More info for the terms: association, avoidance, basal area, cover, density, hardwood, litter, mast, mesic, selection, shrub, shrubs, tree
High stem density of the shrub-small tree layer is likely the most important characteristic of ruffed grouse cover [27,32,63,192]. A dense shrub layer protects ruffed grouse from avian predators [32,192] and may also provide cover during inclement weather [27]. In quaking aspen and quaking aspen-conifer stands in southeastern Idaho, drumming, summer, and autumn locations occurred where the density of small stems was higher than that of random samples (P<0.05) [180]. In southeastern Idaho, ruffed grouse selected areas with the highest shrub densities in spring [179]. A minimum density of 2,000 stems/acre [32,63] at least 5 feet (1.5 m) tall [32] has been recommended, and a review notes that cover is optimal in stands with about 6,000 to 8,000 stems/acre [24]. Areas with trees and shrubs at least 3 feet (1 m) tall occurring at densities of 6,000 to 25,000/acre provide excellent cover in hardwood stands (Kurzejeski and others 1987, Laubhab 1987, and Stoll and others 1979 cited in [192]). In aspen stands in Minnesota, ruffed grouse were positively associated with shrub density and shrub species richness [163]. In contrast, ruffed grouse were negatively associated with shrub species richness in quaking aspen-mixedwoods of Alberta [161].
A dense shrub layer also shades out groundlayer plants, making for high visibility at ground level. Increased visibility at ground level might increase detectability of approaching predators and allow for easier movement [192]. Gullion [63] suggests that the best aspen cover has a 50- to 60-foot (15-18 m) visibility radius at ground level. However, there is neither documentation of habitats with groundlayer vegetation too dense for ruffed grouse [33] nor any study specifically investigating the impact of groundlayer visibility on habitat selection, predation rates, pairing rates, or other indicators of habitat quality.
Habitat characteristics required at various life stages and different seasons are described below:
Drumming: Drumming habitat is similar to general cover required by ruffed grouse in that it has high shrub and/or small tree densities and high groundlayer visibility [33,156,192]. In western Washington, drumming logs had a visibility radius of 51 feet (15.5 m). On this site, drumming occurred in April before new vegetation reduced visibility [158]. Logs used for drumming provide good visibility at ground level [192]. Some overhead cover is apparently required on many sites [29,156], and topography is variable.
Shrub densities are high on drumming sites. According to a review, understory stem densities on drumming sites range from about 3,000 to 5,000/ha in Alberta and Ontario to 30,000 to 33,000 in the Great Lake states [156]. In northern Wisconsin, high shrub density was the most important factor influencing drumming site selection [33]. In southwestern Alberta, ruffed grouse occupancy and recruitment were significantly less and movement to secondary drumming logs was significantly greater in an area where stem density had been reduced compared to an untreated area [15]. Shrub density [185] and subcanopy cover [158] were greater at repeatedly used drumming sites than at infrequently used sites in Ohio [185] and in western Washington [158]. In Ohio, areas used nearly continuously by drumming ruffed grouse had 3 times as much brushland and heavily cut woodland (P≤0.05) as areas that were occupied by only one drumming male during the study [185]. In pine, aspen, and northern hardwood communities in northeastern Minnesota, drumming sites had greater stem density than unused sites [213]. Cover from 1 to 10 feet (0.3-3.0 m) around drumming logs in Grand Teton National Park in Wyoming was significantly (P≤0.044) greater than around random logs [20]. In southeastern Idaho, drumming sites had more small stems than other sites selected by ruffed grouse in spring [180]. In western North Carolina, midstory density and vertical vegetation density were greater (P<0.05) at drumming logs than at random logs, although the difference between woody understory density at drumming and random logs was not significant [164].
