Ruffed grouse numbers are supposed to be on the upswing, but recent roadside surveys show the opposite. DNR biologists say the unexpected decline might be due to inclement weather at the time the counts were conducted.
Ruffed grouse population estimates are made by counting the number of "drums" heard along specified routes each spring. John Erb, a DNR wildlife research biologist in Grand Rapids, said the survey showed an 8 percent decline on routes in the northwest and a 17 percent decline in the northeast. North-central and central regions were stable. Southeastern Minnesota had an increase of 17 percent.
Grouse populations rise and fall in an approximate 10-year cycle. Drumming counts increased slightly last year, prompting hope that the cycle was on the upswing. This year, however, drumming counts were down 11 percent.
"It remains unclear," Erb said, "whether the apparent decrease in northern zones represents a real change in the population or whether it's just a result of sampling variability. Overall, winter conditions didn't appear detrimental to grouse and historic patterns suggest we should be on the increase in the cycle. It's possible the inclement spring weather may have delayed or reduced drumming intensity in many areas."
This uncertainty highlights the fact that drumming count surveys are a long-term trend indicator and that year-to-year changes should be interpreted with caution.
Sharptailed grouse numbers increased in the northwest and east-central parts of their range. Observers count sharptails on leks, where they gather for mating purposes. Surveyors counted 15 percent more birds in the east central range and 31 percent more in the northwest range.
Over the past 15 years, sharptail population fluctuations have mirrored the ruffed grouse population cycle. But sharptail numbers appear to have declined over the long term as a result of habitat deterioration.
Snowshoe hares also are counted on grouse survey routes. Their count declined this year by 37 percent, Erb said. Hare populations also fluctuate on an approximate 10-year cycle, and this year likely represents the beginning of a decline.
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