Habitat selection and nesting ecology of translocated Greater Sage-grouse

Abstract

Sagebrush ecosystems are one of the most imperiled ecosystems in North America. The cumulative effects of habitat loss, fragmentation and degradation of the sagebrush ecosystem threaten the persistence of the Greater Sage-grouse. Sage-grouse depend on healthy, intact areas of sagebrush habitat throughout the year. In Alberta, the sage-grouse population is estimated to be only 5% of what it was in 1968. During the spring of 2011 and 2012, 41 sage-grouse were fitted with GPS transmitters and translocated from stable populations in Montana to active lek sites in southeast Alberta. I conducted research to improve our understanding of translocation as a management tool, and how translocated sage-grouse are affected by anthropogenic features. I examined nesting ecology including the differences in post-release movements between nesting and non-nesting hens and the extent to which nest success is affected by anthropogenic features. I also identified habitat that translocated sage-grouse select in relation to anthropogenic and natural features. My research documented some of the largest post-release movement distances, rates and areas ever recorded for grouse after being translocated. Average weekly linear distance travelled was 56 km and average area traversed was 1944 km2. Non-nesting hens had significantly higher movement rates than nesting hens. Movement rates of nesting hens decreased during the nest initiation period, whereas movement rates of non-nesting hens did not decrease until 6 weeks later. Apparent annual hen survival ranged between 31-72% across the study period. Nest initiation (53%) and nest success (29%) were low compared to other sage-grouse populations across their range. Nest success decreased with increasing distance from trees, power lines and settlements, suggesting that translocated hens are naïve to the release area and do not recognize the risks that are typically associated with certain anthropogenic features. Translocated sage-grouse were more likely to be observed, with increasing distance from all of the anthropogenic features included in the movement models: as far as 3 km from trees and gas wells, 10 km from buildings and 15 km from settlements, at least 23 km from power lines and 2.5 km from roads. Interaction models suggest that sage-grouse are avoiding anthropogenic features because of the disturbance of the features themselves, and not because the features occur in poor sagebrush habitat. My results indicate that the effects of power lines, buildings, trees and oil wells (up to 5 km) on the occurrence of sage-grouse were largest, suggesting that these features should be prioritized for removal. However, it is likely that cumulative effects of some or all anthropogenic features cause sage-grouse to select habitat further away from these features. The predicted intensity map I generated could be used to help strategically guide habitat enhancement efforts in the study area. Habitat enhancements would best be focused in areas where predicted intensity was high and suitable habitat was present yet no sage-grouse were observed, with the goal of increasing the likelihood of sage-grouse use within those areas. Future assessments of proposed developments should consider the construction of all new anthropogenic features as a potential detriment to habitat quality.