Fall 1998

[TEXT ARCHIVE WEB-PUBLISHED MARCH 2002.
ORIGINAL PRINT PUBLICATION DATE: FALL 1998.]

What about Bambi?

By Alex Blumberg

Well, prairie plants may have regenerative root systems that quickly resprout after fire, and bur oaks may have flame-retardant bark, but all animals, with the exception of certain barnacles, possess an even greater advantage when it comes to dealing with fire — they can move. This ability, combined with the average burn's stately pace of a quarter of a mile per hour, allows most woodland and prairie animals to regard fire with a stunning lack of anxiety.

If you ever had any doubt that Bambi was just a cartoon, says ecologist Wayne Lampa, all you have to do is observe a real deer in a fire. "They just don't seem concerned; a lot of times they'll just hop right over the fire line." And as for Thumper and the little woodland creatures — they have other defenses as well. "Animals have keener senses, so they know in advance that a fire is coming," says Pam Benjamin, a botanist with the Indiana Dunes National Lakeshore, "and a lot of the smaller mammals move underground. Just one inch below the surface and you can't even detect a temperature difference." Does this mean that animals never lose their lives in fires? Well okay, no. "In 10 years of burning, I've seen one snake and one frog killed," says Pam Benjamin. She points out that the occasional snake or mouse found dead after fires may well have been sick or dead before the fire came through. If the fire didn't get it, some predator would have.

One thing is certain though. The losses among vertebrate species pale next to the massive casualties suffered by their exoskeletal cousins. The irony is that most of the rarer insects in the Chicago Wilderness are dependent on habitats which will disappear without regular burn management. Call it the catch-22 of the Karner blue.

The Karner blue, an endangered species of butterfly found at the Indiana Dunes National Lakeshore, feeds exclusively on a flower called the lupine. The lupine depends on fire, while the Karner is what biologists euphemistically call fire-sensitive. It attaches its egg cases to the stalks of dune grasses to overwinter; the grass roots survive a fall burn, the eggs tend not to. While a lot of attention is paid to the Karner because of its rarity, most of the insects in the Chicago Wilderness region sing the same Karner blues — "I'm just a fire-sensitive arthropod in a fire-dependent world."

But Ron Panzer, a conservation biologist with Northeastern Illinois University, hears no sorrow in that song. While true that individual insects die by the thousands, populations of grassland dependent species — even the Karner blue — are entirely dependent on burn management. Panzer conducted one of the most comprehensive studies of insect sensitivity to fire. He discovered that roughly half of all insect species he studied were fire negative — meaning their populations decline immediately succeeding a burn. Of the other half, 25 percent were fire-neutral, and 25 percent actually increased their numbers. The findings were surprising only in that the fire-positive group was so large.

"It probably just means that they'd recovered so fast that by the time we measured them, their populations had actually increased," Panzer says. And this is the reason for Panzer's nonchalance about the fates of individual insects. "If you know anything about insect fecundity," says Panzer, "you know one female can literally lay thousands of eggs." Even if a species lost numbers originally, says Panzer, "most affected populations recover by the following spring and every species surveyed recovered completely within two to three years." Given just a couple years' recovery time, every single insect species becomes fire neutral. But that's the short run. In the long run, the species that depend on grassland and oak woodland habitats die out completely in the absence of fire.

Bottom line: sure you lose insects in each fire, maybe the occasional snake or frog, but that's a small sacrifice for saving an endangered habitat from destruction. As Ron Panzer argues, what are a few individuals when "the data suggest that we've lost entire species due to fire suppression?" Conversely, the more we expand the native ecosystems by restoring the traditional fire regimes, the more we'll discover what Wayne Lampa discovered after instituting a burn program at Waterfall Glen — not only do rare plant species come back, but animals and insects return as well. "For the animals and insects," he explains, "it's sort of like Field of Dreams. If you restore it, they will come."