Muleys Moving 150 Miles, Study Finds

The movements of muleys has long fascinated me. Each fall I lurk in ambush hoping that one of the Pasayten’s big mosshorns meanders my way.

A couple seasons ago I watched silently as a train of 13 does and fawns mewed their way within 30 yards, if that, as they made their way to lower ground for the winter.

When I reported it down at the deer check, Scott Fitkin turned to fellow biologists and wondered if the migration had begun.

Over the years I’ve spoken to he and one of his predecessors in Okanogan County to learn more about the wily ways of those big-eared bounders.

While not all the Methow’s muleys go on such long journeys, over the years a buck or two has been known to travel 50 miles between summer range up in the wilderness or southern British Columbia, and the winter range fringing the upper valley.

Even if that sounds far, it’s just a third of the distance one Wyoming herd of 500 muleys was recently discovered to travel — 150 miles — between the Red Desert and Hoback Range, an amazingly long intact corridor in this day and age.

It speaks to the high-elevation nature of the Cowboy State and what something like nine out of every 10 big game critters there needs to do to get by.

“The … route also reminds us why so many of Wyoming’s ungulates migrate – because it is a seasonal foraging solution to living year-round in Wyoming’s dynamic landscapes and climatic conditions. It allows deer to access the abundant forage of Wyoming’s mountain ranges, but escape the deep snows that winter brings,” researchers at the University of Wyoming write in the Mule Deer Migration Assessment, released earlier this week.


This herd’s movement — believed to be the longest in North America — is at potential risk from energy development and habitat loss. That’s caused a new behavior, speeding through areas of wellheads and whatnot, elsewhere in Wyoming

It can actually be a bad thing because the deer don’t just go on one long, uninterrupted walk in spring. Rather, they halt at numerous “stopover” points to refuel.

For instance, in the Methow, the Rendezvous, that big, open south-facing slope just north of Winthrop, is a key place for local muleys to “reverse their energy deficit” coming out of winter before continuing further into the mountains, WDFW’s Woody Myers has told me.

In Bend, Ore., where the herd is in long-term decline, a study found that development is “increasingly infringing on mule deer habitat and blocking passage between the deer’s summer and winter ranges.”

One of the most interesting of the maps in the Wyoming researchers’ 56-page PDF shows how I-80 was an almost complete barrier to the critters in the winter of 2011-12, preventing them from accessing areas to its south that would likely have had less snow cover.

Pretty interesting stuff.

For more, see the Casper Star-Tribune’s article on the study, a 3-minute video on Vimeo by one of the researchers, and the report itself.

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