In Wyoming, mule deer unify diverse communities, boost the state economy, and provide an iconic western aesthetic loved by many. From mansion dwelling millionaires in Jackson, to hard working oil workers in Rock Springs, mule deer and their migration routes traverse economic and cultural boundaries that divide the state. Mule deer provide many Wyomingites with meat in their freezer and others with a sense of wild and wonder. Unfortunately, mule deer populations are not iron clad and are susceptible to numerous factors that can diminish herd numbers. Fragmented migration corridors, energy development, roads, fences, climate change, disease: all are factors that contribute to waning heard counts and the ability of deer to thrive in the west. According to a 2018 report from the Wyoming Game and Fish Department, mule deer numbers have declined by 31 percent across the Cowboy State from 1991 to 2016.
Fortunately, for the deer and those who love them, scientists at the Wyoming Migration Initiative (WMI) are doing everything in their power to gather critical data that will help these animals persist through time. Anna Ortega, a PhD student with WMI at the University of Wyoming, studies the world’s longest mule deer migration: a 150-mile journey from the Red Desert near Rock Springs to the Hoback and Upper Green River Basins near Jackson Hole. Ortega’s research investigates how three different migratory strategies within the Sublette Mule Deer Herd persist over the long term. Some members of the herd travel the world record, 150 miles and within the last year, Ortega and her colleagues discovered one individual that migrates 242 miles to Island Park, ID. Other members of the herd, however, only travel 70 miles to the southern Wind River Range for the summer and some remain residents year-round within the Red Desert. Ortega hopes that her research can fuel conservation efforts and provide managers with the tools and data they need to properly manage this iconic herd.
On December 7th, Ortega and a team of scientists recaptured 85 deer on their winter range in the Red Desert. They collected blood samples to gain insight into hormones, disease, and genetics, fecal samples for diet, and conducted ultrasounds to quantify how much fat these deer gained after spending time on their summer ranges. For deer, fat gain is a crucial component to survival. Fat gain can determine who survives the winter, who breeds, and can affect the weight and condition of young. After collecting the samples, the scientists carefully check the GPS collars and release the deer back to the wild. They will follow their movements over the following months and year.