How Do Wildfires Impact Deer and Elk?
by Mike Hillis
Broadcast 10.23 & 10.28.2016

wildfire in the Bitterroot National Forest, with two deer standing in a river

Wildfire in the Bitterroot National Forest. Photo by John McColgan, public domain.

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While watching an evening newscast about Montana wildfires, I saw some TV footage of deer and elk fleeing burning areas and listened to speculation by the newscasters of how many animals might be killed during the fires. I was reminded of watching the movie Bambi as a child, and fearing for Bambi’s life as he fled that fictional wildfire many decades ago.

So how devastating are wildfires to deer and elk? Can most of them outrun or outflank a rapidly spreading fire? And what about the survivors when they return to a burned forest? Isn’t their habitat destroyed?

I decided to do some investigation, starting with the Canyon Creek fire in 1988. While that fire burned for months, most of the quarter million acres was consumed in a ferocious, wind-driven run over Labor Day weekend. With that incredible rate of spread, one would have thought that thousands of elk and deer would have perished. But according to the Montana Department of Fish, Wildlife and Parks records, only a few dozen elk could be documented that actually succumbed to the fire. Next spring’s Fish, Wildlife and Parks aerial elk counts confirmed that the vast majority of that elk population survived the fire.

Still unconvinced, I consulted The Elk of North America, published by the Wildlife Management Institute in 1982, a compendium of elk research conducted over the last century. When I consulted the index under “fire-caused mortality”…nothing! That 698-page book discussed elk mortality caused by everything from grizzly bear predation to rheumatoid arthritis—but no mention of wildfire as a significant cause of mortality.

How about deer, then? Maybe being smaller they’re more vulnerable to rapidly-spreading wildfires. I consulted Mule and Black-tailed Deer of North America, compiled by Olaf Wallmo in 1981. Same story. That text was equally devoid of wildfire as a direct threat to deer.

OK. So it sounds like elk and deer are pretty adept at avoiding even large rapidly-advancing fires. But what about the effect of fire on their habitat?

Here’s where I have some personal experiences. Over the last 15 years I’ve clipped and weighed forage plants on hundreds of acres of deer and elk winter ranges across the Lolo National Forest. The results are totally predictable. On winter ranges where fires have not burned for more than 20 years, an acre of winter range will typically yield from 30 to 120 pounds of forage. On winter ranges that burned in the last year or two, however, the production typically jumps to 200 to 3000 pounds of forage per acre—over a 20-fold increase in forage production. This is not news to wildlife researchers. It means that fire is not only beneficial to deer and elk, but essential if our goal is to have large numbers of deer and elk in our forests.

Paradoxically, while the literature is conclusive that fire is beneficial to mule deer and elk, I found a reverse relationship for white-tailed deer.

My friend Ross Baty did his master’s research studying the food habits of elk, mule deer, and white-tailed deer on the Blackfoot Clearwater Wildlife Management Area. During his study, a large, late-season wildfire burned through the area in October 1991. He found that, as expected, elk and mule deer responded positively to the fire…but white-tailed deer did not. Why? Simply stated, it’s because whitetails eat different stuff. Whereas elk and mule deer forage on shrubs and grasses that increase after fires, whitetails eat arboreal lichens and Douglas-fir, plants that decrease after fires.

It’s pretty simple if you think about it this way—elk and mule deer evolved in the arid west where wildfires are common. Whitetails evolved in the rain-abundant eastern part of the U.S. where fires are uncommon. Does that suggest that whitetails are a recent immigrant to the arid west? Perhaps, but that’s another story.

Well, no doubt about it, wildfires are pretty devastating to those people who lose homes and belongings. The smoke is certainly an inconvenience at best and a health hazard at worst for the rest of us. But don’t worry too much about the fate of mule deer and elk out there. Trust me, they’re not as stressed as you might think!