Starlings are omnivores, eating both plants and animals. Insects are easy to digest, and high in energy, so when they are available, Starlings eat them. If insects are not available, such as in cold months, Starlings eat seeds and other plant materials. They are harder to digest, so the Starling's gizzard enlarges and its intestines grow longer to handle the extra work. When insects are available again, its internal organs shrink back to normal size.