The Rugged Ruffed Grouse: Heartbeat of our Winter Forests
Wintry weather can take a toll on year-round wildlife residents of mid-Atlantic and northeastern forests. For roughly one third of the year, regional forests offer little protective broadleaf cover from predators and the elements, have limited food sources, and are frequently inundated with snow. In response to these lean and harsh months, many woodland species go dormant or hibernate, but others rely on seasonal adaptations to make it through. The ruffed grouse (Bonasa umbellus) is one of these winter survivors; so honed for deep snow and brutally cold temperatures that its range is largely limited to forested regions of North America that receive heavy snowfall. Grouse are amazing species that have mastered life in northern forests but are facing declines in the eastern U.S. due to changes in land use and a maturing forest landscape. Without improved forest management, ruffed grouse will continue to decline no matter how superior they are at surviving through the winter.
Ruffed grouse are found throughout Canada and the northern U.S., with a population extending into the high elevation forests of the central and southern Appalachian Mountains. Emblems of forested landscapes, ruffed grouse are residents of densely-vegetated young forests for most of the year and require older forests at brief points in their life cycle. They build nests on open forest floors with mature tree canopies, often placing them against a tree so that the grouse can keep watch to the sides and front while still being covered from behind. Ideal nesting locations are near patches of forest younger than 10 years old, where grouse parents will lead their chicks to feast on high-protein insects in the herbaceous cover found in new forest growth. The chicks must grow quickly, so they almost exclusively eat invertebrates for protein before tapering into a mostly herbivorous diet. Adult grouse can digest high-cellulose plant material such as buds, twigs, and leaves in addition to fruit, and spend most of their adult lives in crowded stands of 15 to 20 year old trees, where this food is abundant and there is ample cover from predators like bobcats, hawks, and owls. Large logs or stumps within dense young forest cover are important “drumming” sites, stages from which males display to attract mates (more on this later).
In the early winter, ruffed grouse shift residency to more mature forests. When snow is sparse on the ground or too icy, they stay warm by roosting within the dense needles of conifers. Deep snow makes life much easier for ruffed grouse. Rather than avoiding the snow, they plunge into it head-first and build a tunnel. Within this refuge, they are safe from predators and can conserve energy spent on staying warm. These subnivean (under snow) hideouts typically stay between 20 and 32 degrees Fahrenheit, much warmer than air temperatures above the snow.
No matter what kind of cover, ruffed grouse have to emerge daily from their safe and warm roosts to eat; like most birds, they are not able to store much body fat. They must fly up to the treetops to eat buds, typically at dawn or dusk, leaving themselves exposed to aerial predators. So when they’re out in the open, they sprint to fill their crops (a storage pouch at the base of the esophagus) with as many buds as possible, gorging for only 20 to 30 minutes before diving back into the snow where they can safely digest the food throughout the day.
Grouse also grow special feathers around their beaks and legs to help insulate their bodies from the cold. They develop scales on their feet called pectinations that help them grip ice-covered branches and walk on top of the snow. In the spring, these seasonal scales and feathers fall off.
Hunting pressure for grouse is tightly regulated by state agencies, and while populations have largely been on the decline, the cause has predominantly been habitat loss and other factors, not overharvesting. In fact, passion for grouse hunting has contributed substantially to the sciences of ecology and wildlife management over the years. One of the first game laws in North America was passed in New York over three hundred years ago, in 1708, to set a closed season for Ruffed Grouse during part of the year. This early attempt at protecting game from overharvesting was hugely important. It set a precedent that grew to become the North American model of wildlife management; a crucial tenent of which is that hunting is important but populations must be managed for sustained use in perpetuity. Ruffed Grouse also played a large part in the development of the science of ecology. Their fascinating population cycles were heavily studied as early as the 1930s, and the body of research around the bird grew to inform our understanding of inter-species community and population dynamics (e.g. how prey abundances affect predator abundances, and vice versa).
Though perfectly camouflaged for the woods and often shy of humans in eastern forests, ruffed grouse are adept at making themselves known. Throughout the year males defend their territories and attract mates by drumming, a display where they rapidly beat their wings through the air, producing a deep thumping noise. This sound may travel long distances, much further than vocal singing will in dense woods, and can be felt in the listener’s chest cavity as much as it can be heard by ear. If you’ve never had the pleasure of hearing a grouse drum there are many videos and audio files online, but nothing can come close to experiencing it in person. The thumping beats start slow and rapidly get faster and faster, somewhat resembling a car engine slowly turning over and then starting. I have heard grouse drumming scores of times, and I am still always stricken with amazement and delight every time I am lucky enough to hear it again. It is a phenomenon that every nature enthusiast needs to hear in person. It is the heartbeat of healthy forests.
Sadly, ruffed grouse populations are declining across their range. Research has found that they are being set back substantially by West Nile Virus, but the predominant reason for their declines, like other denizens of young forests, is loss of habitat. Without dense stands of saplings and early-successional colonizers like aspen and birch, grouse lose their primary food sources and cover. Young forest habitat is relatively scarce on our modern landscape because of a reluctance for timber harvesting, human suppression of fire, and rapid invasions of disturbed forest by non-native plants that then suppress regeneration of native trees. A healthy forest landscape has a balanced ratio of patches that are young, middle-aged, and old, but forests in the east are overwhelmingly mature. A continued failure to return disturbances to our forest, whether they are prescribed fires or sustainable timber harvests, will only result in steeper population declines for the ruffed grouse and many other species that use early successional habitat. If we want to continue hearing the drumming heartbeat of our forested landscape, we need more balanced forest management.
To learn more about forest management and wildlife, visit forestsforthebay.org or contact Ryan Davis at firstname.lastname@example.org