Fewer drums heard in state grouse survey
Grand Rapids, Minn. — Ruffed grouse populations in the state are still on their way down.
But that’s no surprise.
In the northeastern part of the state – core grouse range – drum counts fell from 1.1 drums per stop last year to 0.9 drums per stop. In the northwestern part of the state, they declined from 0.9 drums per stop to 0.7 drums per stop.
“The decrease was not unexpected because the ruffed grouse population is still in the declining phase of its 10-year cycle,” said Charlotte Roy, DNR grouse biologist. “Drum counts peaked most recently in 2009.”
Drum counts didn’t change significantly in the central hardwoods or southeastern parts of the state.
The DNR uses drum counts as an index of the statewide ruffed grouse population, which tends to rise and fall on a 10-year cycle. The survey involves driving along established routes throughout the state’s forested region and counting the number of male grouse heard drumming.
After peaking in 2009, statewide drum counts fell in 2010, increased slightly in 2011, and now have fallen two years in a row.
“The last time we entered the lower part of the cycle, we stayed there for a few years,” Roy said. “So I don’t think it’s at all surprising to see the counts lower this year.”
She noted, though, that the peak of drumming – around May 10 – was about two weeks later this year than in typical years due to the spring’s cold, snowy weather.
“The fact the peak of drumming was delayed (to that extent) was a little bit surprising,” Roy said. “Typically, we tend to think of them as a little more closely tied to the photoperiod.”
During years of low grouse abundance, biologists expect about 0.8 drums per stop; the number is 1.9 or higher during years of peak grouse abundance. While the number of adults in the population is an important factor in what hunters see in the fall, so, too, is those birds’ reproductive success.
Given that drumming occurred later this year, it’s likely nesting also occurred later – potentially after May’s rain and cold, which is detrimental to production.
“In a real typical year, the peak of the hatch is going to be that first and second week of June,” Roy said. “Because things were a little later this year, we might be pushed out a bit, which might get us outside (the rainy period).”
In an average fall, 115,000 hunters kill about 545,000 ruffed grouse in Minnesota. While hunter numbers and harvest levels tend to follow the trajectory of the 10-year cycle, that wasn’t the case during the recent peak.
Hunter numbers in 2006 and 2007, for example, were higher than the peak year of 2009. And there also were more grouse hunters afield in 2010 and 2011. The grouse kill also was higher in 2010 and 2011 – 465,576 and 401,280, respectively – than in 2009, when hunters killed 357,998 grouse.
Sharptail counts fall, too
In the northwestern part of the state – the core sharp-tailed grouse range – counts were similar to last year. But in the east-central region, they declined significantly.
This year’s statewide average was 9.2 grouse counted per dancing ground, which is in line with the average since 1980. Between then and now, annual counts have ranged from 13.6 to 7.
Officials believe sharptail populations have experienced long-term decline due to habitat deterioration.
The DNR is in the first of a two-year study examining sharp-tailed grouse habitat selection and evaluating the management activities – shearing and mowing, for example – occurring around their dancing sites.
Lindsey Shartell, DNR forest habitat assessment biologist, has radio-collared 19 hens this year in Aitkin and St. Louis counties.
So far, it doesn’t appear this spring’s cold and rain affected sharptail reproduction.
“At this point, we’re not seeing any signs of that,” Shartell said.