Coaxing birds into a home garden or backyard can complete an outdoor space and provide hours of entertainment. And while the birds will naively thank you for any food you leave out, it's important to take some precautions to be sure not to interfere with their natural diet. For example, salt is not a natural part of wild birds' diets, and should therefore be avoided (no salted sunflower seeds). By following a few simple rules, you'll find yourself amid a healthy, happy flock in no time.
Do not put out salt (seeds, feed, or otherwise) of any kind. Salt is not a part of a bird's natural diet, and a sodium overload is not good for anyone, bird or human alike. Plenty of non-salted varieties of seeds, corn, suet and other tasty treats can be found at low costs in home and garden stores or supermarkets. Opt for seeds like sunflower; there are plenty of essential health benefits sans the salt: linoleic acid (an active fatty acid essential to good health), and tryptophan to ease the mind (yes, the stuff in turkey that makes you sleepy), Vitamin E, B complex, and minerals abound.
There's more to bird-feeding than seeds alone. Try fun and easy alternatives like popcorn (the unsalted, unbuttered, natural type), unsalted raisins, fresh fruit, homemade nectar (1 part sugar to 4 parts boiling water, cooled of course), or suet (available at most meat counters in delis). When putting out fresh fruit, and beef fat (suet), be practical: If it's hot out, don't let the food go bad -- pick it up before it spoils.
Birds can eat and will enjoy many human foods, but exercise caution. There are some toxic or potentially problematic foods to avoid, including avocados, chocolate, alcohol, iceberg lettuce, caffeine, carbonated beverages, seeds from fruit (depending on the fruit, some may be impossible for birds to properly digest or can cause choking), and more.
If you have doubts, err on the side of caution before putting out a potentially lethal meal.