Experts Urge Gardeners to Scatter Crushed Eggshells Around Their Bird Feeders: ‘It Helps Their...'

When laying eggs, female hummingbirds and several other birds exhaust a lot of their body’s calcium supply. This means they need a good calcium supplement to replenish their bones and build muscle. The hummingbird is not going to pour a glass of milk for herself. So when she visits your feeder, you must feed her with calcium-rich “crushed eggshells,” as Reddit user u/GypsyDarkEyes does.

In the summer of 1996, some scientists headed towards Lane County with cameras strapped to their shoulders to observe female Rufous hummingbirds. About 1.2 kilometres from the Pacific Ocean, a rock jutted out from the ground under a bridge. Perched on this rock, a female hummingbird was flicking her tongue into the soil. She repeatedly flicked and retracted her tongue to lick the soil, and after some time, flew away, according to a report by Searchable Ornithological Search Archive. Curious, the scientists collected the soil samples. Analysis revealed that the soil didn’t have any insects.

The scientists were puzzled because hummingbirds usually fulfill their carbohydrate supply from flower nectar and their protein supply from insects. This soil had none. Turned out, the mysterious ingredient was calcium. “I always put out a dish of crushed eggshells near my birdfeeder this time of year. Calcium is hard to come by in the natural world, and many birds raid the nests of others just to eat the shells. Birds like shiny things, so I reuse an aluminum pan with holes punched to let out the rain,” the Reddit user wrote in the post.

Eggshells host a luxurious bounty of potassium, phosphorus, calcium, magnesium, and soluble salts, which are good for the birds, especially females who have just laid eggs. “Chopped, cooked eggs contain many essential nutrients for birds, and even the crushed egg shells will provide calcium for nesting birds, plus the grit helps their digestion,” experts at Really Wild Bird Food explain. Plus, calcium is highly digestible. The hummingbirds, as mentioned in the above-mentioned report, were observed during the breeding season, which explains why they were licking the calcium-rich soils under the Oregon bridge. 

In other observations, hummingbirds were recorded eating powdery white wood ash, which, too, contains high quantities of calcium carbonate and calcium oxide. Not just hummingbirds, other birds too need the essential calcium supplement to boost their health. Arctic sandpipers eating brown lemming bones, turkeys eating snail shells, tree swallows eating mollusk shells, chickadees eating wood ashes, nestlings eating fish bones, and red cockaded woodpeckers caching bone fragments; these sightings illustrate why eggshells are an excellent food for your bird feeder. So, pass the milk and cookies.

 To begin with, rinse the eggshells with warm water and then either bake them in the oven at about 250 degrees for 10 minutes, Wild Bird Unlimited explains. “Baking or boiling the eggshells before putting them out for the birds is a crucial step because it kills bacteria such as salmonella,” the website says. Once the eggshells are sterilized, crush them up and blend the powdery mix in your bird food or toss them on the ground for the feathered friends to feast upon.