On the Move: Mule Deer

NPS Photo/J Tobiason

Mule deer struggle to survive in the extreme winter snow of the Greater Yellowstone Ecosystem, and they are not well adapted to the arid, high-desert, lands south or west of here. Over time, they have discovered a migration route that lets them find the best summer food here and then escape the extreme winters by traveling to the far-off high deserts.

Today, mule deer migration is threatened by roads, fences, and even whole neighborhoods that can pop into existence faster than the deer can adapt. We need to understand how mule deer migrate if we are to help them survive.

“I don’t have to take a trip around the world or be on a yacht in the Mediterranean to have happiness. I can find it in little things, like looking out into my backyard and seeing deer in the fields.”

– Queen Latifah

As early as the 1920’s wildlife researchers like Olas Murie tracked and observed these migrations on foot and knew something important was going on. Later, researchers in Idaho tracked mule deer with radio collars and realized migration was key to their survival. Today we have automated collars with precise GPS tracking that gives us a look into this mysterious migration that was staring us in the face for the last 100 years.

With this research, we know more about what a mule deer needs to survive than ever. We know that small groups move together across the landscape and that mothers teach their fawns a route that is passed down through generations. We know that on their routes the thousands of deer move across a patchwork of public and private lands, roads, farms, through towns, and over mountains. We know that if we are going to continue to have mule deer here in Grand Teton, the people who manage those lands need to work together.

 

AdobeStock/413667159

Here, There, Everywhere!

Twice a year, mule deer from Grand Teton may travel as short a distance as 40 miles or as far as a couple hundred miles. Along these impressive journeys to and from their wintering grounds, they often cross a number of waterways, including large rivers such as the Snake, Yellowstone, and Green rivers. High mountain passes are frequently included in their route, with mule deer traveling east crossing the Continental Divide.

Each spring, mule deer will “surf the green wave”, as they follow the green-up of plants, eating the most nutrient-rich plants along their journey. Riding this wave may mean a journey of a few months, as winter slowly gives way to spring. The habitat along this journey is just as important as the winter or summer stopovers.

The four mule deer highlighted here have quite different journeys. Deer #9 embarks on a “short jaunt” of 43 miles, traveling over the Teton Mountains to winter in eastern Idaho. Deer #2 and #8 winter along the Shoshone River near Cody, WY. This harrowing journey involves crossing rugged mountains and high mountain passes where snow may await them in both the fall and spring! Finally, Deer #16 follows the Path of the Pronghorn into the Upper Green River basin. This remarkable journey is 130 miles and crosses a diverse range of landowners, including National Park Service, Forest Service, Bureau of Land Management, state, and private, highlighting the boundaryless nature of migration.

 

 

Mule Deer #2 crosses the Two Ocean Plateau of Yellowstone National Park and traverses three mountain peaks in the rugged Absaroka Range before reaching its wintering grounds along the North Fork of the Shoshone River west of Cody, Wyoming. Total distance: 66 miles

 

Mule Deer #9 journeys around Jackson Lake before crossing the northern reaches of the Teton Range into eastern Idaho. After departing the mountains, this deer travels across farm fields and a state highway to winter along the Teton River east of Rexburg, Idaho. Total distance: 43 miles

 

Mule Deer #8 traverses the remote Teton Wilderness Area before crossing lshawooa Pass at over 10,500 feet in elevation. This deer then rapidly descends into its winter range in ranch lands along the South Fork of the Shoshone River southwest of Cody, Wyoming. Total distance: 75 miles

 

Mule Deer #16 follows the Path of the Pronghorn through the varying topography of the Gros Ventre Range before crossing into the Upper Green River basin. This deer continues south past Fremont and Boulder Lakes to its winter range near Farson, Wyoming. Total distance: 130 miles