When Minnesota's duck season opens this fall, there likely will be something in the air besides wingbeats: change.

That's because the season might begin Sept. 24 -- the earliest in more than a half-century -- after the Legislature changed a law last week that for years forced Minnesota to delay the opener.

And shooting on opening day almost certainly will begin a half-hour before sunrise instead of 9 a.m. because of another law change.

The state also could be broken into north-south hunting zones, and the season split in the south -- opening for two days, then closing for a week, then reopening again -- while running continuously in the north for 60 days.

"All of those options are on the table," said Tom Landwehr, Department of Natural Resources commissioner. "I think it's fair to say we'll see a different structure this year."

The changes, intended to boost the chances for hunters to shoot ducks, are prompted by the loss of 40,000 state duck hunters over the past dozen years. Those falloffs follow decades-long wetland and upland losses, habitat degradations and hunter dissatisfaction over declining harvest.

Some Minnesota hunters have dropped out of the sport, while others have sought waterfowl in the Dakotas and Canada. Now the DNR is faced with a management conundrum: How to retain a critical mass of hunters while also trying to protect local duck populations.

Whether more birds in the bag will translate into more duck hunters remains to be seen.

"I think it will," said Brad Nylin, executive director of the Minnesota Waterfowl Association, who supports the earlier opener. Said John Devney of Delta Waterfowl: "It's a remarkably positive step in the right direction."

Regardless, the potential changes are historic. Minnesota duck hunters have never had hunting zones, and they haven't seen a split season in 18 years. While no decisions have been made, Landwehr said "there's a pretty good possibility" the opener will be Sept. 24 -- the earliest possible under federal guidelines.

That could give hunters a better crack at early migrating ducks -- such as wood ducks and blue-winged teal -- but it raises several other concerns. What about Youth Waterfowl Day, which, since it began 15 years ago, is held two weeks before the opener? It would fall on Sept. 10.

"That would be too early," Landwehr said. Even a week later might be too early, he said. Ducks likely wouldn't be fully fledged.

"If we went with a Sept. 24 opener, we'd have to talk about whether or not we'd have a youth hunt," Landwehr said. The DNR figures about 5,500 youths participate in the one-day hunt. Nylin said he would support a youth hunt on Sept. 17, a week before the regular opener.

Another issue: Whether opening the season that early would hurt the state's duck-breeding population, especially its coveted mallards.

"There certainly are some who think that's too early and it will have impact on local ducks," said Steve Cordts, DNR waterfowl specialist. But he believes the effects would be minimal.

"The bulk of the birds we'd shoot would be blue-winged teal," he said. Said Devney: "I just don't see any risk to duck populations. The positives far outweigh the negatives."

Dennis Simon, DNR wildlife chief, said the downsides of an earlier opener are fewer migrant ducks to hunt and resident birds becoming more vulnerable. The upside is that the early migrants would still be in the area and provide more hunting opportunities.

Simon sees more to the upside.

"Right now we have hunter satisfaction issues we need to deal with. Part of that can be addressed with more hunting opportunities. We also have habitat issues."

The Fish and Wildlife Service likely will give states more options for zones and splits this fall. For Minnesota, that could mean north, south and southeast zones along the Mississippi River. The north zone could open on Sept. 24 and run for 60 consecutive days. The south zones could open Sept. 24-25, then close for five days, then reopen for 58.

That would give southern hunters the opportunity to hunt ducks over Thanksgiving weekend -- something many of them want.

In fact, legislators passed a law in 2005 forcing the DNR to delay the opener until the Saturday nearest Oct. 1 just for that reason, Cordts said. That requirement was removed from the law last week by the Legislature.

Hunters will find out soon whether big changes are coming. Sept. 24 is only two months away, and Landwehr will have to make decisions within weeks so that rules can be adopted and waterfowl hunting regulations can be published on time.

One thing is certain: The last time the state duck opener was held earlier than Sept. 24, it was a far different world. In 1945, with soldiers just back from World War II, the 80-day duck season opened Sept. 20.

With a liberal 10-bird daily bag limit, hunters shot an incredible 2.6 million ducks -- the second-highest harvest ever.

Doug Smith • dsmith@startribune.com