Fire & Drought
Test wildlife, Too


Game Range Ramblin's


Game Range Articles
by Mike Thompson,
FW&P wildlife biologist,
writing for the Pathfinder

 

 

August 17, 2000
Seeley Swan Pathfinder
Seeley Lake, Montana


by Mike Thompson,

Fires burning over many thousands of acres this summer are reshaping and redefining wildlife habitat on a scale seldom witnessed during the previous 80 years in western Montana.

And, the extreme heat we've experienced since mid-July, as well as ever-worsening drought conditions that set in over a year ago, have added a weather stress that affects us all.

What about our wildlife?

Certainly, fire and drought are natural and not too uncommon occurrences that native wildlife species are evolutionarily adapted to cope with, just like deep snow and cold temperatures. But, like snow and cold, it is reasonable to expect that drought and heat can severely stress individual animals and test their genetic fitness.

It's not pretty, but that's how wild species and populations adapt to their environment. By being tested under occasionally extreme conditions. And, by naturally culling those individuals that are proven unfit to pass on their genes. In this way, the surviving population, although sometimes temporarily reduced in number, emerges stronger in the long run.

So, is this the introduction to an article predicting gloom and doom for wildlife?

Not yet. But, what are the risk factors?

Perhaps the most obvious risk factor today is a flaming forest. Back in 1988, when the Canyon Creek fire was burning through the Scapegoat Wilderness and beyond, Montana Fish, Wildlife & Parks (FWP) was fortunate enough to have some radioed elk in the path of the fire. So, we can offer a bit of insight on how elk react when their habitat is burning. I quote from a 1988 progress report by Mark Hurley, who was the graduate student working on the elk study at that time:

"The Canyon Creek fire in the Scapegoat Wilderness did not cause any significant movements of elk in the area. The elk seemed to move just far enough to be out of the path of the fire. Elk were observed within 1 kilometer (0.6 mile) of flames several times."

At the opposite end of the wildlife spectrum from large, mobile elk are reptiles and amphibians. The moist, permeable skin of amphibians would seem to elevate their vulnerability to heat and drying. But, a literature review published in the Summer 1999 issue of Wildlife Society Bulletin indicates that, "Overall, amphibians and reptiles did not appear to be disturbed by approaching fire and responded in adaptive manners that minimized mortality. For example, large breeding choruses of frogs have been observed in wet areas immediately after fires, surrounded by still-smoking ashes."

Although research was conducted in a vastly different environment than ours, the same Bulletin article presents an interesting observation on rattlesnakes: "Means and Campbell (1981) examined effects of prescribed burning on a population of eastern diamondback rattlesnakes in Florida. Of 68 individual rattlesnakes marked and captured in a forest subjected to 5 prescribed fires in as many years, only 2 snakes were killed by burning. Both snakes were shedding their skin, which may have hampered their sensory perception and consequently their ability to detect and disperse away from approaching fires."

Common sense dictates that native animals are well adapted to escape a flame, unless individuals become trapped in some way or simply run out of luck. But, how do they handle day after day of unusually intense heat?

Recent research from eastern Oregon suggests that elk can withstand many days of summer temperatures in excess of 77 degrees, without access to any shade, and still gain as much weight on the same diet as elk with unlimited access to shade.

But, this summer we're talking about prolonged periods with temperatures in the 90's and higher. There is speculation and limited evidence in the scientific literature that such high temperatures cause elk to increase their metabolismburn more energyto cool themselves under extended periods of intense heat. Basically, elk sweat, but they do so at a cost of increased energy loss. They also may decrease food intake, which may be an added stress to nursing females and their young calves.

Then again, there's the example of a well studied, wild elk population that colonized a semi-desert region of southern Washington a few years back. This population of elk increased at a remarkably high rate, despite enduring conditions every summer that would be comparable to or worse than those we're experiencing this year.

Perhaps more important to elk than the heat itself is access to water and good food. If both are available, elk can be expected to handle heat stress without measurable effects on calf production or survival. And, it's surprising how long elk forage can retain its green, succulent quality under a thick forest canopy next to a seep or spring, even in this searing heat. However, vegetation started drying out unusually early this summer, and if the drying persists late into the fall, we may see some lowered calf counts in the next year or two.

The bottom line? Our wildlife is almost certainly handling this extreme summer weather a lot better than we are. But, that's not to say there isn't a little more stress than usual in the wilds. I would say that weather patterns this coming fall, winter and spring will have a much greater potential effect on wildlife than the weather we've experienced so far.

So, it's wait and see.

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