When Minnesota liberalized its duck hunting regulations three years ago, officials expected hunters would kill more ducks.

And they have.

The changes, including opening the season earlier in September and increasing bag limits, have boosted the duck harvest. Hunters have averaged 750,000 ducks the past three years; they averaged 617,000 ducks yearly in the three years before 2011.

The increase has been notable especially for early migrants like wood ducks and blue-winged teal.

Hunters have bagged an average of 161,000 wood ducks yearly since 2011, including a near-record 184,000 in 2012. That's well above the long-term average of 109,000.

Some are asking: Are hunters now killing too many woodies?

State officials say there's no indication the increased harvest is hurting the wood duck population.

"I view it as 100 percent positive,'' Steve Cordts, Department of Natural Resources waterfowl specialist. "When we made the changes, we did it to increase opportunity, fully aware our duck harvest would increase. And that has happened. To date, there's no information that 180,000 is too many.''

Cordts acknowledged that the big increase hasn't gone unnoticed.

"Eyebrows have gone up, both internally and in some conservation groups,'' he said.

Count Brad Nylin among them. The executive director of the Minnesota Waterfowl Association supported the DNR's decision to start the duck season earlier but opposed increasing the daily wood duck bag limit, then two, to three.

"You see the numbers and say whoa, the three ducks could all be hens,'' Nylin said. "It is a concern. I'd be much more comfortable saying only one can be a hen.''

But Cordts said wood duck banding studies so far don't show a problem. The DNR is banding more wood ducks this year to boost the sample size.

Nylin said he'll be watching for the results.

"I'm OK with shooting three wood ducks if the data can support it won't hurt the population. But that has yet to be determined.''

Said Cordts: "The bottom line is the wood duck harvest the last three years wasn't much different from the 1970s and '80s.'' Minnesota hunters killed a record 185,000 wood ducks in 1984, when there were an estimated 134,000 duck hunters, compared to about 77,000 hunters last year. The U.S. Fish and Wildlife Service determined the wood duck harvest could be boosted nationwide and allowed states to increase the bag limits in 2008.

Minnesota didn't increase the bag limit until 2011. Cordts believes that probably accounts for 10 to 15 percent of the increased harvest. The rest is due to opening the season in September, before many wood ducks migrate south.

Early teal season?

Opening the duck season earlier — last year the opener was Sept. 21, the earliest in 68 years — also has boosted blue-winged teal harvest. Hunters averaged 83,000 blue-winged teal the past three years; the long-term average is 76,000.

The opener is the Saturday nearest Sept. 24, which this year is Sept. 27, six days later than last year. That could result in fewer birds for hunters.

About 84 percent of the teal harvest and 75 percent of the wood duck harvest occurs in the first nine days of the season.

There's less concern about impacts of increased harvest on the blue-winged teal population. The U.S. Fish and Wildlife Service spring survey estimated the continental population at 8.5 million, 75 percent above the long-term average.

To boost hunting opportunities, the service allowed states to offer early teal seasons this year. Minnesota was the only state in the Mississippi Flyway to pass, primarily because officials said they wanted to gauge hunter support first and because of concerns hunters would kill other duck species.

The DNR plans to survey duck hunters after the season to assess support or opposition. "There's a lot of resistance to a teal season here,'' Cordts said.

Meanwhile, Wisconsin, Iowa and Michigan are among the states that held early teal seasons. Officials in all three states conducted "spy blinds'' in which observers covertly watched hunters to assess how many non-teal were accidentally shot. Cordts said Minnesota officials will be looking at those results closely.

The state's lone teal-only season occurred in 1965, and officials said many other duck species were killed during that hunt.

Harvest didn't boost hunters

When Minnesota officials liberalized the duck hunting season regulations, providing more hunting opportunities with a longer season and earlier opener shooting hours and breaking the state into zones, they had hoped that hunter numbers would rise.

"They've pretty much remained the same,'' Cordts said. "But maybe if we hadn't made the changes we would have lost hunters.''

According to the DNR, hunter numbers averaged 78,000 over the past three years; they averaged 77,000 the previous three years.

Meanwhile, the season opens Saturday, and Cordts expects a harvest similar to last year, when hunters killed about 783,000 ducks. Unless cold weather sends wood ducks and teal south early.

Doug Smith • 612-673-7667