely be warmer and drier, driving a
reduction in sagebrush (Artemesia sp. ) and other shrubland cover.
Among the species threatened by more xeric climate is the Greater
sage-grouse (Centrocercus urophasianus ), which depends on
sagebrush for forage and shelter, though their response to temperature
is not well studied. We deployed 75 data loggers across two valleys in
southern Utah and Nevada, near the southern edge of sage-grouse
distribution, and collected temperature data for 27 months. We used
random forest models to test the impacts of temperature, land cover, and
topography on sage-grouse habitat selection and found that temperature
influenced selection in all seasons and both sites. In Utah, the warmer
site, sage-grouse selected areas near trees during the extremes of both
winter and summer. In autumn and spring those extremes were rarer and
sage-grouse avoided habitat near trees. Conversely, sage-grouse in the
cooler Nevada site selected contiguous patches of sagebrush in extremes
periods but only selected habitat near trees during winter cold,
avoiding trees during summer. Our findings show that extreme
temperatures drive sage-grouse to select habitat near trees despite the
risk likely posed by avian predators. The difference between the Utah
and Nevada sites suggests that sage-grouse prefer sagebrush as thermal
shelter but that it may be inadequate during the hottest times, forcing
riskier selection. These models point toward a more mechanistic
understanding of how sage-grouse distribution may retract at its warm
edges. This will refine our understanding of seasonal habitat
requirements and inform management decisions to prioritize thermal
refugia for an imperiled species.
KEYWORDS: greater sage-grouse, habitat selection, thermal ecology, Basin
and Range, random forest, range margins, Centrocercus
urophasianus
COVER LETTER:
Allen Moore, Andrew Beckerman, Chris Foote, Gareth Jenkins, Marcus
Lashley, and Zhaoxue Ma
Editors-in-chief