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Abstract

Greater sage-grouse (Centrocercus urophasianus; sage-grouse) is a sagebrushobligate species that has experienced species-wide declines in population density and distribution. Sage-grouse habitats support human-related needs including domestic livestock grazing, urban development, and energy extraction. The U.S. Fish and Wildlife Service identified energy extraction as a range-wide sage-grouse conservation threat. Mining has been of specific concern because of observed sage-grouse population declines and impaired habitat within close proximity to the activity. Mining may be particularly problematic for small, isolated sage-grouse populations. In southwestern Utah, proactive habitat improvements and predator management have been implemented to mitigate the potential effects of surface mining on the southernmost population of sage-grouse in the United States. We evaluated sage-grouse lek attendance trends before (1991–2010) and during (2011–2016) mining on a lek located near the mine (Sink Valley lek) to assess population responses to coal mining and related mitigation activities. Changes in lek trends have been demonstrated as a valid metric to assess the effects of conservation actions on sage-grouse populations. We used a paired t-test to compare differences in male lek attendance before and during mining and analysis of variance to determine if sage-grouse densities and distance to mining changed during the mining period. We recorded bird coordinate location and the number of birds observed at each sighting location along 10 transects within the study site area. Differences in location from mining was tested using Analysis of Variance with α < 0.5. There was no difference in the number of males attending the Sink Valley lek before and during mining. Population cycles were consistent over the time period sampled. With the exception of 2013, which had an unusually high number of sage-grouse found within the Sink Valley area, there were no differences in the number of birds observed at each sighting location in relation to the mine center (P = 0.37), the coal crushing facility (P = 0.34), and the mine boundary (P = 0.24). Coupled with ongoing mitigation activities including habitat restoration, pinyon-juniper (Pinus edulis, Juniperus osteosperma) removal, aggressive predator control, pre-mining acclimation to human influences, and removal of pinyon-juniper woodlands, surface coal mining had no negative effect on population cycles in the Alton/Sink Valley area.

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