THERE is so much debate going over the mysterious drop in adult ruffed grouse numbers that the citizen-run Natural Resources Board (NRB) wants to close the grouse season early this year.

At issue is an unexpected 34% decline in spring drumming counts this year despite a 30% increase the previous year, which records going back to 1964 indicate has never happened when the population is growing and headed toward the next peak in the 10-year population cycle.

The board has instructed the Department of Natural Resources (DNR) to formulate an emergency rule that would close the Northern Zone grouse season on Nov. 30 instead of the Jan. 31, 2019, closure that is already printed in the small game regulations.

If the rule gets Gov. Scott Walker’s signature, it will go to the NRB for approval at its Aug. 8 meeting.

Dr. Frederick Prehn, a board member from Wausau, had initially proposed that the northern grouse season end when the pheasant season ends Jan. 6. DNR officials said coordinating the grouse closure with the pheasant closure would be consistent and easier on hunters.

But Mike Riggle, vice chair of the Conservation Congress, said his group asked the DNR to reduce the bag limit and eliminate the late season — generally defined as the period when snow covers the ground and bud-picking grouse move to the treetops for food.

That’s why Riggle suggested Nov. 30 at the board’s June meeting and scoffed at the idea of picking a date that was best for hunters as opposed to what was best for the resource.

The scribbler couldn’t agree more, as the founders of the Ruffed Grouse Society (RGS) have written numerous times about protecting grouse that survive to the start of winter.

Their take on the issue has been that any grouse that survives predation and hunting for most of the year, through spring, summer and fall, is a hardy bird that is needed for breeding and nesting the following spring.

Grouse, the fastest and most elusive upland game bird in Wisconsin, deserve better than to be blasted in the treetops as they dine on the only food they can readily find in winter.

However, it would be prejudicial not to mention that most studies show hunting has little impact on overall bird numbers. The experts say the quality of the young forest habitat and spring brood-rearing conditions have far greater impacts on the population cycle.

That’s why last summer’s population decline is so mysterious. It was cold and wet for sure, but it appears that adult birds were adversely affected as much as the recruitment of young birds.

It makes little sense that we had a 30% increase in drumming during the spring of 2017 and were expecting a great fall hunting season, and suddenly the bottom fell out. It was one of the most dismal grouse seasons in the last 30 years.

If you judge the population by spring drumming standards, the adult population plummeted to a 13-year low. We haven’t seen drumming activity that low since 2006.

Some are suggesting that the West Nile Virus (WNV) might have had something to do with the decline, seeing that it has been detected in some dead grouse in Michigan and Pennsylvania.

But that’s quite a stretch considering that there has never been a confirmed case of a grouse dying from WNV in Wisconsin. Not one.

Maybe we shouldn’t be surprised that a population cycle that is heavily impacted by weather is doing strange things these days. We’ve got this global warming thing going and our weather extremes, both hot and cold, seem to be on the rise.

As an example, grouse numbers have been trending away from the 10-year cycle in recent years. If you remember, the DNR declared 2009 as a peak year and then recanted two years later and had to call 2011 the peak after an unexpected explosion in the population.

An equally puzzling trend occurred in 2015, a year the DNR has labeled as the low point in the current cycle even though grouse numbers remained much higher than a normal low.

I recall that the 2015 hunting season was a banner year, in stark contrast to what you would expect during the low point of the cycle. That proves that even one great spring for brood production can have a significant impact on grouse numbers and hunting success.

“With this somewhat abbreviated low point in the population cycle in 2015, an increasing phase lasting several years is expected, so a decline in 2018 is not consistent with a typical population cycle,” said Mark Witecha, the DNR’s upland wildlife ecologist in Madison.

The only viable cause known today for this sudden drop in adult bird numbers is the cold and extremely wet conditions that prevailed from mid-May through July last year. Nobody has claimed any other detrimental condition occurred, such as an invasion of avian predators from Canada or proof of some rare parasite or disease.

This is a mystery that may never be solved, especially when the population decline occurred at a time when the managers of state and county forests were stepping up logging efforts that improve young forest habitat for grouse.

We continue to have young forest habitat problems in the Chequamegon-Nicolet National Forest, where the amount of aspen and young forest types are on a long-term decline in accordance with a 15-year plan that was finalized in 2004.

A shorter grouse season might save a few birds from being shot, but it will have little impact on the overall cycle. The biggest reason for doing so is protecting grouse from being shot from trees during winter. That’s more of an ethics issue than a biological issue.

Lowering the daily bag limit makes little sense because most hunters never get a limit. The limit has been five for many, many decades.

All we can really hope for is a great hatch of young birds this spring along with good brood survival, so we can reverse the current trend.