Mule deer stuns researchers by migrating a world record 242 miles

WYOMING – Wildlife researchers from University of Wyoming were astounded recently when a mule deer numbered 255 made a world record migration from the Red Desert to Island Park, shattering the previous known and standard 150-mile trek by an additional 100 miles.

UW graduate student Rhiannon Jakopak works with mule deer doe 255, the deer with the longest-distance migration route ever recorded. Biologists used blindfolds to keep deer calm during March 2018 captures in the Red Desert of Wyoming. (Benjamin Kraushaar)

The Red Desert provides crucial winter range for deer snowed out of the Greater Yellowstone Region. Come spring, however, mule deer “ride the green wave” following the green-up of grasses north until they reach the Jackson Hole region. This 150-mile migration takes most of the summer and by fall the animals are ready to reverse the trek.

Never had wildlife biologists considered a mule deer would choose to travel farther, crossing the Teton Range and dropping into Idaho.

As amazing as that revelation is, it is not quite the end of the story. The collar mule deer 255 was wearing quit working on August 7, 2016. Scientists were devastated. All hope of finding the doe and where her future journeys might take her were lost.

The fall of 2016 came and went with still no signal. Again, in 2017, radio silence. But this spring, spotter pilots flying helicopter surveillance crews were instructed to be on the lookout for any deer wearing brown radio collars. The model was known to malfunction and it was the exact type 255 was wearing when it stopped working.

Wildlife biologists Anna Ortega and Matthew Kauffman collect a blood sample as part of their work for the Wyoming Cooperative Fish and Wildlife Research Unit. (Benjamin Kraushaar)

Last month, researchers got a break. Helicopter pilot David Rivers spotted a batch of deer with brown collars. He and his crew made a capture and brought the deer to biologists for data collection.

Astonishingly, one of the collars had the serial number “255.” There she was, after 20 months off the radar and three migration seasons later, the mule deer doe that set a record 242-mile journey to Island Park was recaptured a mere dozen miles from where researchers first collared her two years and a day earlier.

Questions remain. The foremost being why would a deer choose to travel farther? Did she discover benefits to ‘summering’ in Idaho rather than Jackson Hole? Is she the only one?

Read the full story from University of Wyoming. It is a fascinating one.

Mule deer 255’s recorded migration. (Wyoming Migration Initiative)

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