Date Published: January 12, 2017
Publisher: Public Library of Science
Author(s): Paul C. Burr, Aaron C. Robinson, Randy T. Larsen, Robert A. Newman, Susan N. Ellis-Felege, Mark S. Boyce.
Recent advancements in extraction technologies have resulted in rapid increases of gas and oil development across the United States and specifically in western North Dakota. This expansion of energy development has unknown influences on local wildlife populations and the ecological interactions within and among species. Our objectives for this study were to evaluate nest success and nest predator dynamics of sharp-tailed grouse (Tympanuchus phasianellus) in two study sites that represented areas of high and low energy development intensities in North Dakota. During the summers of 2012 and 2013, we monitored 163 grouse nests using radio telemetry. Of these, 90 nests also were monitored using miniature cameras to accurately determine nest fates and identify nest predators. We simultaneously conducted predator surveys using camera scent stations and occupancy modeling to estimate nest predator occurrence at each site. American badgers (Taxidea taxus) and striped skunks (Mephitis mephitis) were the primary nest predators, accounting for 56.7% of all video recorded nest depredations. Nests in our high intensity gas and oil area were 1.95 times more likely to succeed compared to our minimal intensity area. Camera monitored nests were 2.03 times more likely to succeed than non-camera monitored nests. Occupancy of mammalian nest predators was 6.9 times more likely in our study area of minimal gas and oil intensity compared to the high intensity area. Although only a correlative study, our results suggest energy development may alter the predator community, thereby increasing nest success for sharp-tailed grouse in areas of intense development, while adjacent areas may have increased predator occurrence and reduced nest success. Our study illustrates the potential influences of energy development on the nest predator—prey dynamics of sharp-tailed grouse in western North Dakota and the complexity of evaluating such impacts on wildlife.
The United States has been gradually reducing its reliance on imported petroleum products by significantly increasing its own production . This was primarily made possible through the advent of hydraulic fracturing in conjunction with horizontal drilling . These technological developments, amongst others, have increased the amount of recoverable oil within formations and has made commercial-scale energy production possible throughout the nation [2,3]. North Dakota is currently one of the leading producers of oil in the U.S. , with more than 9,600 active oil wells at the end of 2013, approximately double that of eight years prior, with most development occurring in the Northwest .
We selected two study areas, Belden and Blaisdell, with the goal of gathering data from areas with similar land use but differing levels of oil and gas intensity based on relative oil well densities (Fig 1). Study boundaries were constructed using 95% minimum convex polygons around sharp-tail nesting locations from 2010–2011 (A. C. Robinson, North Dakota Game and Fish Department, unpublished data). Study areas were located in Mountrail County, North Dakota and were approximately 15 kilometers apart from each other.
This study is one of the first to simultaneously examine differences in both predator and prey relative to high and low levels of energy development. Although only correlative, we found a relationship between predator occurrence and nest survival relative to our study sites. Based on current literature we originally expected the direction of this relationship to be opposite of our findings. Instead, we observed higher meso-mammal occupancy and lower daily nest survival rates at our area of minimal gas and oil development (i.e., Blaisdell), and the opposite was observed at the adjacent area of intense gas and oil development (i.e., Belden). We hypothesize energy development in North Dakota is indirectly influencing sharp-tail nest success by altering local predator activity.