Bedford resident Brian Miller carefully walked a strip of boggy lowlands along a ditch in Nugget Canyon, on the lookout for mule deer that starved over the winter. They weren’t tough to find.
In a little over an hour, walking only about 1 mile paralleling U.S. Highway 30, Miller came upon 18 dead deer. Eleven were fawns, but bucks and does had keeled over, too, and there were places where it appeared that mom and the kids had lain down and simply gone to sleep
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“We found 12 in one spot at a turn in the fence,” Miller said.
His fellow volunteers and Wyoming Game and Fish Department personnel walking with Miller discovered 94 carcasses near the bogs north of the highway near mile marker 36. Surveyors on horseback and foot came upon another 92 dead deer in the high country, winter range for the 30,000-strong Wyoming Range Mule Deer Herd.
Some of the dead deer found south of Cokeville that Saturday in early May likely would have migrated well to the north, to summer grounds in the northern Wyoming Range as far as Snake River canyon. Instead they ended up as casualties of winter 2016-17, which left behind twice the average amount of snow in southwest Wyoming and was of a severity that comes around only a few times a century.
“If people want to be upset about not having deer, this is the year to be upset,” said Andy Countryman, Game and Fish Access YES program coordinator, during a break. “But you can’t be upset with anybody but Mother Nature. She whupped us. She whupped us bad.”
In a quarter century of managing big game herds for Game and Fish wildlife biologist Gary Fralick had never seen anything like winter 2016-17. He had to dig through 33 years of data to find a season as severe.
“Certainly this was the most severe winter event that we’ve seen in the deer herd at least since ’83-84,” Fralick said. “And it may be longer than that, too.”
All tracked fawns died
Aerial surveys found that 86 percent of all the fawns in the herd were claimed by the winter. Among the research fawns tracked for the Wyoming Range Mule Deer Project the mortality was even worse. Twenty-six were alive going into the winter, and all died.
“And they’re still dying,” Fralick said while on a break from a survey of the Collett Creek drainage, also south of Cokeville. “There’s still quite a bit of dying in front of us, even in May.”
The cause of death this late into spring is essentially the same thing ungulates succumb to while eating rich feed put out in backyards during winter. Microbes in their guts aren’t adjusted to the green, nutritious, highly digestible food, and the deer end up dying from conditions like rumenitis and toxicosis with their stomachs full.
Winter in the Bear and Green River drainages was as harsh as anywhere in Wyoming this past year, but even where it was relatively close to normal, like in the Snake River watershed, deer herds were hit hard. Comparing ratios of age classes before and after winter, Fralick estimated an 81 percent fawn death rate in the Sublette Herd, which calls Jackson Hole home.
“They suffered just as mightily,” he said.
One purpose of the annual mortality survey — in its 24th consecutive year near Cokeville — is that it helps managers like Fralick deduce how older deer fared the winter. Because antlers have already dropped, springtime ratios of bucks to does are no longer meaningful. By identifying genders and extracting age-telling teeth, the 30-some volunteers who gathered May 6 near Sage Junction were filling in the gaps of how the winter caused the herd to retract.
The lingering effects of winter figure to continue into the future.
By the time March rolled around the Wyoming Range’s doe mule deer had dipped all the way to 2 to 3 percent body fat — a measure of health that is seasonally cyclical, but typically bottoms out closer to 4 or 5 percent.
Precision ultrasound equipment wasn’t necessary to see that the animals were in rough shape, University of Wyoming zoology professor Kevin Monteith said.
“It was very obvious, and almost as if they were just skin and bones,” Monteith said. “They’ve burned all of their fat reserves and most of their protein reserves as well.”
Fetuses inside pregnant does were smaller than they had been in five prior springs of research
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“These are the smallest fetuses that we’ve seen since we began doing this work,” Monteith said.
The lower-weight fawns that make it out alive will be more prone to disease and predation, making it less likely that they will survive to adulthood, he said.
“They’ve got a poor start on life,” Monteith said.
“I hope I’m wrong,” he said, “but I don’t think we’re going to see much in the way of recovery this year.”
A silver lining of the winter 2016-17 for Fralick, Monteith and other ungulate researchers is that it will give them a better understanding of winterkill and how herds and their habitat fare and rebound in the wake of devastating mortality events. The Wyoming Range Mule Deer Project is being extended to measure those effects, and Monteith will bring on a new doctoral student to continue the work of Samantha Dwinnell.
‘Just skin and bones’
“Rarely do we have the opportunity to learn so much,” Monteith said. “This is probably a once-in-many-decades type of winter.”
“In past bad winters, like ’92-93, we knew we lost a lot of animals, but that’s mostly what we knew,” he said. “We didn’t know a whole lot more.
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The historic snowpack left behind a stockpile of moisture in the soil and fewer deer to browse on shrubs that grow on winter range a year from now.
“It’s not only good for the habitat,” Monteith said, “but there’ll be more and better food per mouth that remains.”
Thayne resident Steve Huhtala was one person partaking in the mortality survey who saw winterkill as a natural part of the landscape. Hiking alongside his wife, Libby, Huhtala paused from prying an incisor out of the jerky-like gums of a desiccated deer to muse on the task of the day.
“These little things, I feel bad when I find them,” Huhtala said. “Life’s tough out in the middle of nowhere. It’s part of life’s grand scheme, though.”
