June 10, 2014
MADISON - Ruffed grouse populations in Wisconsin have shown another slight decline this spring, according to a recent roadside ruffed grouse survey. Results from this survey help DNR biologists monitor the cyclic population trends of ruffed grouse in the state.
"The index that Wisconsin uses to track ruffed grouse decreased 1 percent between 2013 and 2014," said Brian Dhuey, DNR wildlife surveys coordinator. "This decrease is quite minor, and isn't unexpected at this point in the population cycle. Ruffed grouse populations are known to rise and fall over a nine to 11 year cycle. The last peak in Wisconsin's cycle occurred in 2011. We are headed to the low point in the cycle, which usually occurs in years ending in a 4, 5, or 6, so we are either at the low point or getting close; only time will tell."
Roadside surveys to monitor the number of breeding grouse have been conducted by staff from the Wisconsin Department of Natural Resources, U.S. Forest Service, tribal groups and numerous grouse enthusiasts and volunteers since 1964. Surveyors begin 30 minutes before sunrise and drive along established routes, making 10 stops at assigned points and listening for four minutes for the distinctive "thump, thump, thump" sound made by drumming male grouse.
The number of drums heard per stop in 2014 was down 1 percent statewide from the previous year. One of the primary regions for grouse in the state, the central region, showed a 24 percent drop in the number of drums heard per stop. A second primary region in northern Wisconsin showed a 3 percent increase.
According to Scott Walter, DNR upland wildlife ecologist, maturation of southern Wisconsin's forest community in recent decades and the resulting loss of dense, brushy areas that grouse need for cover has led to a lower ruffed grouse population.
"Ruffed grouse are closely linked to young forest habitats that develop following disturbances, notably logging activities," Walter said. "While we often focus as hunters on grouse numbers in a single year, it's important to remember that the long-term health of grouse and other early-successional wildlife is dependent upon the availability of the dense young cover they require. In Wisconsin, we need to ensure that enough timber harvests are occurring to meet the habitat needs of ruffed grouse and other early-successional dependent wildlife"
In regard to the slight increase in northern Wisconsin, Gary Zimmer, coordinating biologist for the Ruffed Grouse Society, points to this past winter's harsh weather.
"While cold temperatures and deep snow are generally hard on resident wildlife populations, ruffed grouse often thrive in winters like the one we just experienced," noted Zimmer. "Grouse roost under the snow, which can effectively serve as a blanket to hide them from predators' view and keep them warm even during very cold periods. It might be well below zero out in the open, but under even a few inches of snow the temperature might only be a few degrees below freezing. Grouse also utilize tree buds as food during winter, so snow cover doesn't reduce food availability."
Zimmer continues, "Weather conditions, especially during the brood rearing period in late May and early June, also play an important role in the fall ruffed grouse numbers. Newly-hatched grouse chicks are very sensitive to chilling, and warm, dry conditions allow high survival during the first few weeks of life."
"Grouse hunters are used to the cyclic nature of ruffed grouse populations, and know that during low periods grouse can still be found in the best cover. Hunters might have to work a bit harder to flush birds, but sunny October days with your dog in the north woods are tough to beat, and Wisconsin still has some of the best grouse hunting in the country," Zimmer said.
FOR MORE INFORMATION CONTACT: Scott Walter, upland wildlife ecologist, 608-267-7861 or Brian Dhuey, wildlife surveys coordinator, 608-221-6342