Dense shrubs without canopy cover may not provide suitable drumming habitat in some areas, including northern Wisconsin [33] and central Alberta (Rusch and Keith 1971 cited in [156]). Canopy cover was greater (P<0.05) at drumming sites than around random logs in northwestern Wyoming [20], greater than other sites selected in spring on a site in southeastern Idaho [180], and greater than sites 66 feet (20 m) away from drumming sites on a study area in Maine. On this site, canopy cover at drumming sites averaged 76.7%, while the average of paired sites 66 feet away was 64.6% [160]. On a site in western Washington, the average canopy cover at drumming sites was 62% [158]. Cover of conifers was greater (P<0.05) at drumming sites than other sites selected in spring in southeastern Idaho [180] and greater than at random logs in northwestern Wyoming [20]. Canopy height was greater at drumming logs than random logs [20]. In a review of quaking aspen forests of the West, drumming sites are described as having high overhead cover [29]. However, a review of early successional forests in the Central Hardwoods region states that canopy cover at drumming sites is variable and notes the occurrence of drumming in areas with little to no canopy cover [192]. In addition, it has been suggested that canopy cover more than about 60% could increase ruffed grouse mortality from raptors, especially if comprised of conifers (Gullion 1967b and Gullion 1970 cited in [156]).
Basal area was lower at drumming sites than unused sites in western Washington (P<0.001) [158] and northeastern Minnesota [213]. In contrast, there was no difference between the basal area of plots with drumming logs and those with random logs in western North Carolina [164].
Ruffed grouse drumming habitat often occurs in young stands. Males in Missouri [112] and Minnesota [215] selected young stands for drumming. In Pennsylvania, breeding males only occurred in areas that had been clearcut 3 times. The 3rd cut nearly doubled the amount of young shrubby vegetation compared to the area cut twice [209]. However, drumming has also been observed in mature forests [20,23,158] (see Stand ages).
Topography of drumming sites is generally not steep. In Maine the majority of drumming sites occurred in lowlands [160], while in western North Carolina over 85% of drumming logs occurred on ridgetops [164]. In the Central Hardwoods region, male ruffed grouse often selected drumming logs at the bases and tops of slopes <25° [192]. Drumming logs occur on fairly level ground [158,192] and along contours of slopes up to about 25° [24,192].
Drumming platform characteristics: Although logs are often used as drumming platforms, several other surfaces are also used including large rocks, roots [156,160,192], dirt mounds [156,192], stumps [160,192], and structures such as culverts [156] and rock walls [160,192]. In Maine these structures were used in over 50% of drumming sites. Average height of rock platforms was 44 inches (112 cm) above ground [160]. Since these features are common, they are not thought to limit the distribution of drumming ruffed grouse [156,214]. In a mosaic of primarily pine (P. resinosa and P. banksiana) and aspen (mainly P. tremuloides with some P. grandidentata) stands in Minnesota, male ruffed grouse used logs more than other structures for drumming. Despite agreeing that drumming structures are not typically limiting, Zimmerman and Gutierrez [214] suggest that "the paucity of logs in a particular area could reduce ruffed grouse abundance locally". A review notes that vegetation structure surrounding platforms influences ruffed grouse selection more than the characteristics of the platform [192].
There are usually 1 to 2 drumming logs per territory [156]. In western Washington, there was an average of 1.83 logs/territory [158]. Neighboring drumming sites are typically over 492 feet (150 m) apart, but drumming sites as close as 174 feet (53 m) have been observed [156]. Reviews note drumming logs are typically more than 6.6 feet (2 m) [156] to 10 feet (3 m) [192] in length. They may be much longer: In western Washington, length averaged 34.5 feet (10.5 m) [158] and in Maine, 30 feet (9 m) [160]. The longest drumming log reported in a review was 65.5 feet (20.0 m) [192]. Drumming logs are typically about 8 [156] to 16 inches (20-40 cm) in diameter [160,192]. However, diameter of drumming logs in western Washington averaged much bigger, 27 inches (69.5 cm) [158]. The drumming platform is often 17 to 22 inches (43-55 cm) from ground level [160,192]; although in western Washington, the average was higher, 24.8 inches (63 cm) [158]. In the Central Hardwoods region, the species of drumming logs reflected species availability (Stoll and others 1979 and Boag and Sumanik 1969 cited in [192]). Logs are typically decayed [20,192], but in at least some circumstances are still firm [20]. In Grand Teton National Park, drumming logs have less bark and fewer limbs than random logs (P≤0.003) [20]. Frequently-used logs in mixed mesophytic forest of Ohio were typically sound without bark, although significantly more had bark than infrequently-used logs (P<0.05) [185]. In western North Carolina, no significant differences were found between characteristics of drumming logs and random logs [164].
