Though most of the FeederWatchers surveyed provide eggshells for birds throughout the year, some feed eggshells only during the spring and summer months, when birds are nesting, and a small percentage leave eggshells out only during winter. Most participants had birds visit their eggshell piles, though a few did not. I'll try again this spring to see if the birds will take them this time. I'll also keep better records. The survey strongly suggests that birds are opportunists, taking eggshells whenever and wherever they're available.
Many participants feed eggshells less deliberately.
Some FeederWatchers reported seeing birds remove eggshells from their compost piles. Later that day, a Blue-gray Gnatcatcher came twice to eat the shells. To date, survey participants have observed 68 different species of birds dining on eggshells. Species frequently reported to take eggshells include American Crows, House Finches, House Sparrows, European Starlings, Tufted Titmice, Black-capped Chickadees, Carolina Chickadees, Northern Cardinals, and a variety of sparrows. Eggshells were also taken by Red-bellied Woodpeckers, Summer Tanagers, Wild Turkeys, Pine Warblers, American Robins, and various species of orioles, towhees, and wrens.