cardinals eat seeds and other plant parts (they’ve been known to eat flowers like forsythia) most of the year, their diet shifts to more protein-rich insects during breeding season in the summer. When chicks hatch, their parents mostly feed them soft caterpillars.
You can make it easier on the birds by adding plenty of caterpillar host plants, such as dill, fennel, parsley, coneflowers, and milkweed, to your container plantings and garden beds. Caterpillars will munch a few leaves on the host plants, but cardinals will find them before any major damage happens. If you don’t want to add plants to your garden, the next best thing you can do is avoid using homestead that kill caterpillars; instead, think of these insect larvae as essential food for cardinal chicks and many other backyard birds.
See more at: Cardinal I can only imagine poster
