It's common to put out birdseed in winter to attract birds to your yard. I love looking out my back window at the chickadees and tufted titmice fluttering to and from the feeder, and the downy woodpeckers working diligently on the suet. But what most people don't realize is the proportion of insects that make up bird diets, especially when chicks are being raised. Insects are excellent sources of protein and vitamins, and are essential for most growing baby birds.
To support a healthy, diverse population of birds in your yard, it's important to provide high quality food for them all year. The best way you can do this is by growing native plants. To understand why, we need to know a little bit about the insects these birds are feeding on. Many of them are herbivores, feeding on plants. However, plants prefer not to be eaten, so they have developed many defenses against herbivory. Only insects who have evolved ways of evading these defenses can feed on those plants. Milkweed is an excellent example. While it's toxic to most insects, monarch caterpillars and several other insects have evolved to tolerate its chemical defenses. However, they are not adapted to the defenses of other plants, and therefore rely solely on milkweed for their survival. Most caterpillars, and many insect herbivores, have similar relationships with a few select host plants. |
So we can think of plants as producers of bird food. Rather than going to the feed store to stock up on sunflower seeds, all you need to do to feed birds during the breeding season is provide plants that will attract the insects they need. Introduced and invasive plants have herbivores in their natural home ranges, but often have very few or no herbivores where they are not native. Therefore, if your landscape is filled with non-native plants, it may look green and beautiful to you, but to a hungry bird it may be a desert.