Next squirrel season, Minnesota researchers will have the woods wired.

Every year, small-game hunters in this state bag hundreds of thousands of red, gray and fox squirrels. But lately, some hunters say, squirrels seem scarcer.

That was news to state wildlife biologists, who hadn’t given the state’s squirrel census much study.

“In general, squirrels are more or less like rabbits — they just keep reproducing,” said Ryan Tebo, a wildlife research biologist with the Minnesota Department of Natural Resources.

Many of the reports of squirrel depopulation came from hunters themselves, he said. “We’ve been hearing direct comment from hunters that they don’t think they’re seeing as many squirrels as they used to. They’re wondering if there’s an over-harvesting problem.”

So DNR researchers set out on a squirrel survey. But it was harder than it sounds, because if you want to count squirrels, you have to catch them first. It took months for Tebo and a team from the DNR’s Farmland Population and Research Group in Madelia, Minn., to wrangle 83 squirrels into radio collars before the mid-September start of small game hunting season.

“They are ferocious little things,” said Tebo, whose team tried to keep handling to a minimum to avoid stressing either the squirrels or the field researchers. Most squirrels were fitted with lightweight transmitters and zip collars and released within minutes. “They are not happy when they are in a trap, that’s for sure.”

It wasn’t easy to lure cagey squirrels into live trap boxes so they could be fitted with trackers.

“We had some pretty poor luck to begin with,” said Tebo, who spent weeks experimenting with squirrel bait. “We tried corn, sunflower seeds, peanut butter, apples — all with limited success.”

Until the team hit on the idea of loading the traps with walnuts — the same treats they’d seen the critters squirreling away all over the park. The squirrels came running.

Half the collared squirrels — 43 of them — lived in a Whitewater River Valley wildlife management area, where small-game hunting is permitted. The other 40 were collared on protected state park lands nearby.

Once the small game season opened in mid-September, researchers watched the transmission data to see how the hunting ground squirrels fared, compared to their protected neighbors in the state park. If a collar remained in one place for more than 24 hours, it went into “mortality mode,” which brought DNR staffers out with antennas and scanners, looking for evidence of the squirrel’s fate.

By the end of February, when the season ended, they could only find four active signals in the wildlife management area. Twenty of the collared squirrels were still transmitting in the state park.

That’s not enough data to determine whether squirrels are being over-hunted.

Researchers only found solid evidence of 13 of the 43 squirrels in the wildlife management area being brought down by hunters. Some of the missing transmitters might have malfunctioned, some of the squirrels might have gnawed through their collars or ended up as some coyote’s lunch. So this summer, the DNR team will return to repeat the experiment, this time hoping to collar at least 200 squirrels.

Meanwhile, when Tebo goes for a walk in Whitewater State Park, half an hour west of Winona, he still sees some of last year’s collared squirrels scampering around. He points them out to visiting students on field trips, giving them a glimpse of field research in action.

“It’s nice to see them being uninhibited by the collars,” he said. “They’re out there, just trolling through the woods, acting like a normal squirrel.”