Nesting: Nesting habitat is the most variable of ruffed grouse habitats. It ranges from comparatively open [66] midseral (Bump and others 1947, Gullion 1969, and Maxson 1978a cited in [24]) or mature stands [66] comprised of pole-sized or larger trees [192] to stands "similar to drumming habitat" in western quaking aspen forests [29]. Nests in New York occurred in stands of any age but were often in midseral stands that were near edges or openings and standing water (Bump and others 1947 cited in [24]). Several reviews include high groundlayer visibility as a feature of nesting sites [29,156,192]. The Birds of North America [156] review also describes dense overstory cover, open understories, and trees from 2 to 8 inches (5-20 cm) DBH as characteristic of ruffed grouse nesting habitat. It notes that although nests may occur in wet shrubby areas, they rarely occur in dense vegetation [156]. Nests themselves are often placed at the base of a tree [156,192], stump, shrub, boulder [156], or log [192]. However, they sometimes occur in areas without an object nearby [156]. In Minnesota, most females selected nesting sites where they could fly from the nest directly to the male aspens they used for foraging (Barrett 1970, Kupa 1966, and Schladweiler 1968 cited in [66]).
Basal area has been associated with nest success and brood survival. In the central and southern Appalachians, nest success was positively related to basal area, coarse woody debris, and deciduous canopy cover and negatively related to ground cover and areas farther than 330 feet (100 m) from a road or opening [199] (see Brooding below). Based on predation on artificial ground nests in oak-hickory forests of Pennsylvania, Yahner and others [210] concluded that timber harvesting that leaves 23 to 46 m²/ha basal area would not negatively affect nesting success of ground-nesting galliformes, such as ruffed grouse or wild turkey. No relationship between habitat structure and nest success was observed in New York (Bump and others 1947 cited in [24]) or northern Lower Michigan, although this study was limited by small sample size [119].
Brooding: Relatively open areas with a moderate to dense ground layer and a well developed herbaceous component provide the cover and forage needed for ruffed grouse broods [24,156].
High herbaceous cover is a common component of brood habitat [29,60]. It contributes to availability of insect prey [192,197] and provides protection for broods [60,197]. Sites used by broods had greater ground cover than sites used by solitary birds in quaking aspen and mixed quaking aspen-conifer stands in southeastern Idaho (P<0.05) [180], random sites in Virginia and West Virginia (P<0.1) [78], and random sites in mixed-hardwood forests in western North Carolina (P<0.05) [103]. Broods 5 weeks old or less in Pennsylvania occurred on sites with greater herbaceous ground cover than would be expected based on availability. With each 10% increase in percentage ground cover, broods were 70% more likely to occur [197]. Herbaceous vegetation was significantly taller on sites used by broods than sites used by solitary birds in quaking aspen and mixed quaking aspen-conifer stands in southeastern Idaho (P<0.05) [180] and random sites in Virginia and West Virginia (P<0.1) [78]. Sites used by broods at night had more (P<0.001) concealing cover <3 feet (1 m) above ground than random sites in central Pennsylvania [196]. In mixed deciduous and conifer forests in Quebec, lateral obstruction from 0 to 6.6 feet (0-2 m) was greater (P<0.01) at brood sites than random locations, but percent of herbaceous ground cover less than 19.7 inches (50 cm) tall was not [54].
Small forest openings are often used by ruffed grouse broods, likely due to their association with greater herbaceous cover and availability of both plant and invertebrate food. Ruffed grouse broods occurred in sites closer to edges and openings than in random sites in aspen/scrub oak and mixed-oak communities in central Pennsylvania (P≤0.006) [166], and brood locations had greater percent open area than locations of solitary ruffed grouse in quaking aspen and mixed quaking aspen-conifer stands in southeastern Idaho (P<0.05) [180]. Summer use of a right-of-way by ruffed grouse 2 years after clearing was more than 14 times the use of a control (≥8 years since cutting) and 124% to 400% the use before treatment. Increased food availability was suggested as a factor in the increase [40]. Clearing vegetation in oak-hickory forests of Pennsylvania also increased availability of plant and invertebrate food sources, which declined as the opening aged and became shaded [168]. In Pennsylvania, broods 5 weeks old or less occurred in landscapes containing higher proportions of roads than would be expected based on availability. Roads were typically gated or were old logging roads with well-developed herbaceous layers and either had a forest canopy or were adjacent to a canopy. Survival of broods increased as distance to roads decreased, with broods close to roads exhibiting daily survival rates of 0.962 and those far from roads having survival rates of 0.926. It should be noted that at the landscape scale, density of roads was negatively associated with brood survival. Every 1% increase in road density was associated with a 0.004 decline in daily brood survival rate [197]. Broods surviving 5 weeks from hatching used forest roads and the edges of maintained openings in mixed-hardwood forests in western North Carolina [103]. In mixed deciduous and conifer forests in Quebec, females with broods occurred closer to roads than random locations (P<0.018) [54]. Openings may provide more forage than closed-canopy sites due to increased light levels supporting more food species and greater fruiting [24], but they may pose a greater risk from predators [192].
