Brutal winter didn't knock out northern Wisconsin grouse
Ruffed grouse populations in Wisconsin have shown another slight decline this spring, but northern Wisconsin numbers were the exception, as they were up about 3 perent, according to a survey.
It seems the coldest winter on record in much of the north didn't knock out the grouse. In fact, it helped.
In regard to the slight increase in northern Wisconsin, Gary Zimmer, coordinating biologist for the Ruffed Grouse Society, points to winter 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 use tree buds as food during winter, so snow cover doesn't reduce food availability," Zimmer continued.
The wet spring is a negative factor, however.
"Weather conditions, especially during the brood rearing period in late May and early June, also play an important role in 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," he said.
Results from the spring survey help Department of Natural Resources biologists monitor the cyclic population trends of ruffed grouse.
"The index that Wisconsin uses to track ruffed grouse decreased 1 percent stattewide 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 rise and fall over a nine- to 11 year cycle. For decades, biologists have speculated why the numbers follow the cycle, but there has been no definitive answer.
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," Dhuey said.
Roadside surveys have been conducted by staff from the WDNR, 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. One of the primary spots for grouse, the central region, showed a 24 percent decline.
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 grouse need for cover has led to a lower ruffed grouse population there.
"Ruffed grouse are closely linked to young forest habitats that develop following disturbances, notably logging," 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," he said.