The vibrant red plumage of Northern Cardinals is always a welcome sight on a cold day. Northern Cardinals molt their feathers once per year, usually in August or September, after nesting and before winter. To regrow their bright red feathers, they must eat fruits (and insects) high in carotenoids, pigments that give many plants and animals their red, orange, and yellow colors. Cardinals get these pigments from the fruits of plants like honeysuckles, sumacs, and their favorite, wild grapes. In a study of molting Northern Cardinals in Ohio, fruit made up nearly 60% of the diet, with more than half of that being wild grapes. They are even capable of peeling grapes with their beak before eating the pulp and seeds. Though they also eat the fruits of many invasive plant species, like Multiflora Rose and Asiatic Bittersweet, they may actually help slow their spread: Northern Cardinals generally chew seeds up with their bill, so the seeds are not viable after they pass through the digestive system. Take a moment the next time you see a cardinal to observe how easily they crush through seeds with their massive, highly-adapted orange beaks, which also get their color from the carotenoids in their diet.
Backyard Bird of the Month is a feature by Maine Audubon created for the Maine Home Garden News, the newsletter of the University of Maine Cooperative Extension: Garden and Yard.
