The ruffed grouse (Bonasa umbellus) is a non-migratory, ground-dwelling game bird. It is known for the explosive flushes it makes when approached too closely as well as for the low drumming sound that the male produces in the spring.
Commonly known as the partridge, it is one of two members of the grouse family found in Vermont. The ruffed grouse can be found throughout most of the state, unlike the spruce grouse, which is very rare.
Habitat consisting of early succession tree species, such as aspen and paper birch, is most preferred by ruffed grouse. Superior grouse habitat will have the following characteristics:
- Three age classes of forest, zero to ten years, ten to 25 years, and more than 25 years, all located within a single home range. The location where the three age classes intersect is called an activity center.
- Seasonal food sources close to thick, woody cover.
- Patches of softwood cover to provide thermal protection during Vermont's stressful winter season. This type of cover is especially important when snow roosting is not possible due to lack of snow or a hard icy crust on the snow.
Ruffed Grouse need cover to protect them from predators during breeding, brooding, and winter roosting. Breeding cover consists of 15 to 25 year old hardwood stands that contain a few fallen trees (at least eight inches in diameter) and large stones or rock walls to be used as drumming sites. These drumming sites must have overhead cover, such as low branches or shrubs, to protect the birds from avian predators, and low horizontal cover, such as brush, to protect them from ground predators.
Nest sites are often found in open hardwood stands at the base of trees or in cut over areas just under the edge of slash piles. These sites offer protection from at least one direction, reducing nest vulnerability.
Brood cover is typically found in brushy areas or seedling/sapling stands. Lowland areas with a mixture of young hardwoods or alders provide excellent brooding habitat. The edge of fields or other open spaces also offer excellent brood habitat. These areas have abundant herbaceous vegetation and high insect populations. Both conditions are important to meet the high-energy demands of young birds.
When snow depths are sufficient, grouse prefer to use snow roosts for protection from severe cold and predators. They will plunge full-flight into a snow bank and bury themselves.
Winter roosting habitat is also available in dense vegetation, deciduous saplings, or softwoods that provide suitable cover and insulation. Under most winter conditions, hardwood stands are preferred because the birds are less vulnerable to surprise attacks by predators. However, softwood stands can be very important to grouse survival in Vermont. During cold periods when snow cover is lacking, the birds cannot dive into snow roosts and must seek out softwoods for protective cover.
The annual home range sizes of ruffed grouse vary from six to forty acres depending on habitat quality and the season. Male grouse ranges are smaller (six to ten acres) than those of females. Hens with broods of chicks range an even greater area in order to meet the specific food requirements of her brood.
The male and female interact only during the breeding season, which is in April. They have an elaborate courtship ritual that involves the male drumming, strutting, and even fighting with other males in competition for the female.
The male will select a drumming site, usually a log or rock wall, which is above ground level and provides a good view but is also well protected from predators. Here he will puff up his "ruff," or neck feathers and fan his tail in a grand display. He will also beat his wings rapidly, starting slowly at first and then increasing, to create a resounding thumping noise that penetrates the forest attracting resident female grouse and advertising its territory to other males.
Once they have mated, the female is left to nest and incubate the young. She will scratch out a depression at the base of a tree or under a bush, which will serve as the nest. It is often lined with dry grass or leaves and concealed for protection. The female's coloration will also help to camouflage her while nesting. The female will then lay nine to 14 eggs and will begin a 23-day incubation period. The eggs are a pinkish-buff color, either plain or spotted with dull brown.
In late May or early June, the young grouse, or chicks, hatch. The brood immediately leaves the nest in search of protein-rich foods, consuming large quantities of insects. After ten to 12 days, the chicks fledge, or learn to fly and, by six weeks, will have well-developed plumage that looks very much like the adult's.
By August, the brood size may have decreased considerably due to cold, rainy weather or other factors. In fall, the grouse begin to disperse and single or pairs will wander off to find new territory. This generally occurs more with younger birds than older ones, which often remain in their current habitat for the winter.
Coniferous forests are important for grouse because they provide excellent winter cover. Ruffed grouse will also use snow roosts during periods of heavy snow.
Grouse eat a wide variety of plants, but primarily forage on grasses and insects during spring and summer. Other foods include the leaves, fruits, and seeds of aspen, blackberries, raspberries, elderberries, wild grapes, apples, clover, and wintergreen. In the fall, beechnuts and acorns are primary sources of energy-rich fat, which the birds need to build up in preparation for winter. When these fruits are no longer available, grouse feed on the buds and catkins of mature aspen, birches, and hop hornbeam.
Aspen is widely recognized as a key tree species in ruffed grouse management. Buds of mature male aspen trees serve as a major winter food source, and young stands of aspen provide the necessary dense cover. These stands should be given priority over other timber types when managing for grouse habitat, where applicable.
Since aspen sprout prolifically when cut, stands with only a minor component of aspen can usually convert to predominately aspen if clear-cut or burned during dormancy. Other forest types good for grouse include red maple- cedar swamps, mixed spruce-fir and hardwood, alder, and birch stands.
Given that the home range of a hen with a brood may approach 40 acres, managing an area of 40 acres is adequate. An area of this size also provides habitat for several male grouse groups. Beneficial forest management practices for grouse can also be accomplished on areas smaller than 40 acres.
Once an area to be managed for grouse has been identified (preferably one that includes some amount of aspen), the area is divided into stands of five acres or less. Every ten years, treatment is rotated on one quarter of the stands as described below in a checkerboard pattern. The stands with the oldest trees are treated first.
Within each stand of five acres or less do the following:
- Prune apple and fruit producing trees and release them by cutting adjacent trees that are crowding them.
- Retain small patches of softwood trees (1/4 to 1/2 acre in size) for winter cover.
- Maintain rock walls and/or several large logs as drumming sites after the stand has been treated.
- Provide openings with herbaceous vegetation on ten% of the area being managed (four acres of a 40-acre management area). Keep livestock out or limit to fall pasturing.
- Create openings by seeding log landings and roads with a clover mix, and maintain them by periodically mowing.
- Maintain oaks, hop hornbeam, or beech as good sources of fall food, as long as they do not total more than 25% of the area.
During the winter, clear-cut the remainder of each stand being treated.
If the wood lot has not been managed before and consists of older aspen trees (more than 40 years of age), the management activities need to be accelerated.
Treat half the stands of five acres or less as prescribed above and follow with a second treatment of the remaining half of the area in ten years. Throughout the process, maintain groups of older aspen for winter food supplies.
Stands without an aspen component can also be managed for ruffed grouse. These stands are managed using the same techniques as aspen stands, but instead of treating areas of five acres or less every ten years, treat them every 15 years. Aspen and apple trees could also be planted if none are available. Other good forest types include red maple-cedar swamps, mixed spruce-fir/hardwood, alder, and birch.
The abundance of Ruffed Grouse often fluctuates from year to year. This seems to occur throughout the grouse's range. Their population also varies regionally, seemingly in an eight to ten year cycle, but the reasons for this are yet unknown. In Vermont, the Ruffed Grouse is a year round resident and is fairly common throughout the state in mixed or deciduous forests.