Minnesota DNR survey sheds new light on spruce grouse population
Grand Rapids, Minn. — The first year of Minnesota DNR’s new spruce grouse survey shed new light on these northern birds that sometimes show up in the bags of ruffed grouse hunters.
A partnership of volunteers, as well as DNR, National Forest Service and tribal staff combined to map out a range for the birds as winter gave way to spring, culminating in Minnesota DNR publishing the results in a 17-page report earlier this month.
“We had no population information,” said Charlotte Roy, Minnesota DNR’s grouse project leader. “When we started, we weren’t quite sure of where the limits of distribution were.”
The survey broke the spruce grouse range down into three regions: a northwest region, or the northern Minnesota and Ontario Peatlands, a northeastern region composed of the Northern Superior Uplands, and a south-central region called the Northern Minnesota Drift and Lake Plains, which doesn’t extend much farther south than Lake Superior.
There were 40 volunteers that contributed, Roy said, noting that it was easier to find volunteers near cities such as Duluth and Two Harbors than in areas such as Red Lake Wildlife Management Area because of the distance volunteers would have to travel for the three-year commitment.
Still, Roy said she was probably most surprised by the level of interest in this lesser-known grouse species.
“There was such keen interest in them,” she said. “They are not a bird that many folks have at the forefront of their hunting or birding goals. I was surprised at the diversity of reasons that people were interested in them, from birders to naturalists to hunters. There were a lot of different types of people that came forward and were willing to dedicate time in participating in the survey.”
Volunteers were trained to conduct a survey on a route, looking for both spruce and ruffed grouse droppings, as well as taking observations regarding tree and cover types. The volunteers made a commitment that they would conduct the survey for three years. That means getting out on a predetermined spot, using a GPS unit, and walking a 100-meter perimeter around it at roughly the time when snow has begun to melt but is still present, making it easier to spot the droppings.
A pilot study determined that surveying grouse droppings was likely the best way to go about conducting the work and trying to build a population estimate and range of the birds. Previously, Wisconsin had used sound call survey, Roy said.
“The birds will respond to that in the spring,” she said. “We tried that but ultimately decided we weren’t getting enough detection to determine population trends.”
Of the three Upper Great Lakes States, only Minnesota has a hunting season for the birds, and as recently as 11 years ago, hunters killed an estimated 27,000 spruce grouse.
But Roy said harvest numbers are not a good way of determining a population estimate because those figures are more driven by the number of ruffed grouse hunters that may be in the woods on a given year.
And because spruce grouse are a northern bird, at the southern extreme of their range in Minnesota, scientists are predicting that the birds will altogether disappear from the Gopher State at some point, as the need for cover and for food shift into Canada.
“I would expect that the temperature would also play a role because of the thermal benefits of snow for roosting and things like that,” Roy said.
Nothing is imminent, but Roy said future decisions regarding the species could be made, but should be made using better science than is currently available.
“We want to make sure that we have good information so that we can manage in a sound way that will allow us to produce good decisions,” she said. “We want to make sure we have this type of information that, if and when the time comes that we have to make changes, we have the best information to do that,” she said.
The initial survey found spruce grouse at 88 sites, which represented 32 percent of the sites surveyed. More sign was found in the northwest portion of the survey region, followed by the northeast region. The survey will be conducted annually. Roy said that the major effort training the volunteers won’t be duplicated again this year, but that if there are people interested in volunteering, they could reach out to their area DNR wildlife office.
There is still work to be done on determining the extent of their range, Roy said.
“We occasionally get reports of birds much farther south than where we are surveying,” she said.