GPS Tracking Collars Being Used to Understand Mule Deer Migration
5 Apr 2016The Grand Teton National Park, partnering with the Wyoming Migration Initiative, launched a study this spring of large mule deer across the state.
National Park Service biologist, Sarah Dewey was unclear about where the deer that she collared with GPS tracking devices back in November would go.
Generally, the deer went west around the Jackson Lake at the North end and crossed the Snake river going up the Teton Range’s eastern flank. Then they would eventually cross the mountains and make it to Idaho descending down the west slope. This 45-mile trek which Dewey had not seen yet, going to winter range entailed over 2,000 feet of vertical climbing.
This new route, along with three others, has been documented recently in order to understand where the mule deer of Grand Teton are going once they leave the park.
It was in the late 1990s when animal migration started being studied by the park and included species like the osprey and red-tailed hawks. Radio collars were eventually used to track bison, moose, and bighorn. However, the long-distance migrations were hard to document.
About 15 years ago, with the help of the GPS tracking collars, for years at a time researchers were finally able to gather up the animals’ location data wherever they moved. According to Dewey, this new technology enabled researchers to conduct projects such as characterizing the renowned migration ‘path of the pronghorn’ in the 2000s.
In 2013, two deer were collared with GPS devices by biologists during a Grand Teton pilot study. One of the collared deer was near Colter Bay, the other Flagg Ranch. Both animals were expected by Dewey to head west, however they both traveled east. It took one of the deer 10 days to travel 66 miles to the Shoshone River’s North Fork and the other took around 2 weeks to travel almost 75 miles to the Shoshone’s South Fork. On its journey, the latter crossed the Absaroka Divide and a few high mountain passes.
Six more deer were collared by Dewey and her colleagues in 2014 in the Grand Teton’s northern part. One of the deer went to the Shoshone’s North Fork and one went to the Gros Ventre drainage from the Teton Front making it across the Continental Divide and ended up 95 miles away from its beginning location near Dubois. The other four went to the South Fork location.
Observational and anecdotal information was obtained by the biologists on the locations the deer were migrating. Dewey said, they were finally able to document the migrations.
Dewey wishes to gather more data since in order to make a scientifically valid sample and inform scientists of what the real migration experience is like on all routes, it takes more than one animal. Her plans are to collar more deer and continue gathering data.
The GPS tracking is just a start, however, as the next stage will be talking with non-government organizations, agencies, and private landowners about preserving these migration routes.
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