The apparent metabolizable energy (AME) of ten different seeds, and three commercial feeds was determined for greater prairie-chickens (Tympanuchus cupido pinnatus) under simulated winter conditions. Seeds rated extremely poor potential energy sources for wintering greater prairie-chickens included buckbrush and Blackwell switchgrass (AME < 2055 kcal/kg DM), whereas Korean lespedeza, soybean, pearlmillet, corn, sorghum, and sunflower were rated excellent, in that order (AME > 3002 kcal/kg DM). The birds exhibited excellent AME's on several commercial diets (AME >2800 kcal/kg DM), but did not eat wheat grass-cuttings (Triticum sp.).