A federal order that told Western states to start mapping the big-game migration corridors on their landscapes turned eight this year, and the running total is 237 routes across 11 Western states.
The Interior Department order, signed in 2018, gave state fish and wildlife agencies a shared framework and a funding path for mapping the seasonal migrations of mule deer, elk, and pronghorn. Eight years in, the states involved have mapped 237 routes. The Western Association of Fish and Wildlife Agencies runs the state-level coordination. Federal science support runs through the U.S. Geological Survey’s Corridor Mapping Team, which is based at the Wyoming Cooperative Fish and Wildlife Research Unit.
The scale of these migrations is not intuitive from a road map. Mule-deer herds routinely move a hundred miles or more between the high country where they spend summer and the low sagebrush basins where they winter, and the longest mapped mule-deer migration in Wyoming runs about 150 miles one way. Elk and pronghorn routes follow similar patterns at different scales. When a road, a fence, or a subdivision cuts one of these routes, the animals don’t reroute — they thin.
Hunters were the first constituency to press for the order in 2018, and hunter-backed conservation groups have been the reason it has stayed in place across three federal administrations of both parties. The order does not put land off-limits. It maps the corridors, ranks the pinch points, and directs federal partners to work with the states on fencing modifications, wildlife-friendly road crossings, and easement work with willing private landowners.
The next phase, taken up at this year’s summer meeting of the state fish and wildlife agencies, is stitching individual mapped routes into a connected migration network — a landscape-scale view that lets a state agency see how one crossing project 40 miles from a hunter’s tag unit might affect the herd he draws for. That connected view is what state biologists have wanted since the order was signed. The mapping done so far gives them enough of the raw material to try.
