Snow that was deep enough for skiing, scouting, snowshoeing – and swearing – covered much of the upper Great Lakes states as we trudged out of March, but while wintery Aprils can plague North Woods white-tailed deer, they don’t faze ruffed grouse. That’s especially true if the grouse can bury themselves in snow overnight for protection from predators and cold temperatures. Ruffed grouse, after all, are the Eskimos of the bird world. But instead of building shelters from blocks of snow cut with saws and shovels, grouse simply dive head first into snow banks to end a flight, or stand atop the snow and shuffle and shimmy in place until submerged.Those entry techniques become difficult as snow melts, freezes and compacts, but as long as it’s 8 inches or deeper, grouse usually make it work. Still, they prefer light, deep and fluffy snow, which is seldom a problem during North Woods winters.
Pollen from the buds of poplar, birch and cherry often give grouse droppings a yellow tint. Otherwise, the droppings are dark.
My friends and I often find the grouse’s abandoned snow roosts in Ashland County while bowhunting deer from late November to early January, or when snowshoeing and scouting in February. No matter the roost’s construction, we always stop to investigate, maybe because bird architecture never loses its interest. Sometimes snow roosts are just softball-sized potholes with grouse tracks leading away. Other times they’re flanked by matching wingtips in the snow where grouse launched themselves from shallow caves. Still other snow roosts – called “kieppes” – link to a collapsed tunnel. A closer look at the tunnel’s far end usually reveals the bird’s entry point. Grouse burrow the horizontal tunnel in between for one to three yards before settling into their overnight roost. Biologists assume grouse dig these short tunnels to disguise their roosts from foxes, coyotes and bobcats, much as cottontails do when building snow tunnels to their burrows. That’s probably a safe assumption, but there’s no doubting the thermal protection of the roost itself.
A collapsed tunnel leads to a ruffed grouse’s abandoned snow roost in northern Wisconsin.
There’s been lots of research into the ruffed grouse’s “thermal energetics.” That’s the temperature where grouse must increase their metabolism and body heat to maintain proper functions. When must grouse start burning extra energy? Well, some experts say it’s 40 degrees and other say it’s 28 degrees. Either way, ruffed grouse are built for harsh winters, and that means surviving temperatures far colder than the 30s.
Scott Walter, the Wisconsin Department of Natural Resources’ upland ecologist, said when he was conducting research with students at UW-Richland Center before his WDNR days, he calculated that grouse roosting beneath snow burned 2.5 times less energy than those roosting above it. When lacking snow for their “igloos,” grouse roost in thick conifers (fir, pine, spruce or cedar) or in big red oaks holding leaves from the previous autumn. Roosting above ground, however, leaves grouse more vulnerable to raptors such as owls and hawks. And if they’re in the North Woods, they could fall to goshawks when these medium-sized raptors drift farther south in winter than usual. “Snow roosting might not be a big advantage on calm nights with temperatures in the 20s and 30s, but when it’s windy and below zero, snow provides great insulation,” Walter said.
A ruffed grouse eats buds from a white birch in the North Woods.
Dan Dessecker, director of conservation policy for the Ruffed Grouse Society, said studies of snow roosts found 40- to 50-degree temperature differences from outside air. Generally, grouse emerge from these roosts after dawn and before dusk to forage for buds – or catkins – on poplar, cherry and birch trees. However, at least one researcher found grouse will hunker in snow roosts a day or more during blizzards and severe cold snaps. Whether their stays are short or long, grouse aren’t shy about fouling their digs. Every grouse kieppe I’ve inspected held a pile of dark or yellowish droppings, depending on their diet. The yellow tint comes from pollens clinging to buds the grouse ate.
Make no mistake, though. Ruffed grouse aren’t defenseless against the elements. As cold weather approaches in autumn, their shins grow feathery leggings. At the same time their toes sprout hair-based appendages called “pectinations,” which grow to the side to keep them stable on ice while holding their 17- to 25-ounce bodies atop snow. When they’re roosting beneath the snow, however, grouse remain wary of predators and other intruders. Walter recalls crossing a snow-covered clearing in a southwestern Wisconsin wood one winter with a colleague, and seeing several craters pocking the smooth, white surface. Empty snow roosts, no doubt.
Ruffed grouse have no trouble roosting in trees during winter when the air is calm and temperatures hover in the 20s to 30s.
As they approached the clearing’s far side they saw grouse heads sprouting from the snow like gophers on watch. Milliseconds later, the birds exploded into flight as if from underground missile silos. “They took off in a big whir of wings, and were gone,” Walter said. “It was one of the most memorable things I’ve ever seen and heard.”