By Kate Crowley
As we began a hike with our Brazilian friends, Deise and Ricardo, I told them about the birds known as Ruffed Grouse that live in our woods and scare the daylights out of me every time I’m skiing our trails and they suddenly erupt into flight. I call them ‘heart-attack’ birds. It’s hard to communicate that level of surprise, if you’ve never experienced it. And it doesn’t matter how often it happens; from year to year, it always catches me off-guard.
This winter, when I have been able to ski, I have only had a couple of grouse make themselves known in this shocking manner. Ruffed Grouse, sometimes (mistakenly) called partridge are the most popular game bird in our state. Annual hunter harvest averages more than 500,000 birds, but that is an average because these birds, like some other animals, have a cyclic population dynamic. About every ten years their population will reach a peak in numbers and then gradually drop to the lowest numbers. Based on that cycle and recent population surveys, the Ruffed Grouse are now coming out of the low part of the cycle and moving up towards the next peak.
Surprisingly, researchers have found that the grouse population swings mirror that of the snowshoe hare. Studies show that when snowshoe hare numbers are up, the predator numbers (raptors and fox) also increase. This takes pressure off of the grouse so their numbers go up, but once the predators have taken the hare population down, they turn their attention to the grouse.
As we returned down Walters Rd. on our walk, Deise noticed something moving under the jack pines to our right. She said, “Is that one of those birds?” And sure enough, it was a Ruffed Grouse, trying to silently (for a change) escape our attention. It stopped beneath one of the pines and held perfectly still. Since it was a cloudy day and the bird was in the darker forest cover it was nearly impossible to see. If Deise hadn’t noticed the movement, we would have completely missed it.
This ability to blend in, to camouflage itself is critical to the bird’s survival. Ruffed Grouse come in two different colors – called morphs. There is the gray and the red. Typically the gray is more common to the northern regions and red to the south, although we can have both in Minnesota. Their mottled feathers allow them to blend in with the forest floor where they spend most of their time. These are not birds that fly unless there is a good reason, like getting up to the tops of the aspen trees to feed on the buds or to try to escape from a predator. Their heavy bodies and short wings are not designed for extended flight.
The wings of the male grouse though, do have another very important function and that is for ‘drumming’; a form of territorial display. This happens in both the fall and spring, as the males announce their presence to other males, as a warning, and to interested females seeking prospective mates. Grouse drumming is a sound I love. It begins slowly and gradually revs up until you can almost feel it in your chest. I have always thought it sounded like an old tractor engine getting started. This sound is created when the wings beat the air so forcefully that they create a vacuum and the resulting hollow thumping echo can carry up to a quarter of a mile away. Drumming is most often heard just before dawn and again later in the day.
Late March is the beginning of the courtship season, but the drumming behavior becomes much more intense as we move into mid and late April. An important feature of this courtship and territorial display is a ‘drumming’ log. While they can choose another object, old decaying logs are preferred. Usually the male stands on the end with the thickest diameter (seven to twenty five inches thick). Some males have just one special drumming log, while others will use move from one to another. Drumming has its risks too, since the sound can be heard by other creatures including those who consider grouse good eating. A wise grouse makes sure its drumming log is in the vicinity of low, thick, shrubbery where it can quickly find protection.
Ruffed Grouse are found across the northern tier of North America, with some in the lower elevations of the Appalachian and Rocky Mountains. Their core range in Minnesota is in the northeastern part of the state. Mixed forest with an abundance of aspen trees is critical to their survival, since the large buds are the major source of winter food. If these become scarce the birds will also eat the buds of birch, ironwood, apple and maple trees.
It’s hard to know if this has been a difficult winter for the grouse. There was never a great deal of soft snow to bury into, but we also had fewer subzero days. Winter is now on the wane and before long the Ruffed Grouse will be heard pounding out a reveille to wake the forest from its slumber.