Direct, positive relationships between ruffed grouse brood occurrence and forage availability have been found on some sites. Sites used by females with broods in the 3 weeks following hatching had more arthropods than random sites in Virginia and West Virginia (P=0.02) [78] and greater invertebrate density than random sites in mixed hardwood forests in western North Carolina (P<0.05) [103]. According to a review, broods are commonly associated with high shrub cover and an abundance of food plants [24].
A review notes that broods in aspen communities are associated with high stem densities [24]. In mixed-deciduous and conifer forests in Quebec, small stem (≥20 inches (50 cm) tall; <3.5 inches (9 cm) DBH) densities were greater (P<0.01) at brood sites than random sites [54]. In an oak, northern hardwood, and pin cherry-aspen forest mosaic in Pennsylvania [197] and in aspen/scrub oak and mixed-oak communities in Pennsylvania (P<0.001) [166], small (<3.2 inches (<8 cm) DBH) stem densities were greater at brood sites than what was generally available in the study area. In the study in the forest mosaic, an increase of 1,000 stems/ha was associated with about a 12% increase in the likelihood of broods using a site [197]. Although stem densities were higher in brood sites, areas of high stem density were of secondary importance to ground cover in Pennsylvania [197] and western North Carolina [103]. In Virginia and West Virginia, total woody stem densities were not different (P>0.1) between brood and random sites [78]. In southeastern Idaho, broods used locations with lower small (<2.8 inch (7 cm) DBH) stem densities than used by solitary ruffed grouse (P<0.05) [180]. In a mosaic of stands dominated by aspen or pin cherry, sweet birch (Betula lenta), red maple in central Pennsylvania, chick survival exhibited a weak negative (P=0.037) association with small (≤3.2 inches (≤8 cm) DBH) woody stem density [196].
Conditions required for brood cover and forage often occur in stands 10 [24,32,166,192] to 20 [54,103] years or younger but also occur in mature stands. In mixed-deciduous and conifer forests in Quebec, females with broods selected habitat based on stand age, showing a preference for 2- to 20-year-old stands and avoiding 60- to 100-year-old stands and old, uneven-aged stands. Females with broods also selected stands based on time-since-clearcutting, with 11- to 20-year-old clearcuts selected and partial cuts and uncut stands avoided (P<0.05) [54]. In North Carolina, brooding females selected 0- to 20-year-old mixed-oak forest [103]. In central Pennsylvania, females with broods avoided an area less than 2 years old and selected 10-year-old clearcuts [166]. In oak-hickory forest of Pennsylvania, 21 of 24 broods used 1- to 5-year-old clearings; after 7 growing seasons, white oak (Quercus alba) and scarlet oak (Q. coccinea) shaded out understory vegetation, so food plants and fruiting declined and broods used these areas less frequently [168]. Broods used 20- to 50-year old hardwood stands in Iowa (Porath and Vohs 1972 cited in [24]), intermediate and mature aspen in northern portions of the ruffed grouse's range [156,183], and greater than 80-year-old mixed hardwoods in North Carolina. Selection of mature forests in North Carolina is likely due to canopy gaps contributing to early-successional habitat structure [103].
In some areas, broods are associated with lowlands, such as those dominated by alder. Greater use of mesic lowlands by broods compared to adults has been noted in several reviews [24,156], including those focusing on the Central Hardwood [192] and western regions [29,183]. Broods used lowland alder habitat almost exclusively in a Wisconsin study area [39], and in Minnesota brood sites usually occurred in dense alder thickets [60].
