A recent study conducted by researchers from the University of Wyoming, the University of Florida, the University of Nebraska-Lincoln, the University of Arkansas and the Northern Plains Agricultural Research Laboratory has revealed that many pronghorn herds in Wyoming are experiencing long-term declines in fawn production. These declines have been attributed primarily to oil and gas development and the encroachment of trees. The researchers analyzed data collected by the Wyoming Game and Fish Department from 40 pronghorn herds over a 35-year period from 1984-2019 and also looked at region-specific data related to oil and gas development, roads, fire, invasive plants, tree encroachment, and precipitation patterns.
The research team found a correlation between long-term declines in pronghorn productivity and increases in oil and gas development and woody encroachment. They noted that both tree cover and oil and gas development have increased significantly across most herd units in Wyoming over the past 40 years. While other factors such as nonnative grass invasions, wildfires, roads, and increased winter precipitation were identified as potential threats to pronghorn, they were not found to be prominent drivers of the declines in pronghorn productivity observed in the study.
While oil and gas development is already known to impact Wyoming’s rangelands and the species that inhabit them, the researchers highlighted that tree encroachment is not typically viewed as a threat to the state’s sagebrush ecosystems. However, even low levels of invading trees can have significant impacts on sagebrush-dependent wildlife like pronghorn. The increase in trees could provide cover for predators, lead to loss of forage associated with sagebrush and grassland cover, and cause pronghorn to avoid these areas.
The researchers suggest that efforts to prevent and manage tree growth in sagebrush ecosystems could be crucial for maintaining Wyoming’s pronghorn populations. This could involve manual removal of trees and controlled burning to mitigate the impact of tree encroachment on the habitat of sagebrush-dependent species. The study emphasizes the importance of early management of invading trees within sagebrush habitat to protect iconic rangeland species like pronghorn, stating that preventative measures and early intervention are the most impactful and cost-effective approaches to managing the encroachment of trees.
Overall, the study underscores the importance of addressing the factors contributing to the long-term declines in pronghorn productivity in Wyoming. By understanding the impacts of oil and gas development and tree encroachment on pronghorn populations, researchers and wildlife management agencies can work towards implementing effective conservation strategies to protect these iconic animals and their sagebrush habitat. Efforts to manage and prevent the growth of invading trees within sagebrush ecosystems are seen as crucial in maintaining and potentially increasing pronghorn numbers in Wyoming.