Effect of Oil & Natural Gas Development on White-tailed Deer Populations

Energy Development & Wildlife
Oil and natural gas extraction has expanded in Western North Dakota and Northwestern South Dakota in recent years. Research in Western states found that expanding oil and natural gas development can negatively impact many wildlife species, especially large mammals such as mule deer, elk, and pronghorn. No research has been completed on impacts of development on white-tailed deer, and white-tailed deer responses to expanding oil and natural gas development have been unknown. A project involving North Dakota Game and Fish Department (NDGF), South Dakota Department of Game, Fish and Parks (SDGFP), and South Dakota State University (SDSU) has investigated the impacts of oil and natural gas development on white-tailed deer health and survival in Dunn County, North Dakota, an area influenced by energy development, and Grant County, North Dakota, and Perkins County, South Dakota, areas not influenced by energy development at this time. Researchers believed oil and natural gas development would decrease deer survival and health.

Deer Survival
Adult female and fawn survival differed between study areas. Female survival was 96% in Dunn County, 75% in Grant County, and 93% in Perkins County. Fawn survival was 75% in Dunn County, 40% in Grant County, and 78% in Perkins County. Oil and gas development does not negatively impact white-tailed deer in the Western Dakotas at this time. Survival among study areas could be related to deer density. A low deer density in Dunn County compared to Perkins and Grant counties could be allowing white-tailed deer to find cover and resources away from oil and natural gas development allowing individuals to avoid mortality related to development.

Deer Herd Health
Nutritional indices also varied among study areas, but did not point to oil and natural gas development as the driver of those differences. Sodium is an important mineral for females, because sodium is essential for late gestation and lactation. Low sodium values for females in Grant County compared to Dunn and Perkins counties could be decreasing reproduction in that county and could explain the low fawn survival in Grant County compared to the other two study areas. Differences in nutritional indices could be due to differences in forage quality and availability. A high deer density in Grant County compared to Dunn and Perkins counties could potentially decrease the amount of available quality forage on the landscape and decrease female nutritional indices.

Females were tested for past exposure to a number of pathogens including epizootic hemorrhagic disease (EHD), bluetongue virus (BTV), bovine viral diarrhea virus (BVDV), and many others. One result that stood out was West Nile Virus (WNV). Across all three study areas, 85% of females had been exposed to WNV. Birds are particularly sensitive to WNV infections and often die, but the effects of WNV on mammals is not well known at this time. Researchers believe that WNV may weaken individuals, especially fawns, and increase their risk of death due to other factors such as predation or other diseases. More research is needed to understand the impacts of WNV on deer populations.

In Summary
Overall, this project found that oil and natural gas development does not negatively impact white-tailed deer in the Western Dakotas at this time. Deer and oil pad densities are dynamic, and as both of these densities increase, there is the potential for negative impacts on white-tailed deer health and survival. Continued monitoring in the region will be important to assess the potential impacts of increasing oil and natural gas development on white-tailed deer.

Source: Jonathan Jenks, South Dakota State University, iGrow