Feeding trials.showed that ruffed grouse (Bonasa umbellus) performed well on diets containing 20% Christmas hollyfem (Polystichum acrostichoides) or mountain laurel (Kalmia latifolia), but diets containing 40% of these forages resulted in lower protein and energy intake and the Christmas hollyfem diet caused a loss of body mass. Grouse were not able to maintain themselves solely on evergreen leaves. Glucuronide excretion was greatest for the 40% mountain laurel diet. Ornithine conjugate excretion was greatest for a diet with 40% deciduous leaves. Sulfate excretion did not vary among diets. Intake rate of leaves was an asymptotic function of bite size when the density of bites did not limit intake. Intake rate of leaves decreased at plants densities < 322 plants/m2. The maximum intake rate of leaves was 25% of the intake rate of aspen buds observed in wild grouse (Huempfuer and Tester 1988). Intake rate of raisins was an asymptotic function of bite size and was 20 times greater than the intake rate of leaves. Ruffed grouse in the Southeast must forage for> 100 min/day under ideal conditions to satisfy energy requirements. / Ph. D.

Three experiments with captive ruffed grouse (Bonasa umbellus) demonstrated that dietary metabolizable energy (ME) can be predicted from neutral detergent solubles, total phenols, and percent acorns of grouse diets. The weight of the fat attached to the gizzard was highly correlated with percent carcass fat in 82 grouse and was judged a useful index of body condition. Crop contents of 1005 grouse collected during fall and winter 1981-84 in Maine, New York, Wisconsin, Washington, Virginia, West Virginia, Indiana, Ohio, North Carolina, and Georgia were used to make regional comparisons of food habits and diet quality. The ME of crop contents was predicted from chemical composition. Evergreen leaves of woody plants were the most common late winter forages of grouse in southeastern states, whereas buds, twigs, and catkins were the most common late fall and winter forages in diets of grouse in northern states. Winter diets in the Southeast tended to have higher levels of predicted ME than diets in the North; however, southeastern diets tended to have higher levels of total phenols and lower levels of protein than typical northern diets. Evergreen leaf forages had higher levels of tannin phenols than buds, twigs, and catkins. Dietary ME appeared adequate in both the North and the Southeast, but low levels of protein and high levels of tannins may result in poorer quality winter diets along the southeastern edge of the range of the ruffed grouse. Acorns comprised 63% of the crop contents of 22 grouse collected in Virginia in March and April 1982, the spring following a year of high acorn production. Leaves and flowers of herbaceous forbs were the primary forages of 41 grouse collected in spring 1983 and 1984. Body fat levels were greater for females than males and declined from March to April. Fat declines appeared to be related to breeding activities. Evergreen leaves were the most abundant forages available to grouse in late winter on a study site in southwestern Virginia. Biomass of high quality herbaceous leaves-was insufficient to meet estimated energy requirements of grouse in late winter, indicating a need for a dietary shift to low quality evergreen leaves. / Ph. D.