Mule Deer Hunters —
Are You In The Know?
by Diane Tipton
Test Your Knowledge

What factor or factors have the most impact on mule deer numbers?
• precipitation
• natural mortality
• habitat type and conditions
• predation
• temperature
• winter severity
• hunter harvest

Why is it important to know the number of fawns in a mule deer population compared to the number of adult mule deer?

How many different types of mule deer habitat are there in Montana?

How often and when are mule deer counted in the state?

How does FWP know if there are enough mule deer in an area to warrant a liberal hunting season?

The Plan

Mule deer may be commonly seen in Montana, but they are uncommonly interesting to learn about. Answers to these questions and more can be found in two places — Montana Fish, Wildlife & Parks' spiral-bound Adaptive Harvest Management plan (AHM) and in the field with deer biologists and wildlife managers across the state.

The field may be the popular choice. But, make no mistake, the spiral-bound version is very interesting reading. The text of the AHM plan will be available beginning April 23 on the FWP web site at

"AHM maps what biologists have learned firsthand in more than 25 years of field work with mule deer," said Glenn Erickson, FWP Wildlife Division wildlife bureau chief. AHM brings annual mule deer surveys, long-term average population statistics, annual weather conditions, and harvest statistics, together with hunting regulation packages tailored to the five unique mule deer habitats in the state.

"For the first time we have the critical causes and effects in one place," Erickson said. "Now we're in a position to learn even more about how nature and hunters impact mule deer."

Annual monitoring of deer populations is the foundation of mule deer management and it helps drive FWP's annual hunting regulation recommendations. Aerial surveys are conducted in 13 census areas (where spring surveys are flown three times to increase levels of accuracy and winter flights are flown once) and 67 trend areas (where both spring and winter surveys are flown only once). The 13 census areas are each similar in size to the Highwood Mountains east of Great Falls and they are the core areas where extra time is spent to collect accurate and consistent data that is fed into computer population modeling efforts. Trend areas provide supplemental information that help fill in the gaps across these large geographic areas. The winter or post-hunting season flights are flown in December and January and the number of bucks, does and fawns retallied at that time.

Spring flights from March 15 to April 30 reveal the number of fawns that survived winter, the number of fawns per 100 adults, and total winter survival of mule deer. Census areas get the closest scrutiny in spring with flights repeated three different days in close succession to ensure counts are accurate. In spring, fawn numbers are tracked per 100 adults because, from the air, does are hard to distinguish from the bucks that have shed their antlers.

While the spiral-bound version of AHM is good reading, the aerial view is where research and reality meet.

The Plan In Action

"With the winter post-season surveys I have only one flight to get it right," said Shawn Stewart, FWP deer specialist in FWP Region 5, Billings and the surrounding area. Stewart chooses his flight days carefully. "There are times when the winds in these steep canyons and the high country can blow you right out of the sky."

Ideal weather for counting mule deer is calm and sunny, he says, admitting 60-80 mph winds are common in the areas he works. Experience also taught him not to survey soon after a snow because deer tend to "timber up."

Tools of the trade are basic: a yellow legal pad, pencil — and a GPS device. "I mark where I tend to see deer from one year to the next and go back there first to relocate them," Stewart said. The average trip is six hours — including an hour of "ferry" time.

Examples of three of the five mule deer habitats in the state can be found in FWP Region 5: Prairie/Mountain Foothills, Southern Mountains, and Prairie Breaks. The other two habitat types in the state are Mountain Foothills and Northwest Montana.

"The spring fawn-to-adult ratio and doe mortality drive the system," Stewart says. "They tell us whether the herds are maintaining, growing or shrinking."

Fawn survival into the spring is in part due to precipitation and temperature the summer before. Dry summers with little to eat means fawns will lack the fat stores that could help their winter survival. The last significant dip in mule deer numbers in the area Stewart monitors in eastern Montana was in 1996-97, when hunters saw more restrictive hunting regulations. Since then, increasing numbers of fawns have survived the past few winters and population counts are trending up again, bringing less restrictive hunting regulations in some areas.

Stewart's post-season surveys show in the neighborhood of 50-60 fawns per 100 does. He predicts spring surveys will show 40-60 fawns per 100 adults. "It's been a good year for mule deer, even with last summer's drought, because winter was relatively mild."

To the north in FWP Region 6, Glasgow and the surrounding area south to the northern shore of Fort Peck Lake, is exclusively Prairie Breaks mule deer habitat. Post season fawn-to-doe ratios this year ranged from 35 to 72 fawns per 100 adults with most counts in the 60s — near average for this region.

Spring "recruitment," or the number of fawns that survive their first year to become additions to the population, can vary widely in the Prairie Breaks habitat from less than 30 fawns per 100 adults in poor years to more than 60 fawns per 100 adults in good years.

"We're anticipating that upcoming spring surveys will show continued recovery of mule deer," said Ray Mule', FWP deer specialist in Culbertson. Total numbers of mule deer in this year's post-season surveys were average to above average and fawn-to-doe ratios were satisfactory. The winter was relatively mild here too, except for the extreme northeastern part of the region. Spring surveys from last year showed mule deer numbers were higher than the year before, and were above the long-term average on eight of 12 count areas. Also, in general the number of fawns per 100 adults counted last spring were above average.

Back down to southwestern Montana and FWP's Region 2, Missoula and the surrounding area, wildlife manager John Firebaugh reports post- season surveys show fawn-to-doe ratios of 40-50 fawns per 100 does. "If we get to spring green-up and find we're still in the range of 40 plus fawns, it will be a real shot in the arm for mule deer again this year," he said.

Mike Thompson, a biologist in the region, says 50-80 fawns to 100 adults is "the same old deal" — a deal biologists like because it means continued good recruitment of young into the herds. "On the plus side, you can have quite a bit of variation and still be in good shape. But when we count fawns in the 30s per 100 adults in this type of Mountain Foothills/Northwest Montana habitat, that's definitely not a good deal," he said.

In that case he would verify the numbers, look for the root causes and recommend restrictive hunting season packages that won't add to an already too high mortality rate.

How do biologists know when mule deer numbers are high enough to warrant a liberal hunting season? The fawn recruitment rate reveals whether or not the population will continue to increase and that is what the spring surveys are designed to uncover. The results will be available in May.

Liberal, standard and restrictive hunting regulation packages, already correlated to annual hunter success rates over the years, help biologists anticipate what the results of their recommendations may be. Regional recommendations on regulations go out for public comment at a number of public hearings across the state, and then to the FWP Commission for final approval every winter.

"The Commission is where the deer surveys, fieldwork, and past statistics meet up with public opinion," Erickson said. "Everyone, hunter or not, has a personal opinion of how the mule deer in their area are doing and they care deeply about them. AHM gives them a map to follow to understand how we manage this important species."


Region 1, Kalispell Jim Williams 751-4585

Region 2, Missoula John Firebaugh 542-5516

Region 3, Bozeman Joel Peterson 994-6936

Region 4, Great Falls Graham Taylor 454-5860

Region 5, Billings Charlie Eustace247-2960

Region 6, Glasgow Harold Wentland 228-3710

Region 7, Miles City John Ensign 232-0921

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