RUFFED GROUSE CONSUMPTION AND DETOXIFICATION OF EVERGREEN LEAVES

Puffed grouse (Bonasa umbellus) in the southeastern United States comm only eat evergreen leaves during winter. Despite their abundance, thes e leaves rarely make up >50% of the diet. We fed diets containing 20 a nd 40% mountain laurel (ML) (Kalmia latifolia) and Christmas hollyfern (CHF) (Polystichum acrostichoides) to captive ruffed grouse to determ ine the bird's ability to exist on these forages and to investigate de toxification of secondary plant compounds. Grouse consuming diets with 20% of test forages performed similar to grouse eating a control diet . Diets with 40% of the test forages caused reduced intake and birds c onsuming the CHF diet were unable to maintain body mass. Conjugate-bas ed detoxification systems were stimulated by both test forages, althou gh detoxification strategies varied between forages and levels of fora ge in the diet. Although grouse appear unable to exist solely on everg reen leaves, these forages probably contribute to ruffed grouse winter survival by remaining available during snow accumulation and by decre asing foraging times due to high intake rates.