Northern grouse still cycle while Pennsylvania stays 25 percent down

STEP 1 · Cycle clock

Minnesota peaks still land near a 10-year spacing

The Minnesota Department of Natural Resources has run roadside drumming routes since 1949. Roy's 2025 report puts the statewide mean at 1.8 drums per stop. A 95% confidence interval runs from 1.6 to 2.2. For 2024 the same index was 2.3 and the interval was 1.9 to 2.6. Roy's 2025 survey puts average cycle length at 10 years. Peaks fall 8 to 11 years from one another. After several up years the drop is read as a possible 2024 peak that came slightly sooner than expected. The 2024 survey sets 1.3 drums per stop as the 2021 low. Earlier lows listed there are 1993 at 0.69, 2005 at 0.78 and 2013 at 0.86. Both reports give the 2009 peak and the 2017 peak as 2.1 drums per stop. The highest point estimate the survey reported in the past 50 years is the 2024 value. The interval still overlapped earlier peaks. The 2021 low stayed above the 1993, 2005 and 2013 lows.

STEP 2 · What counts

Fall harvest followed the drums less tightly after 2000

Minnesota routes use 10 stops set about 1 mile (1.6 km) apart. An observer at each stop listens for 4 minutes and tallies the drums heard. One drum is not always one bird. The spring index tracked fall harvest tightly before the early 2000s. Both reports say that bond later weakened. Post-count weather can still shrink the hatch. Roy says June 2024 was very wet and the thin snow of winter 2024 to 2025 may have played a part in the lower index. Our rule reads those drums as breeding-season loudness on the routes. Brood reports and October flushes come after. A statewide mean does not forecast one stand.

Region outranks the statewide mean. Northeast routes in 2025 averaged 2.0 drums per stop across 106 routes. Southeast routes averaged 0.7 drums per stop across 8 routes. Northwest routes averaged 2.3 drums per stop across 6 routes with an interval of 1.3 to 3.3. In 2024 the Northwest mean was 0.66 drums per stop on 8 routes. Roy called the rise unexpected. Our rule holds the Northwest out of trip plans until another spring repeats a result built on only six 2025 routes.

STEP 3 · Lake States

Wisconsin keeps its cycle while the highs sit lower

Roth's 2025 Wisconsin survey recorded 1.34 drums per stop on 90 routes. In 2024 the figure was 1.44 drums per stop on 91 routes. That decline equals 6.6%. The Northern priority area was 2.32 drums per stop across 52 routes and then 2.13 drums per stop across 51 routes. The decline there is 8.3%. Central routes on 24 routes moved from 0.41 up to 0.46 drums per stop. Driftless routes on 15 routes moved from 0.03 up to 0.09 drums per stop. The printed Driftless change is 250% and the report says to judge it by the small sample.

Wisconsin drumming still cycles across spans of 9 to 11 years. Cycle highs usually land in years ending 9, 0 or 1. Roth's report anticipates the next peak during 2029 to 2031. Since roadside routes began in 1964 a downward trend has left highs lower and the gain from low to high smaller. Roth and colleagues call changing land use and forest aging likely contributors to the flatter pattern. Roth and colleagues called that 57% rise in 2024 unexpected. The slight decline in 2025 still left drumming above the level they had anticipated. Survey crews ran no routes in 2020. Southeast routes stay off the survey where grouse are very scarce.

STEP 4 · Virus years

Pennsylvania flushes sit 25% under the pre-virus mean

Tyl's 2024 Pennsylvania report records 1.10 flushes of grouse per hour among 137 cooperators and 2,730 hours. Across 2002 through 2024 the mean flush rate is 1.09. Across 1965 through 2001 the mean is 1.45. Tyl states the mean for the virus era sits 25% lower. By late summer 2002 West Nile virus was detected across the state. From the 1965 to 1966 season onward the long-term average is 1.32 flushes per hour. The 2024 rate extended the run to twelve straight years below that average. Tyl calls a season high-abundance when the flush rate exceeds the long-term average by more than 10%. The last season at that level was 2001-02. Nine seasons have finished below 1 flush an hour. Widespread virus preceded all nine.

