Backyard birds come in all shapes and sizes. They eat nuts, seeds, berries, fruit, and insects. They welcome wintertime sprinklings of seeds in the snow. You may think that birds are light eaters, but it is quite the opposite. They are actually big eaters. Birds need plenty of food to produce the energy their bodies require to maintain a fast metabolism. This fast metabolic rate allows them to fly. They spend much of their time looking for, and eating, food. Seeds can be purchased at your local supermarkets. The ready-made mixes usually contain a lot of wheat, buckwheat, milo and other filler seeds and grains. Sunflower seeds are very easy to find. They come in two varieties, striped and smaller black oil seeds. Even though some of the smaller birds have trouble cracking the sunflower seed's shell, most birds love it! Plus it provides the birds with more fat and therefore more energy. If you make your own mix, check your feeder for leftovers and adjust the proportions to the birds' preferences.