Brian Wolslegel's remote-controlled animals can wiggle their ears, move their legs and, in some cases, poop.

These deer, bears and coyotes aren't country-fair booth decoys. His lifelike robotics are the centerpiece of sting operations to nab illegal hunters around the U.S.

"It's about always advancing, trying to stay one step ahead," the 54-year-old taxidermist said.

Wolslegel traveled to a wildlife-enforcement conference in Erie, Pa., this month to showcase his latest invention: a heat-emitting robotic deer.

The new product—assembled from dead animal skin and remote-control car parts—aims to make his decoys even more lifelike, helping officers outfox poachers who have wised up to his earlier models. Some illegal hunters are using thermal rifle scopes to check if the animal gives off body heat before firing a shot.

Wildlife-enforcement officers and poachers have locked horns for decades across the U.S., in national parks, as well as on private and public land. Thousands of violations are issued each year for illegally targeting protected species or not following state and federal hunting regulations; poachers can face hundreds of dollars in fines and potential jail time.

Some are professionals who sell the antlers of the game they shoot. Some are simply new to the sport. "Sometimes it's people messing around on a weekend, and they don't realize what they are doing is a violation," said Christopher Boley, an officer with the Florida Fish and Wildlife Conservation Commission.

At the North American Wildlife Enforcement Officers Association's conference, Wolslegel's booth was one of the most visited by wildlife-enforcement officers and game wardens hoping to stay one step ahead of tech-savvy poachers.

"When I began my career over 20 years ago, all you had to do was dust the snow off the decoy and it was ready to go," said association President Lawrence Hergenroeder.

Wolslegel fell into his job 30 years ago, when he took what he believed would be a temporary gig with a taxidermist in Wisconsin while he tried to become a firefighter. Soon after, local wildlife officers made a novel request, asking if he and his boss could make a decoy. Positive reviews led to more requests from law enforcement. Eventually, Wolslegel's boss encouraged him to start his own business.

"So I did, and I never fought a fire," Wolslegel said. "I don't regret a second of it."

To make his decoys, Wolslegel applies the skin of a dead animal to a mold made out of polyurethane. He affixes glass eyes and plastic ears. The circuitry to make the decoys move comes from parts for remote-controlled cars. With some AA batteries, officers can remotely operate the Bambi bots.

"When we first started, it was as simple as a piece of fishing line that went from the ear to the tail," he said. "So when the ear would move, the tail would twitch."

As his products caught on, Wolslegel made modifications based on requests. Officers asked him to make a leg move. Then to make the ears twitch. Then to get the head to turn.

When an officer wanted a decoy that goes No. 2, Wolslegel figured out a system. "Its tail would lift up and it pooped out M&M's," he said. (Brown, of course.)

More recently, officers have asked for help against poachers using thermal rifle scopes and thermal drones. "These guys said, 'Hey this is what the enemy is using. We gotta come up with something that we can fool 'em with,'" said Dave Tanger, a mechanical engineer who helped Wolslegel with the design.

It took them a year of trial and error to figure out a way to replicate an animal's body heat using heating pads and coils. Tanger was reluctant to provide detailed information about the mechanics, fearing it would tip off poachers and possible competitors. "I'll give you this much: It's electric," he said.

Wolslegel sells about 50 to 60 deer decoys and 10 or 20 turkey decoys a year. He also makes a few elk, moose, wolf and bear decoys. Prices range from $2,200 to $7,000, depending on the size of the fake animal and the complexity of its movements. The thermal deer will go for just under $6,000.

The taxidermist is already considering his next project: a decoy that emits a visible breath on a cold morning. He thinks a CO2 cartridge might do the trick.

Mark Kropa, law-enforcement supervisor for the northeast region of the Pennsylvania Game Commission, said his agency has purchased Wolslegel's deer, turkey and bear decoys. Next up: a fake coyote.