Ruffed grouse numbers down in Minnesota, Wisconsin; West Nile virus one suspected reason

Minnesota and Wisconsin ruffed grouse are in trouble, with significant population falloffs because of West Nile disease. Or they're not — and something else seemingly is affecting these birds, which are among the most commonly hunted fowl in each state.

Recall that spring 2017 drumming counts indicated major upswings were occurring in both states' grouse populations as they edged toward cyclical population highs.

"The grouse population is nearing its 10-year peak.'' Minnesota Department of Natural Resources (DNR) grouse project leader Charlotte Roy said after the agency's drumming counts a year ago recorded a 57 percent increase from 2016 to 2017.

But either the survey — which essentially is an index intended only to detect long-term trends — was mistaken or something happened to ruffed grouse between spring and fall, when hunters took to the woods. Multiple reports from the field indicated grouse not only weren't up 57 percent but perhaps were down significantly.

"I would call it my worst season ever,'' said Ted Dick, an avid grouse and woodcock hunter who is the Minnesota DNR forest game bird coordinator and acting forest habitat team leader, stationed in Grand Rapids. "And I've been here 40 years.''

Even more compelling indications of a possible ruffed grouse die-off were harvest results last October from the annual Ruffed Grouse Society (RGS) fundraising hunt near Grand Rapids.

The 124 grouse killed during the two-day event represented a 30 percent decline from 2016. Worrisome also was that the hunt's 2017 kill was 50 percent below its more-than-40-year average.

Ruffed grouse hunting in Wisconsin last fall unfolded similarly. Data indicate grouse hunters there spent more time in the woods in 2017 than in 2016 but killed 30 percent fewer grouse,

Continuing the bad news, drumming count surveys this spring showed declines in both Minnesota (29 percent down from 2017) and Wisconsin (34 percent.)

"[The] surveys indicate the peak occurred last year,'' Roy said in a news release last week announcing the 2018 drumming count results. "Grouse populations tend to rise and fall on a decadelong cycle and counts this year are pointing to the peak lasting only one year this cycle. This has occurred before, but it's always nice when the cycle stays high a little longer.''

Roy didn't mention in the release that a suspected culprit in the grouse disappearance is West Nile virus (WNV), which made its U.S. debut in New York in 1999.

WNV, which is carried by mosquitoes, has been a particularly effective killer of crows, jays and similar birds, and researchers in Pennsylvania and Michigan have found it in ruffed grouse. Pennsylvania wildlife officials, in fact, say WNV is a serious threat to its ruffed grouse, and in response they have shortened that state's grouse hunting season.

On June 11, Wisconsin DNR upland wildlife ecologist Mark Witecha wrote a lengthy memo to the state's Natural Resources Board, which had requested on May 23 a response from him to a recommendation made still earlier this spring by the Wisconsin Conservation Congress to shorten the state's grouse season.

"Multiple factors working individually, concurrently or interactively can impact grouse populations beyond the normal nine-to-11-year cycle,'' Witecha said. "These population drivers include habitat conditions, brood and nesting conditions, food availability, winter conditions and disease.

"West Nile virus has been cited as a potential source of mortality in grouse,'' Witecha continued. "WNV was first detected in Wisconsin in 2002. Recent research from Pennsylvania suggests that WNV has potentially impacted grouse populations in the northeastern U.S., specifically in areas of lower habitat quality, but it is important to note that comparisons between northeastern U.S. states and upper Great Lakes states should be done with caution.''

Though Witecha argued against shortening Wisconsin's grouse season this fall, the Natural Resources board voted June 27 to do just that, ending the season Nov. 30 across much of the state, instead of Jan. 31.

A final decision is expected next month.

But unlike Pennsylvania and Wisconsin, Minnesota is not considering shortening its grouse season. Biologists here don't believe an abbreviated season would save grouse because hunting is believed to have little, if any, effect on these birds statewide (localized populations can in certain instances be affected by hunting).

Also, Minnesota's ruffed grouse season concludes essentially at the end of December, not the end of January, as in Wisconsin. And gunning pressure in Minnesota in the last half of December is usually low because of cold and snow. Plus, Minnesota has more and better ruffed grouse habitat than Wisconsin, which suggests, according to studies completed in Pennsylvania, that WNV's adverse effects on ruffed grouse would be less severe here than in other states.

Finally, fewer Minnesota hunters go afield for grouse these days than in the past, which is another reason not to shorten Minnesota's season, wildlife officials say. While the state remains second only to Alaska in fishing participation per capita, and second to Wyoming in the percentage (34) of residents who hunt and fish, Minnesota ruffed grouse hunters declined by about a third to nearly 70,000 in the 20-year period ending in 2016.

Still, some wing shooters who tramp the woods within 60 miles of Bemidji and Grand Rapids this fall will be asked to help researchers determine whether WNV is affecting grouse here.

Participating hunters will submit grouse hearts, a few feathers and blood on filter strips for testing. More information is available from Dick at ted.dick@state.mn.us or by calling 218-395-0577. Sampling kits will be available on a first-come, first-served basis. The study is partly funded by RGS.