Cardinals are particularly fond of sunflower seeds, especially the black oil sunflower seeds, which are high in fat and provide essential energy for these birds. Fortified with vitamin A and D3 to aid growth, reproduction, feathering, and bone development. Calcium added for improved digestion, bone strength, and eggshell development. This 7-pound blend is formulated to support essential nutrition with added vitamin A, D3, and calcium, supporting bone strength, digestion, and feathering.