Young forest shrank over a longer span. Tyl cites the Forest Inventory and Analysis program. About 25% of timberland was seedling and sapling in 1955. The 2019 inventory put that share at 7%. Summer 2024 sightings were 18.03 grouse for each 100 observer days and 2.72 broods for each 100 days. The sample is 73 observers over 2,790 days. Brood encounters last ran that high in 2015. Grouse encounters last ran that high in 2016. Grouse sightings remained 50% below the long-term summer average. Brood sightings remained 51% below that average. North Zone hunters supplied 68% of sample hours and 86% of the harvest. The statewide rate leans on the north woods where birds are still being found.

Stauffer and colleagues compared 1980s and 2000s Pennsylvania breeding-bird atlas blocks with a 48-year flush series. Persistence and colonization ran lower where West Nile intensity ran higher. Both ran higher where forest and early successional habitat had increased. Flush rates fell across most regions once the virus was present. The 2018 Journal of Wildlife Management abstract calls the slopes imprecise and says habitat management may be insufficient to sustain populations while the virus is present. The work uses atlas maps together with flush trends.

Direct mortality evidence is the small pen trial. In Veterinary Pathology Nemeth and colleagues reported deaths within 8 days for 4 of 10 grouse that were naive and had been inoculated. The 6 alive on day 14 showed moderate heart lesions plus wider brain lesions. Three uninoculated birds kept beside them showed no infection. The Game Commission research summary describes a 2015 trial on chicks hatched from eggs taken in the wild and says 80% died or developed significant lesions among inoculated grouse. Those figures are one captive group and a poor proxy for how many wild birds die in summer. Corrected for hunter effort the same summary reports a 45% harvest decline across 2001 to 2005 and a 28% harvest decline across 2009 to 2014. Virus peaks sit in 2001 to 2004 and again in 2012 to 2014. Between peaks recovery looked stronger amid abundant habitat than amid fragmented habitat. The summary marks that habitat pattern as early. In the 2015-16 season the summary found wild grouse with antibodies in every Pennsylvania region. Those birds had lived until hunting season.

STEP 5 · Young stems

Stems younger than 20 years are the lever you hold

The Pennsylvania species page calls habitat the biggest factor behind state population size. The page treats forest under 20 years old as food, predator cover and weather shelter. Where this habitat is common the page says numbers rebound faster from West Nile losses. Virus mortality still hits these populations hard. A flushed grouse usually moves less than 100 yards.

Our early successional deer guide follows this aging problem through deer forage. Extension work summarized there shows abundant forage after a cut and a hard drop once crowns close. Grouse use the thick stem years in that same stretch. Our read is shaded hardwoods can feed deer on mast while holding no grouse. The guide never counts grouse. It shows the speed at which the thick stage ends.

STEP 6 · Three checks

Set the regional index against the stems you can see

Start from the regional index for your woods. In northeast Minnesota the 2025 core figure is 2.0 drums per stop. In northern Wisconsin it is 2.13 drums per stop. Southeast Minnesota on the edge is 0.7 drums per stop. The Driftless is 0.09 drums per stop. Edge swings in percent can rest on a tiny count.

A good covert is mostly stems of about 20 years or less. Density should hide the flush inside the short glide the Pennsylvania page describes. Watching the bird into open poles puts the covert outside that description. This sightline test is ours. No cited report timed a hunter's view.

Log hours and flushes like Pennsylvania cooperators. Their statewide rate in 2024 was 1.10 per hour. Your rate samples only the covers you chose. Young stems in a high drumming region that yield a strong rate fit these reports. Mature timber on the margin can post a high rate that still leaves the statewide picture unchanged.

Season dates and bag limits change from state to state. Read the current wildlife agency page for your state before the hunt.