A landmark study by Aelred D. Geis on bird food preferences was published in 1980 by the U.S. Fish and Wildlife Service. The information below is based on the results of that study and lists the food products in order of preference for each species.
American Goldfinch -- Sunflower kernels (pieces), Nyjer, and oil-type sunflower.
Blue Jay -- Whole peanut kernels followed by black and striped sunflower seeds.
Brown-headed Cowbird -- White proso millet, other colored millets and canary seed.
Cardinal -- Oil-type sunflower and striped sunflower.
Carolina Chickadee -- Oil-type sunflower followed by striped sunflower.
Dark-eyed Junco -- Red and while proso millet, followed by canary seed and fine cracked corn.
Common Grackle -- Hulled sunflower seeds and cracked corn.
Evening Grosbeak -- All of the sunflower types.
House Finch -- Oil-type sunflower, sunflower kernel pieces and striped sunflower.
House Sparrow -- White proso millet and other small seeds.
Mourning Dove -- Oil-type sunflower and white and red proso millets.
Purple Finch -- Oil-type sunflower and other sunflower types.
Red-bellied Woodpecker -- Not a consistent visitor to the feeders, but clear preference for sunflower seed.
Song Sparrow -- White proso millet, red millet and oil-type sunflower seeds.
Starling -- Occasional visitors to the feeders and preference for peanut hearts and hulled oats.
Tree Sparrow -- Red and white proso millets and fine cracked corn.
Tufted Titmouse -- Peanut kernels and all types of sunflower seeds.
White-crowned Sparrow -- Infrequent visitor but preferred oil-type sunflower seeds.
White-throated Sparrow -- Sunflower seeds of all types and white proso millet.
Source: Geis, Aelred D. 'Relative Attractiveness of Different Foods at Wild Bird Feeders'. U.S. Fish & Wildlife Service Special Scientific Report No. 233. 1980.