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The Effects of Fire on Animals

by Bruce Auchly

Fri Sep 18 08:32:00 MDT 2015

Summer’s fires are over, right?

All that smoke-in-the-nose, ashes-in-mouth is past for the year. Or so we hope.

Yet even in the worst of it many of us had choices. Some folks left Montana, others sought relief in air conditioning at home or office or both.

Animals don’t have those luxuries. Yes, birds can fly and bears can burrow into a den, but fires in July and August happen at the wrong time for migration and hibernation.

First, let’s slay a rumor. The rash of bear conflicts, mostly black bears, this summer is not because smoke from forest fires was forcing bears out of their mountain redoubts and into towns. They are just farther afield this year looking for food.

Starting in late summer, triggered by decreasing daylight, bears enter a stage known as hyperphagia where they eat for 20 hours a day or more, anticipating winter hibernation. They will eat up to 20,000 calories a day, putting on several pounds each day – don’t try this at home.

To bulk up, they will search many miles for their traditional foods, such as chokecherries and other wild berries. However, this year the berry crop has been spotty at best. Some areas are average, but many spots in central Montana have few or no chokecherries, currants or buffalo berries.

When traditional foods fail, bears don’t stop eating. They just keep traveling, searching for something else to fill their bellies. Unfortunately that can be pet food or pets, livestock feed or livestock, garbage, grease in barbeques, most anything.

That’s why bears are turning up in areas they are not usually found; it just happens to be a year of smoke.

Fire does affect animals, including fish, both in ways good and bad.

As any wild land fire fighter will tell you, not all fires are the same. Some creep along on the forest floor, others burn extremely hot and race through timber.

Animals that can move quickly are temporarily displaced by fires. Animals that cannot out run flames die. Think of young birds in a nest, or small mammals, or reptiles and amphibians. Though a small mammal with a burrow might survive a fast moving fire.

Even large animals, like deer and elk, can become confused, trapped and suffocate.

In the longer term, fire can be a good thing, bringing new succulent growth to the forest floor, which benefits many animals and their predators. Dead trees attacked by insects will attract woodpeckers and other birds to the feast.

Fish are affected by fire, too.

Autumn rains after a hot, devastating fire that burns a forest down to the subsurface can flood a stream with choking ash and mud. Not good.

And not only can small stream temperatures rise to uncomfortable levels for aquatic life from the fire’s heat, the loss of canopy cover and riparian vegetation will decrease overhanging habitat and increase solar radiation. That may mean stream temperatures remain seasonally elevated for years or decades after the fire.

Still, what fire taketh, fire giveth.

Fires free nutrients like phosphorus and nitrogen from terrestrial systems, transporting them into streams and rivers. In this sense, wildfires may be an important linking factor between terrestrial and aquatic systems.

Forest fires and the accompanying smoke make us cough, choke and curse. Then fall arrives and we move on.

To fish and animals fires bring dire short-term and beneficial long-term consequences.