I recently had an experience while snowshoeing which I have always hoped to have, but which has escaped me during all these years of tromping through the woods. I was following the tracks of a Ruffed Grouse and all of a sudden it exploded out of the snow about two feet in front of me as it left its night time shelter. Now that we have over ten inches of fluffy snow, grouse can dive into the snow and spend the night in their self-made snow roosts. Finding a grouse’s snow roost is a relatively common experience; being startled by a grouse exiting one is not.
Diving head first into the snow, the grouse works its way anywhere from three to ten feet, creating a 4-inch-wide tunnel through the snow before it hollows out a small cavity and settles down for the night in its own little igloo. Up until recently, a hard crust prevented grouse from seeking shelter this winter in this manner. Had temperatures been very cold, many grouse would have suffered and even perished under these conditions. Fortunately, they can now roost in the snow, where temperatures are much warmer (as high as 32°F.), and rarely fall below 20°F. regardless of how cold it gets outside. Not only do these roosts hide the occupants from predators, but they provide an energy savings of 30 percent or more for grouse.
(Photo: Snow roost entrance hole (nearest the bottom of photo) where a grouse dove into the snow, and the exit hole (nearest top of photo), three feet from entrance hole, which a Ruffed Grouse created when it exploded out of its roost. If you look closely at the exit hole, you may be able to detect wing marks.)
Poplar (also called Aspen) buds are an important winter food source for wildlife, but for none as much as the Ruffed Grouse. During the course of a year, a Ruffed Grouse may feed from as many as 100 species of plants, but in the winter, species of poplar are by far its most important food source. In fact, the relationship between grouse and poplars is such that the range of the Ruffed Grouse is practically identical to the range of Trembling (also known as Quaking) Aspen (Populus tremuloides) and Big-tooth Aspen (Populus grandidentata).
Poplars are dioecious – the male and female flowers grow on separate trees. Although grouse will settle for any poplar bud, it is the male flower buds of Trembling Aspen trees which they prefer, due to the buds’ high amounts of proteins, fats and minerals. (Female buds are smaller and have less nutrients, oddly enough.) Ruffed Grouse seldom feed on a poplar tree that is less than 30 years old. Perhaps these older trees have more vigorous buds, or perhaps their branches are easier to perch on because they are larger. (Information source: Ruffed Grouse: Woodland Drummer by Michael Furtman)
A majority of male passerines, or perching birds (also called songbirds) claim territories and secure mates through song. With the help of a syrinx, or voice box, musical notes, some more complex than others, are created. There are species of birds in different orders that use other parts of their bodies for territorial and courtship displays, among them ruffed grouse (wings), American woodcock (wings) and Wilson’s snipe (tail).
Male ruffed grouse, also known as partridge, are aggressively territorial throughout their adult lives, defending roughly 6-10 acres of woodland which is usually shared with one or two hens. The male grouse claims his property by engaging in a “drumming” display during which he creates a sound reminiscent of a lawn mower starting up. This sound is made by the male beating his wings against the air to create a vacuum, as lightning does when it makes thunder. The drummer usually stands on a log, stone or mound of dirt roughly 10-12 inches above the ground when drumming and this substrate is called a “drumming log.” He does not strike the log to make the noise, he only uses the drumming log as a stage for his display.
Grouse occasionally drum in the summer and fall, but in the spring, drumming becomes more frequent and prolonged as the male advertises his location to hens seeking a mate. This phenomenon is heard but rarely seen by humans; Lang Elliott has captured both the sight and sound of a ruffed grouse drumming in this extraordinary video: http://langelliott.com/mary-holland/ruffed-grouse/ (Sound recording © Lang Elliott – langelliott.com)
Unlike much of the Northeast, central Vermont has only a few inches of snow on the ground. These conditions can affect all forms of predators and prey both negatively and positively, from exposed mice and voles to easily-satiated hawks and owls. In the case of Ruffed Grouse, which seek shelter on cold winter nights by diving into the snow, less than 10 inches of snow can spell disaster. In their snow caves they are hidden from view and well insulated (where it rarely drops below 20°F.). A lack of snow can be life-threatening for grouse if the temperature drops too low for too long. Unable to create a sheltered cavity in the snow, Ruffed Grouse bed down on top of it, often close to the base of a tree where there may be some shelter from the wind. Fortunately, most nights have not been extremely cold thus far this winter.
After the grouse departs in the morning, you often find scat where it bedded down. Grouse scat comes in two forms, one a dry, fibrous cylindrical pellet with a white-wash of uric acid at one end, and the other a softer, darker brown plop. The vast majority of a grouse’s diet (buds, twigs, leaves, catkins) goes directly through its digestive system and forms the dry, courser scat. Finer (and more nutritious) material such as the cambium layer of woody plants enters the caeca, two specialized pouches, before passing through the large intestine. The caeca contain bacteria which break down cellulose and produce the more digested, and therefore more liquefied, scat (see foreground in photo).
Those of us who feed birds are well aware of the hazards that windows and glass doors present to birds. The latest research shows that roughly 988 million birds are killed each year in the United States from hitting windows. Migratory birds and songbirds are the most common victims, but Ruffed Grouse, especially in the fall and winter, are very apt to collide with glass windows. (This phenomenon is not the same as the aggressive behavior towards glass that a bird’s reflection can promote, especially by males during the breeding season.)
Many of the grouse victims are first-year birds. Often, inexperienced young grouse, frightened by a predator, crash into buildings, trees or windows in a so-called “crazy-flight.” Hard, transparent glass is not something grouse recognize as a barrier, due to the reflections it creates. There are a number of things one can do to reduce the chances of this happening. Netting, decals, window film and tape hanging from the top of the window can help. One of many creative new products available are window panes that have external patterns that birds can see from the outside, but that are invisible from the inside. On a national level, legislation and bird-friendly buildings are gaining traction. For more window crash-prevention ideas, go to http://www.birdwatchingdaily.com/featured-stories/15-products-that-prevent-windows-strikes/. (Photo by Eve Bernhard)
Ruffed grouse typically have a short life span; few live to be three years old. By mid-August about 60 percent of the grouse hatched that year are lost to predators, weather extremes, disease, accidents (such as flying into windows) and hunters. Less than half of the surviving young survive through the winter to have a chance to breed in the spring, and less than half of those that survive long enough to breed make it to a second mating season. The hazards for a ruffed grouse are many, with predation at the top of the list.
Birds of prey, especially the goshawk and great horned owl, take many grouse, but terrestrial hunters such as foxes, coyotes, bobcats and fishers also take advantage of this plentiful food source. Along with hares, porcupines, squirrels, mice and voles, grouse are one of the fisher’s preferred foods. A fisher managed to capture a ruffed grouse in the pictured scene, leaving only tracks and a few tell-tale feathers to tell the story.
Common polypody (Polypodium virginianum), also called Rock Cap Fern, is a perennial plant found most often growing on rock surfaces usually in moist, shady woods. Being a fern, Common Polypody reproduces by spores. Structures that produce and contain spores (sporangia) are found on the undersides of the fertile frond leaflets. The sporangia form round clusters called sori. The sori of Common Polypody are orange-brown when mature and lack the protective covering (indusium) that some other fern species have. At this time of year, the mature spores are being dispersed by the wind.
The ability of Common Polypody to tolerate extreme desiccation (the leaves roll up when moisture isn’t as available, and resume their normal state when moist conditions return) means it is well adapted to the extreme moisture fluctuations of rock surfaces. Its evergreen fronds are consumed in the winter by Ruffed Grouse, Wild Turkey, and White-tailed Deer.