European starlings, as their name suggests, were introduced to the Americas from Europe in the 1890s. According to the Washington Department of Fish and Wildlife, the starling population of the United States is estimated at 150 million. These birds are very aggressive at feeders and nest sites and have adapted well to living in close proximity with humans. If you don't take steps to prevent it, they're likely to take over the nest boxes and bird feeders you may have put out for other species.
Avoid attracting starlings in the first place by putting out foods, such as black sunflower seeds, that are difficult for them to eat. (Starlings have difficulty cracking the shells to get at the sunflower seeds).
Also, feeders that require birds to hang on the bottom of the feeder are a difficult obstacle for starlings.
Make the "neighborhood" unfriendly to starlings by depriving them of nearby nesting spots. Install bird netting underneath open rafters and place metal, wood, foam or other materials on ledges and over gutters at a 60-degree angle.3
Ensure that your nest boxes have entrance holes smaller than 1 1/2 inches across. This alone is usually enough to keep starlings out. If a nest box has an entry hole that's too large, or if flickers have enlarged the entry hole until it's big enough to let starlings in, add a new front to the box that has a hole of the appropriate size.4
Remove the perches on your bird feeders and nest boxes if present. Starlings need the perches, but most species do not; the only bird you're helping by providing a perch is the starling.5
Watch your nest box frequently during breeding season (anywhere from February to July). If you see signs that starlings are building a nest in the box, remove the material. You might also plug the entry hole for a few days, then reopen it once the starlings have moved on or lost interest.6
Take your nest boxes down every year or board over their entrance holes after breeding season. Don't put them back up again until you notice the native species you're hoping to attract have returned.