MINNEAPOLIS (AP) - Visiting hunters have purchased fewer North Dakota waterfowl licenses this year, but officials are unsure if the trend will continue through the season.

"I think we're going to have a reduction, but the percentage is up in the air yet," said Paul Schadewald, a North Dakota Game and Fish Department administrator.

The state sold about 15,700 nonresident waterfowl licenses through last week, compared with about 20,000 during the same period last year.

North Dakota eventually sold 26,000 licenses last season, down from 30,000 in 2002. About half typically are sold to Minnesota residents.

Schadewald said the decline could be due to several factors, including frustration over nonresident hunting restrictions.

North Dakota imposed limits on when and where hunters from other states could pursue birds last year, prompting a federal lawsuit from Minnesota's attorney general.

Under the rules, visiting hunters may hunt for 14 straight days in North Dakota and may spend only seven days in each of two areas considered some of the state's best duck-hunting territory.

Nonresidents also are kept from North Dakota fields for the first week of duck season and are barred from hunting any game on land controlled by the Game and Fish Department from Oct. 9 to Oct. 15.

Minnesota's legal challenge argues that the nonresident hunting rules amount to illegal restrictions on business between states. A judge is considering the case.

Schadewald said other possible factors in the nonresident decline are more expensive licenses for waterfowl and pheasants, poor waterfowl conditions in some areas, and mild fall weather that hasn't pushed migrating ducks into the state yet.

Despite the lagging numbers, North Dakota officials are not panicking.

"It's early yet," Schadewald said. "Two weeks ago we thought it might be down 40 to 50 percent. But sales have really picked up recently."