If there aren’t enough snails around to consume, the birds’ eggshells may be too calcium-poor and brittle to survive the weight of a brooding adult. The snails depend on calcium-rich soil to build their own shells. Acid rain can reduce the calcium content in soils, severely reducing snail populations, and subsequently the reproductive success of birds.
Gardeners sometimes kill off the snails in their yards to protect their plants. They may be able to provide an alternative calcium source to wild birds, in the form of crushed chicken eggshells.
Watercolor, ink, and gel pen on paper. 6”x6”.