Importance of overstory apparently varies with location. In a mosaic of stands dominated by aspen or pin cherry, sweet birch, and red maple in central Pennsylvania, nocturnal brood habitat had greater deciduous cover than random sites (P<0.001) [196]. Broods on sites in Virginia and West Virginia used sites with more than 70% canopy cover, which was more than that of random sites [78]. Sites used by broods in western North Carolina had 75% canopy cover [103]. In contrast, ruffed grouse broods in quaking aspen communities in the western United States may use stands with more open canopies than those used by ruffed grouse broods elsewhere [29]. Broods in quaking aspen and mixed quaking aspen-conifer stands in southeastern Idaho used sites with less deciduous cover than that of locations used by solitary ruffed grouse (P<0.05) [180].
In a mosaic of stands dominated by aspen or pin cherry, sweet birch, and red maple in central Pennsylvania, nocturnal brood habitat had more coarse woody debris than random sites (P<0.048) [196].
Foraging: Foraging habitat varies based on season and ruffed grouse life stage. The types of forage eaten at different times of year give a general idea of the foraging habitat use (see Temporal and spatial variation in the diet). For instance, areas with well-developed herbaceous vegetation and shrubs are often used in summer and may be important from fall to spring in southern [156,167,178] and central regions [186], including the temperate deciduous forests. Catkins, buds, and twigs of trees are used from fall to spring [24]. In quaking aspen stands in central Alberta, winter feeding sites had significantly higher tree densities (>4 inch (10 cm) DBH) than systematic-grid stations, drumming log locations, and sites where ruffed grouse were shot [38]. In fall and winter in southeastern Idaho, ruffed grouse may have selected sites with high overstory cover in order to forage on quaking aspen buds [179]. In Ontario, total canopy cover was greater on female ruffed grouse locations than random locations in winter [11]. See Forage quality for information on possible explanations for the importance of aspen in diets of ruffed grouse in northern areas and the forage value of other community types, and see Brooding for information on areas where broods forage.
During much of the year, foraging occurs in mature habitats. In aspen, foraging is typical in stands 25 years or older [24,32,38,60,63]. In central Alberta, the average age of 100 male quaking aspen that ruffed grouse used for feeding was 36 years [38]. According to a review, ruffed grouse use midseral hardwoods for foraging in northern mixed forests [24].
Roads likely provide foraging for adult ruffed grouse as well as for broods. Roads and trails were selected by female ruffed grouse on 10 sites in the Appalachian region. This selection was stronger in years with poor mast crops, suggesting that these areas provide alternate foraging areas when preferred food is scarce [205]. On a site in Tennessee, converted logging roads had the greatest biomass of arthropods of the sites investigated [88]. Roads were also selected by ruffed grouse in an oak-hickory forest of Rhode Island [43]; in North Carolina, they were selected by females year-round and by males from fall to spring [102]. The importance of roads as foraging habitat in these areas was not discussed.
Other communities that often provide foraging opportunities include old fields and mesic bottomlands. In the Central Hardwoods region, old fields provide diverse of fruiting shrubs [192]. On 10 Appalachian study sites, female home range size decreased with increasing amounts of mesic bottomland, possibly due to the occurrence of important forage species [206].
Winter cover: In winter, ruffed grouse may select for conifer habitats, while stem density of sites used in winter varies. Female ruffed grouse winter locations had greater coniferous cover at all layers (P<0.05) and higher coniferous stem density and basal area (≥3.5 inches (9 cm)) than random sites. This may be related to the use of conifers for cover in inclement weather [11]; see Winter roosting below. In quaking aspen and mixed quaking aspen-conifer stands in southeastern Idaho, ruffed grouse selected sites in winter with significantly (P<0.05) fewer small stems than those selected by drumming males or females with broods [180]. In contrast, stem densities were greater on winter roost sites than random sites on a Missouri study area [193] and on 3 oak-hickory sites in West Virginia [203]. In winter in Ontario, females selected stands greater than 56 feet (17 m) tall and avoided stands 5 to 13 feet (1.5-4 m) tall (P<0.001). Winter locations have also been associated with greater canopy cover than locations selected in other seasons (see Foraging).
Winter roosting: Ruffed grouse roost at night and during the day in inclement weather. According to reviews, roosts often occur on the ground and in deciduous or coniferous trees [24,156]. Conifers are often used in hot [24], cold [156], or wet [24,156] weather. Ruffed grouse often roost alone but may roost in groups in winter [156,203]. On 3 oak-hickory sites in West Virginia, inversions lowered temperatures in valley bottoms in the evenings and nights, so ruffed grouse roosted in bottomlands more during the day than at night [203]. Most information regarding ruffed grouse roosts was collected during winter.
