Smith: Regional study will examine the impact of West Nile Virus on ruffed grouse

Jim Hayett of Hartland enjoys the solitude and beauty of Wisconsin's Northwoods.

But in spring, he's fond of a certain kind of noise, too: the "thump, thump, thump, thump" of a drumming ruffed grouse.

Male grouse use their wings to make the loud, staccato sound in an effort to attract mates.

On two trips in April and May to his cabin near Park Falls, the silence has been deafening.

"Did not see or hear one (grouse)," Hayett said. "I'm really concerned."

He's not alone.

After positive spring drumming reports in 2017, ruffed grouse brood counts dropped last summer and hunters generally reported disappointing results in fall.

The trend was seen in Minnesota and Michigan, too.

In fact, at the 2017 Ruffed Grouse Society National Hunt in Grand Rapids, Minn., hunters set a record low for grouse harvest in the 36-year history of the event.

Notably, the hunter take was composed of 44% adult and 56% immature birds, markedly different from the long-term averages of 28% adult and 72% immature. 

So grouse recruitment — or survival of young — was poor in 2017.

And preliminary drumming counts for 2018 are not looking good. Of the four survey routes in Price County, three were down "considerably" and one was up slightly, according to Pat Beringer, Wisconsin Department of Natural Resources wildlife supervisor in Park Falls.

And all of this as grouse were supposed to be on the upswing in their well-documented population cycle.

"Something happened last summer," said Dan Dessecker of Rice Lake, who retired last year after working for 30 years at the Ruffed Grouse Society, including as the organization's director of conservation policy. "People like to point to wet or cold spring weather. but I don’t buy that for the entire region."

There is growing suspicion that the "something" was West Nile Virus.

The mosquito-borne disease has been found in Wisconsin since 2001 and is known to kill humans, horses and birds.

The impact of the virus on ruffed grouse in Wisconsin is still an open question largely because of a lack of sampling and research.

Only eight Wisconsin ruffed grouse have been tested for the disease (seven from 2002-'04, one in 2008); all were negative, according to the DNR.

But cases in humans last year were third-highest since the disease was discovered in Wisconsin. Through late December, 48 cases of West Nile Virus had been reported in humans in the state, resulting in four deaths, compared to 13 cases and two fatalities in 2016, according to data compiled by the state Department of Health Services.

An average of 17 cases per year were documented in Wisconsin from 2002-'16. The highs were 57 in 2012 and 52 in 2002.

So last year the number of human cases was about 2.5 times greater than the average since 2001.

Do the human trends translate to wildlife?

It's tough to say, according to Dessecker. But experience over the last two decades in North America has shown periods where the virus is "more active on the landscape."

"There are peaks of activity with it, where it kills a noticeable number of crows and jays in an area, for example," Dessecker said.

The disease is also fatal to ruffed grouse. 

Arguably the best research on West Nile Virus and ruffed grouse was conducted over the last decade in Pennsylvania.

Wildlife biologists with the Pennsylvania Game Commission collected wild grouse eggs in spring and exposed some of them to West Nile Virus. Hunter-killed grouse in Pennsylvania also were tested.

Two years of work helped frame the seriousness of the disease to grouse.

"WNV clearly kills ruffed grouse and as many as 80% of grouse exposed to the virus are killed outright or might have reduced survival," wrote Lisa Williams, game birds biologist for the commission, in a Sept. 2016 article in Game News.

Last year the Michigan Department of Natural Resources confirmed its first cases of West Nile Virus in ruffed grouse.

Five birds collected from August through October, including two found dead and three shot by hunters, were determined to be positive in testing at the Michigan DNR's Wildlife Disease Laboratory in Lansing.

Three of the positive grouse were from the Upper Peninsula, according to the MDNR.

It would not be surprising, then, for the mosquito-borne disease to also be found in grouse in northern Wisconsin.

That question likely will be answered definitively later this year.

On Tuesday the natural resource agencies in Michigan, Minnesota and Wisconsin announced a collaborative effort to study West Nile Virus and ruffed grouse.

It will include testing of grouse in each state. Hunters likely will be asked to provide samples, said Mark Witecha, upland game ecologist with the Wisconsin DNR.

Final details will be announced later this year.

Among the optimistic notes: West Nile Virus is not always fatal and animals can develop antibodies to the disease.

Thirteen percent of hunter-killed grouse in the Pennsylvania study showed antibodies.

In addition, animals in areas with the best habitat are best-suited to weathering the storms of the disease.

"Here in Wisconsin, we've got some of the best grouse habitat on the continent," Witecha said. "That bodes well for them, no matter what we find with West Nile Virus." 

Hayett and other avid grouse hunters will be anxiously awaiting the final Wisconsin drumming report, which typically is released in June, as well as the brood survey in August.

Until then, he'll have his eyes and ears trained for the native species that's been conspicuously absent this year in the woods near his cabin.

"Grouse are a big part of the reason I and many others love the Northwoods," Hayett said. "I sure hope this is just a blip and we still have a healthy grouse population."