Many birds do indeed consume eggshells. This behavior is a natural and beneficial part of their diet, particularly for their health and during specific life stages. Understanding why birds seek out eggshells reveals a fascinating aspect of avian nutrition and adaptation.
The Nutritional Imperative
Birds consume eggshells primarily because they are a concentrated source of calcium. Calcium is a fundamental mineral for various biological processes in birds, including nerve transmission, muscle movement, blood clotting, and the formation and maintenance of strong bones. For female birds, the demand for calcium dramatically increases during the breeding and egg-laying season.
An eggshell is composed almost entirely of calcium carbonate, with calcium making up about 40% of its mass. Producing strong eggshells requires a substantial amount of calcium, often scarce in a bird’s regular diet of seeds and insects. During egg formation, a female bird can deplete her body’s calcium reserves, leading to health issues like thin-shelled eggs, egg-binding, or weak bones. Consuming eggshells allows birds to quickly replenish these depleted calcium stores, helping them lay healthy eggs and support their own physiological needs.
Providing Eggshells for Backyard Birds
Offering eggshells to backyard birds can provide them with a valuable calcium supplement, especially during nesting season. Before providing eggshells, it is important to prepare them safely to prevent the transmission of bacteria like Salmonella. First, rinse the eggshells thoroughly with warm water to remove any remaining egg residue.
After rinsing, sterilize the shells by either baking them in an oven at 250 degrees Fahrenheit (approximately 120 degrees Celsius) for 10 to 15 minutes or boiling them for the same duration. This effectively kills bacteria and dries the shells. Once sterilized and cooled, crush the shells into small pieces, roughly the size of sunflower seeds, for easy consumption. These crushed eggshells can then be offered in a shallow dish, mixed with birdseed, or scattered on the ground near feeders.
Common Bird Species That Seek Eggshells
Many bird species will readily consume eggshells, particularly those with high calcium demands. Songbirds, such as finches, sparrows, robins, chickadees, and thrushes, are frequent visitors to eggshell offerings, especially in spring and summer during their breeding cycles. Jays are also known to seek out calcium sources, sometimes even chipping off house paint if it contains limestone. Ground-feeding birds and gamebirds like quail, pheasants, and wild turkeys also benefit from and consume eggshells. Even raptors, such as hawks and owls, may consume eggshells, though less frequently than other bird types.