With the prairie provinces of Canada most likely off limits to most Americans this year, North Dakota is bracing for an onslaught of waterfowl hunters who have been crossing the border for decades.

"It could be a real zoo," said Al Afton, a hunter and wildlife ecologist who lives near Bemidji. "North Dakota will be shoulder to shoulder."

Afton, an adjunct professor of renewable natural resources at Louisiana State University, said the global coronavirus pandemic will lessen pressure and disturbance on ducks and geese as they begin their migration from arctic and sub-arctic breeding grounds. A decision is expected soon on whether to keep the international border closed to nonessential visitors past Aug. 21, but most people believe it will stay closed for months.

It's unclear what that means for waterfowlers hiding behind cattails in Minnesota and other places in the north-central flyways of the U.S. Part of the uncertainty stems from the lack of reliable data this year on the birds' breeding success. COVID-19 social distance restrictions kept many wildlife agencies in the U.S. and Canada from surveying habitat conditions and production of young.

"We don't have much quantified data," said Afton, who has hunted waterfowl in Canada every fall since 1973. "We don't know what the flight will look like."

In Saskatchewan and elsewhere in Canada, American duck hunters outnumber resident hunters. Of the 17,000 licensed waterfowl hunters in Saskatchewan in 2018, 54% were nonresidents.

The approaching drop-off in hunting pressure in Canada has prompted some U.S. hunters to speculate that the birds might linger in Manitoba and Saskatchewan longer than usual.

Afton said the lack of disturbance won't delay or prolong the migration of "calendar ducks" such as teal, wood ducks and pintails. They are typically the earliest ducks to reach United State skies and they take flight regardless of the food supply in Canada.

He said weather — like always — will be a major influence on the movement of other species. If mallards, bluebills, geese and other waterfowl can't feed because of snow and ice, they will travel. Even in times of normal hunting pressure, a good food supply will keep the birds in Canada, experts say.

"It's a good question, but I don't know if less hunting pressure will have an impact," Afton said.

On the other hand, with many hunters expected to be staged in North Dakota, the ducks and geese could backtrack temporarily into Canada if they get blasted, Afton said.

John Devney is senior vice president of Delta Waterfowl Foundation in Bismarck, N.D. He said he has received calls from hunters throughout the U.S. seeking advice on where to hunt in North Dakota as an alternative to Canada. South Dakota isn't an option for nonresidents unless they obtained a license through a lottery that's now closed.

"The outfitters in North Dakota are starting to get pretty filled," Devney said. He predicts that Minnesota also will see an increase in duck hunting this year. Minnesota's duck season opens Sept. 26. In North Dakota, nonresidents can hunt starting Oct. 3.

Devney said waterfowl hunters are optimistic by nature. One theory about the upcoming season that's already floating around anticipates that lots of "young and dumb" ducks normally shot in Canada will be ripe for the taking when they sail into the U.S.

But Devney said the Canadian harvest — even when aided by American hunters — has been greatly diminished by the loss of hunters. Canada just isn't shooting that many ducks anymore, he said.

"I don't think hunting pressure is materially affecting migration timing very much," Devney said. "Things definitely are going to be different this year, but it's a little bit hopeful to think the hunting will be better."

Mike Szymanski, migratory game bird management supervisor for North Dakota Game and Fish, said "it's a little bit concerning" that thousands of duck hunters who usually take trips to Canada will instead be looking to locate themselves near lakes and wetlands in North Dakota. Some of the groups will be larger than normal, looking for the kind of field hunts that happen on trips to Manitoba, Saskatchewan and Alberta.

"We're expecting to take kind of the brunt of it," Szymanski said. "We expect there to be quite a bit of competition for hunting spots."

Unlike Minnesota and other states, North Dakota completed waterfowl-related field work this spring. The surveys showed a good year of production with ample precipitation and standing water. Szymanski said the fall flight of North Dakota waterfowl is projected to be up 9% compared to a year ago. Drought conditions have crept into parts of central and western North Dakota, but brood surveys showed robust populations.

"It was definitely a good year for duck production," he said.

To the contrary, habitat conditions in Saskatchewan and Manitoba have been on the dry side, and waterfowl hatches further north may have been below average because of prolonged cold weather, especially on west Hudson Bay and on Southampton Island.