Save your eggshells! Eggshells contain calcium and both young and adult birds need Calcium in their diet. If there is a lack of calcium in an adult birds diet, it can cause weak bones.
Use sterilized eggshells when feeding wild birds. This can be done by hard boiling the eggs and then peeling the shells or by baking eggshells in the oven or toaster oven at 200 degrees for 15 minutes. Crush and store in a jar until you are ready to add them to a homemade suet cake. You can also sprinkle eggshells in the backyard.