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Mule Deer Numbers Growing Steadily


April 6, 2000
Seeley Swan Pathfinder
Seeley Lake, Montana


by Mike Thompson,
Wildlife Biologist
Montana Fish, Wildlife & Parks
"Game Range Ramblings" column Seeley Swan Pathfinder

 

The report from the Airborne Division of Montana Fish, Wildlife & Parks (FWP) is that your mule deer population is growing in the Seeley Lake area.

Yes, it's that time of year once again. When biologists awake to the permeating stench of aviation fuel in the morning. When the whap! whap! whap! of helicopter blades is the music that accompanies our days. When virtually invisible powerlines command as much of our attention as the deer that invariably seem to congregate beneath them.

But, the deer are what we seek. And, not just any deer. Mule deer. The deer species that reminds us we live in the West, instead of New Jersey. That big-eared, stiff-legged, gray-haired variety that's improving the standard of living for aviators all across Montana.

Because the public demands that FWP upgrade its monitoring of mule deer populations. So, we've increased the number of mule deer survey areas in Montana over the past few years. That translates into more hours for more biologists and pilots in more helicopters.

Would it surprise you to learn that the Blackfoot-Clearwater Game Range was selected as one of several key survey areas for mule deer in FWP Region 2?

Well, I hope you're used to living on the leading edge by now. Of course, we were surveying mule deer on the Game Range long before anyone told us we had to. But, FWP's recent emphasis on improving its statewide mule deer management has caused us to elevate the frequency and intensity of our surveys.

We've selected a portion of the Game Rangebasically, the 1991 burnas the area we will survey by helicopter annually, using the protocol prescribed by FWP's deer experts in our Bozeman Research Bureau. We selected the burn because it's located on a fairly distinct unit of deer winter habitat with deer that are faithful to it (according to data from banded mule deer in 1991-93). It's also a lot easier to get a consistent count where the trees are burned off than it is in the forests of Boyd Mountain. Hopefully, any changes in numbers of deer we count from one year to the next will reflect actual changes in the population, rather than variations in survey efficiency.

If the early results are any indicator, this new survey protocol will allow us to monitor trends in the local mule deer population with adequate precision and accuracy. Let's look over our results from the past three winters.

We began our special mule deer survey in January 1998, counting 289 deer in this relatively small survey area (about 8 square miles). The following April, Jamie Jonkel counted 294 deer in the same area. After much discussion, we rejected the theory of spontaneous generation in mule deer, and concluded that the increase of 5 deer between January and April was merely a reflection of survey imperfections and some minor shuffling of deer between winter habitats on the Game Range.

A comparison of fawn numbers between January and April also leads to the conclusion that 1998 was a mild winter with low predation. We counted 76 fawns on the survey area in January and finished with 71 in spring.

So, there should have been more deer in 1999. Lo and behold, there were. Jamie counted 317 in January and I returned to count 334 at the end of March. We even appeared to gain 25 fawns between winter and spring, which would cast doubt on my notes from Biology 101 if we didn't realize that some deer move in and out of the survey area between winter and spring. Despite imperfections in our data, we can at least conclude that winter mortality was low in 1999 as well.

So, mule deer numbers should still be climbing. And, they are. This past January, Jamie counted 367 deer, an increase of 50 over the previous winter. He returned last week for a spring count of 355 deer, showing an increase of 21 deer from my spring count the year before. In winter, he found 125 fawns where only 106 fawns were found this spring. Jamie asks us to cut him some slack on the exact fawn numbers. (He says it's pretty hard to sort fawns from adults in a group of 153 bounding and scattering deer.) We'll wait for the results of his spring carcass survey before speculating that a few more mule deer may have died this winter than in 1998 or 1999.

As I noted at the conclusion of last week's column on white-tailed deer, data on the local mule deer population merit closer inspection for clues to the cause(s) of low calf survival in our elk herd. If we're concerned about increased predation rates on elk calves, shouldn't we expect to see some influence of increased predation on deer populations as well? If we don't see evidence of increased predation on deer, can we narrow our focus on predator species or other factors that would have a greater effect on elk than deer? We won't solve this problem today, but we will keep working on it.

 

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