Wyoming’s ungulates – deer, pronghorn, elk, and moose- are on the move. Following patterns of weather, elevation, and food availability over eons has led to large groups of animals moving from low elevation areas in the winter to higher elevations in the summer. Spring migration oers animals the youngest, tenderest, and most nutritious plant growth at a time when extra energy is needed to produce the next generation. The reverse pattern allows the animals to minimize energy as they forage in deep snow conditions. These annual migrations are why Wyoming’s harsh winter landscapes can support the vast herds of ungulates we value today. The seasonal routes allow animals to move from summer to winter range and are critical to maintaining these herds.
Wild ungulates in this region have been following their migration paths for millennia. Today the potential impacts on these paths can impact the long-term health of these herds. Some issues are simple barriers, like fences. Others are more complex, like rural development, new roads, and energy development. These do not stop the animals physically but, alter the landscape to the extent few animals are willing to pass through. These semi-permeable barriers can also compromise stopover habitat; the rest stops on the migration routes animals use to refuel and rest along their journey. Bottlenecks, areas of migration routes where many animals pass through a very narrow band of habitat, also need protection. Disturbances in bottlenecks can put the entire migration at risk of being cut off.
The migration routes of ungulates across Wyoming are part of our natural heritage. They are part of what makes our state so wealthy in wild ungulates. Conserving these corridors while reducing and eliminating barriers to migration ensures that we will have healthy herds for the coming years and the next generation.
Why don’t animals migrate somewhere else?
Many animals, including ungulates, follow patterns of weather, elevation, and food availability moving from low elevation in winter to higher elevations in summer. This pattern, following young grasses and forbs, is called “surfing the green wave.”
In spring animals make use of the youngest and most nutritious plant growth. At this time extra energy is crucial to producing the next generation. The reverse pattern allows animals to minimize energy use while traveling in deep snow conditions. This movement pattern dictates a herds “migration corridor.” These are not point-to-point journeys, but are vital habitat areas ensuring the survival of Wyoming herds. Animals spend almost 1/3 of their lives, when they are most vulnerable, on these corridors and pass this food knowledge to the next generation.
Currently Designated or Identified Migration
- Length: 130 miles
- Area: 1,347,621 acres
- Herd Population: 34,500 animals
- Sage Grouse Core Habitat: 235,266 acres
- Critical Mule Deer Habitat: 414,446 acres
- Critical Pronghorn Habitat: 46,798 acres
- Critical Elk Habitat: 493,715 acres
Rather than a single path, the Wyoming Range mule deer migration corridor is a highly
braided set of routes that deer use to pass between the Hoback Rim above Bondurant south
to Kemmerer. The corridor crosses two mountain ranges, the Salt River Range and the
Wyoming Range. The primary management agencies for this corridor are National Forest
Service and the Bureau of Land Management (BLM). There are 1,531 existing oil and natural
gas wells in the corridor, which has been affected by human resource development for
almost 100 years. The corridor is impacted by Wyoming state highways 30, 89, 189, and
- Length: 190 miles
- Area: 837,895 acres
- Herd Population: 35,000 animals
- Sage Grouse Core Habitat: 506,958 acres
- Critical Seasonal Mule Deer Habitat: 120,065 acres
- Critical Pronghorn Habitat: 286,951 acres
- Critical Elk Habitat: 167,019 acres
The Sublette pronghorn migration corridor spans Grand Teton National Park, south and east
through the Bridger-Teton National Forest, through BLM and private land along the upper
Green River basin and Red Desert to wintering areas near Rock Springs. It includes a core
route and equally important side routes. There are 4,911 existing oil and natural gas wells in
the corridor and this area has the potential to be heavily impacted by future development
leases. The corridor is impacted by Wyoming state highways 191, 189, and 351.
Red Desert to Hoback Mule Deer Migration:
- Length: 160 miles
- Area: 624,771 acres
- Herd Population: 24,200 animals
- Sage Grouse Core Habitat: 322,883 acres
- Critical Seasonal Mule Deer Habitat: 190,742 acres
- Critical Pronghorn Habitat: 43,297 acres
- Critical Elk Habitat: 211,048 acres
This mule deer migration route is the original migration that revealed the importance and
the extent of ungulate migration corridors. It is the longest mule deer migration corridor
in the world. This route parallels the Sublette pronghorn migration, ranging from the
low-elevation winter ranges in the Red Desert to the high mountain slopes surrounding the
Hoback Basin. The corridor runs through Bridger-Teton National Forest and BLM land as
well as numerous private holdings. It is relatively free from historical oil and gas development
with only 134 existing wells in the corridor. This is likely one reason for the length of the
corridor and its consistent high-use. Recent efforts by WWF and others have deferred
parcels within the corridor marked for development. The corridor is impacted by state
highways 28, 191, and 189, with highway 28 bisecting the corridor at a narrow point.
- Length: 70 miles
- Area: 73,234 acres
- Herd Population: 10,900 animals
- Sage Grouse Core Habitat: 44,505 acres
- Critical Seasonal Mule Deer Habitat: 33,755 acres
- Critical Pronghorn Habitat: 17,011 acres
- Critical Elk Habitat: 13,078 acres
This corridor is unique. This herd does not move from a single wintering area to a single
summering area. Instead, mule deer are moving from various wintering areas in the Platte
Valley, Sierra Madres, the Snowy Range, and North Park, CO. The paths are diffuse, but
mule deer studied in the region had a high fidelity to their given corridor. This suggests
these routes are long-established and unimpeded passage is critical to the movement
between ranges. This corridor runs through a mosaic of landowners – mostly private with
some BLM included. Unlike corridors in the western portion of the state, this corridor is
relatively un-impacted by oil and gas development, with only 2 wells in the corridor area.
In Wyoming, the migration path crosses I-80, a principal threat to deer travel and
motorist safety. The corridor is also impacted by state highways 130, 230, and 287.
- Length: 60 miles
- Area: 305,785 acres
- Herd Population: 18,800 animals
- Sage Grouse Core Habitat: 185,627 acres
- Critical Seasonal Mule Deer Habitat: 94,186 acres
- Critical Pronghorn Habitat: 29,666 acres
- Critical Elk Habitat: 104,216 acres
The Baggs migration corridor is the shortest of the identified migration corridors in
Wyoming, but mule deer use the same path to move from winter range along the Atlantic
Rim to summer range in the Sierra Madres. The corridor runs through a checkerboard of
BLM and private land. There are currently 137 existing oil and gas wells in the area and
proposed leases in the corridor were deferred in 2019, so it is potentially impacted by future
oil and gas development. This corridor is also impacted by state highway 789.
Support Wyoming Wildlife Federation’s work on migrations and maintaining habitat connectivity in migration corridors by donating during the 2020 Fall Fund Drive.
What We Do To Help
Wyoming Wildlife Federation has a number of specific Programs that address this issue directly. Click on a Program in the list below to explore it in depth.