Catching Sight Of A Rare Butterfly In A Surprising Refuge

On a recent July morning, a tour group gathers at Fort Indiantown Gap, a National Guard training center in central Pennsylvania. They pile into their cars and caravan out to a grassy field. Wildlife biologist Mark Swartz leads them as police direct traffic.

"It takes a lot of coordination," he says. "It occasionally breaks down, and that's when we have problems."

On this day, in fact, Swartz is a bit rattled because the Air Force apparently didn't get the memo. Suddenly he's interrupted by loud noises. "There — they're shooting," he says. "That's a .50-caliber machine gun."

Swartz scrambles to have the training flights rerouted. Once the planes are safely out of the way, he hops out of his car and leads the tour through a field.

A military base may seem a surprising haven for wildlife. It makes sense when you consider that the base has largely kept away people and development. But Swartz says the activities that do take place here actually help create the kind of meadows where the regal fritillary thrives.

"Tanks and other military vehicles ... go in and tear up the ground," he says. "They tear up what would have been trees and turn it back into a grassland."

That landscape supports the plants the butterflies feed on to grow.