MINNEAPOLIS – With millions of acres of public land available for hunting in Minnesota and Wisconsin, it might seem odd that some outdoorsmen fight over who has the right to hunt on certain land.

But hunters’ shrinking access to privately owned property has made confrontations more likely, officials said.

Disputes rarely escalate into violence – as did the one that apparently led to a fatal shooting in Wisconsin on Sunday – but frustration is common, they say.

“It’s different than it was 20, 15 – even 10 years ago,” said Tom Conroy, spokesman for the Minnesota Department of Natural Resources. “It used to be you automatically had a place to hunt because Uncle Joe lived on the farm. Now…lots of us don’t know the landowners.”

A Wisconsin Department of Natural Resources warden, Mike Bartz, said there is plenty of public hunting land all over Wisconsin, but there are more hunters using it now. Meanwhile, private access land is shrinking.

Mr. Bartz said disputes on private land or staked-out territory on public land are not uncommon.

“I’m not even aware of any physical altercations over the years,” he said. “It’s usually a verbal exchange. And then 50 more ‘No Trespassing’ signs go up.”

Chai Vang, of St. Paul, is accused of fatally shooting six hunters and wounding two others in northwest Wisconsin on Sunday. Investigators say he wandered onto private property and then got into a confrontation with a hunting party.

A surviving hunter said Mr. Vang shot first after he was confronted on private land. Mr. Vang, a Hmong immigrant from Laos, has told authorities that a hunter fired at him first and that he was taunted with racial slurs.

About 650,000 deer-hunting licenses were sold in Wisconsin this year and 450,000 were sold in Minnesota – figures that have remained stable for years, officials said.

Wisconsin landowners can get a state tax break if they allow the public to use their woodlands. No such program exists in Minnesota, a DNR spokesman said.

Both states have at least 5 million acres of public hunting land and are buying more, but there are many millions of acres more in private hands.

Ryan Bronson, who directs hunter recruitment for the Minnesota DNR, said he ran into a dispute himself recently while on a goose hunt on private land near suburban Woodbury.

“The landowner gave special permission, and another group showed up and was upset. We had to wake up the landowner at 6 a.m. to come up with a solution,” he said.

The owner directed the groups to separate fields, and the problem was solved, Mr. Bronson said.

With access to private land tightening further, some officials say it might be time to consider broader approaches.

The so-called Open Fields bill introduced in Congress would provide financial incentives for landowners to open their land to hunters and anglers.

It would also provide federal money that states could use to administer their hunting-access programs, said a spokesman for Senator Conrad of North Dakota, the bill’s sponsor.

“We need to create some incentives and programs,” said Mr. Bartz, the Wisconsin warden. “But then again, our country was founded on private property rights, so it’s not easy.”

Mr. Vang, 36, is being held on $2.5 million bond. The Wisconsin state attorney general said charges were expected to be filed Monday at the earliest.

Killed were Robert Crotteau, 42, the owner of the land where the shooting happened; his son Joseph Crotteau, 20; Albert Laski, 43; Mark Roidt, 28; Jessica Willers, 27; and Denny Drew, 55, all from the Rice Lake area.