When available, ruffed grouse often roost in burrows in light, soft snow [156]. These provide the best thermal cover. In northern Minnesota, temperatures 7 to 10 inches (18-25 cm) under the snow remain fairly constant (about 20 °F to 25 °F (-6.7 °C to -3.9 °C)), despite temperatures 6 inches (15 cm) above the snow as low as -42 °F (-41 °C) [61]. In a Missouri study area comprised of upland oak-hickory, mixed eastern redcedar-hardwoods, and bottomland hardwoods, ruffed grouse temperature stress and metabolic rate were lower in snow roosts than open areas, resulting in less heat loss and greater energy savings in both calm and breezy conditions. Of 6 roosts located when conditions were adequate for snow roosting, 5 occurred in the snow [193]. In mixed-deciduous and conifer forests in Ontario, 36.3% of roosts occurred in snow burrows. In a moderate wind, female ruffed grouse were more likely to roost in snow burrows than in trees or on the snow surface (P<0.05). In deciduous stands, snow burrows were used significantly (P<0.05) more often than other types of roosts. The proportion of snow burrowing was negatively correlated with air temperature (P=0.01) and positively correlated with depth of snow (P<0.05) in 1 year of a 2-year study [12]. For ruffed grouse to roost in snow, they need crust-free snow [61] at least 8 to 10 inches (20-25 cm) deep [61,193]. Snow burrows are also effective cover from predators [61].
Ruffed grouse also roost in trees, most often conifers, in the northern ([12], Bump and others 1947 cited in [24]), western [29], and Central Hardwoods regions [193], but tree roosts may be most important where snow conditions are rarely adequate for burrowing [24,193]. Although snow provided better thermal cover, snow was rarely adequate for roosting on a site in Missouri. Eastern redcedar roosts, either on the ground near or in the tree, provided better thermal cover than open sites or deciduous stands. Eastern redcedar roosts were selected (P<0.05) by ruffed grouse and used for 86.8% of roosts. On this site, deciduous stands were avoided for roosting [193]. In contrast, on 3 oak-hickory sites in West Virginia, evergreens were not selected for winter roosting, and many roosting sites occurred on the ground in oak litter. Possible explanations for this trend included superior thermal protection provided by oak litter, evergreens species available on the site being inferior to evergreens typically used, conifers occurring in bottoms where inversions create cool temperatures, and/or avoidance of predators in evergreen habitats. Evergreens included conifers, mountain-laurel, and rhododendrons [203]. In winter in a mixed forest in Ontario, 41.2% of female ruffed grouse roosts occurred in trees. In calm conditions, female ruffed grouse were more likely to roost in trees than in snow burrows or on the snow surface (P<0.05). In uneven-aged and 21- to 60-year old stands, roosts were significantly (P<0.05) more likely to occur in trees than in snow burrows or on the snow surface. Proportion of tree roosting was positively correlated with temperature (P=0.001). Tree roosts represented 41.2% of roosts when conditions were adequate for snow burrowing. Despite snow burrowing resulting in the best energy conservation, it may not allow for regular feeding activities. This may have influenced the substantial use of tree roosts on this site, where ruffed grouse are able to move discreetly from coniferous cover to foods in deciduous vegetation [12]. Gullion [63] suggests that in northern Minnesota, conifers provide no benefit and reduce the quality of ruffed grouse habitat (see Plant associations used as habitat). According to a review, conifers probably have greater value for roosting in northern mixed forests than in boreal forests [24].
In some circumstances ruffed grouse roost on the ground. In winter in a mixed forest in Ontario, 22.4% of female ruffed grouse roosts were on the surface of the snow (22.4%). On cloudy days, however, ruffed grouse were significantly less likely to roost on the snow than in the snow or in trees (P≤0.05) [12]. On 3 oak-hickory sites in West Virginia, 55% of winter roosts were on the ground in nest-like depressions in oak litter up to 12 inches (30 cm) deep. Ground roosting was less common when it was raining and more common when it was snowing, suggesting that the leaf litter provided good thermal cover when dry. One ruffed grouse in this study burrowed into the leaf litter, completely covering itself [203].