Reversing Tree Encroachment Increases Usable Space for Sage-Grouse during the Breeding Season

In the Great Basin, coniferous trees are expanding their range at a rate higher than any other time during the Holocene. Approximately 90% of the expansion has occurred in ecosystems previously dominated by sagebrush (Artemisia spp.). Transitions from open, sagebrush steppe to woodlands are considered a threat to the greater sage-grouse (Centrocercus urophasianus), a sagebrush obligate gallinaceous bird that occupies approximately 56% of its pre-European settlement distribution. Using a telemetry data set from 2010–2017 breeding seasons for a treatment area with conifer removal and an experimental control area, we assessed the efficacy of conifer removal for increasing usable space and determined relative probability of use of a landscape previously impacted by conifer expansion. Sage-grouse increasingly selected areas closer to conifer removals and were 26% more likely to use removal areas each year after removal. Sage-grouse were most likely to select areas where conifer cover had been reduced by ≤10%. The proportion of available locations having a high relative probability of use increased from 5% to 31% between 2011 and 2017 in the treatment area and locations with the lowest relative probability of use decreased from 57% to 21% over the same period. Dynamics in relative probability of use at available locations in the control area were stochastic or stable and did not demonstrate clear temporal trends relative to the treatment area. Targeted conifer removal is an effective tool for increasing usable space for sage-grouse during the breeding season and for restoring landscapes affected by conifer expansion.