The most effective way to keep swallows from nesting on your porch is to install physical barriers before nesting season begins and remove any traces of old nests. Timing matters more than anything else here, because once swallows lay eggs, their nests are federally protected and you cannot legally disturb them. Your best window for action is late fall through early spring, before the birds return.
Swallows Are Federally Protected
Before you do anything, you need to know the legal boundaries. All swallows are protected under the Migratory Bird Treaty Act of 1918. It is illegal to take, possess, or destroy swallows, their eggs, feathers, or active nests without a federal permit. Active nests (those containing eggs or chicks) cannot be touched or removed without a permit from the U.S. Fish and Wildlife Service, and the Service does not issue permits for general nuisance issues. Permit applications must demonstrate a compelling health or safety hazard.
Inactive, empty nests can be removed without a permit. In California, the state considers February 15 through September 1 to be nesting season, and completed nests during that window cannot be disturbed without federal authorization. Other states follow similar timelines. The practical takeaway: do your prevention work outside of nesting season, or at least before eggs appear.
Remove Old Nests Completely
Swallows are strongly attracted to old nests and even to faint remnants of dried mud left behind from previous years. If you’ve had swallows before, scraping off an old nest isn’t enough. You need to wash the area thoroughly so that all traces of mud are gone. A garden hose or pressure washer works well for this. Do it in fall after the birds have migrated south, or in winter well before they return.
Leaving even a small mud residue on your eaves is essentially a “vacancy” sign. Clean surfaces are far less appealing to returning birds.
Install Physical Barriers
Netting is the most reliable deterrent. Bird netting stretched across the underside of your porch eaves blocks swallows from reaching the wall-to-ceiling junction where they attach their mud nests. Secure the netting tightly so birds can’t slip behind it, and install it before nesting season starts. The netting should cover the entire area you want to protect, not just a small section, since swallows will simply build a few inches over.
For a cleaner look, some homeowners install angled boards or commercially sold “bird slope” products along the eave junction. These create a steep, slick surface (typically 45 degrees or more) that prevents mud from adhering. Sheet plastic or aluminum flashing attached at an angle along the wall-ceiling seam achieves the same effect. The goal is to eliminate the flat, textured surface that swallows need to anchor their nests.
Knock Down Nests During Construction
If swallows start building despite your efforts, you can legally remove nests that are still under construction, as long as there are no eggs or young inside. Use a long pole or hose the mud off daily. This part requires persistence. Cliff swallows in particular will rebuild their nests repeatedly for most of the breeding season, so you may need to knock nests down every day for weeks before the birds give up and choose a different location.
Check nests carefully before removing them. Swallows lay one egg per day until they have a clutch of three to four eggs. Once a single egg is present, the nest is legally off limits. If you’re going to use this approach, inspect and remove partial nests daily so you never fall behind.
Visual Deterrents Have Limits
Reflective tape, metallic streamers, and fake owls are commonly recommended, and they can help as a supplemental measure. Metallic streamers hung near eaves work best when they catch both sunlight and wind, spinning and flashing unpredictably. Some homeowners report success using them to keep swallows out of garages and away from light fixtures.
Fake predator decoys like plastic owls produce mixed results. Some birds avoid them initially, but many swallows learn to ignore stationary objects quickly. If you use visual deterrents, move them every few days to maintain the illusion of a real threat, and combine them with physical barriers rather than relying on them alone. Hanging bells alongside reflective items can add an auditory element, though sound deterrents on their own rarely solve the problem.
Redirect Swallows With Alternative Nesting Sites
Swallows eat enormous quantities of mosquitoes and other insects, so having them on your property (just not on your porch) is genuinely beneficial. You can install artificial nest cups or platforms on an outbuilding, barn, or sheltered structure away from your living space. Nest cups should be about 2 inches high and 5 inches in diameter, mounted with roughly 3 inches of clearance between the top of the cup and the ceiling above. Place them at least 6 feet off the ground and out of reach of cats and other predators.
If you’re mounting multiple cups, space them at least 5 feet apart with limited sight lines between them. Platforms (3 to 5 inches wide, 6 to 8 inches long) work as an alternative to cups. Position these structures near open foraging habitat like fields, pastures, or water, since swallows need to catch insects on the wing and prefer nesting close to where they hunt. A nesting kiosk placed 50 to 100 feet from your porch gives the birds a better option while keeping your seating area clean.
Timing Your Prevention Plan
The best approach combines several methods on a seasonal schedule. In fall, after swallows have migrated, remove all old nests and wash surfaces completely. Over winter, install netting, bird slope panels, or other physical barriers while you have plenty of time and no birds to worry about. In early spring, hang reflective deterrents as a secondary line of defense and set up alternative nesting structures if you want to keep swallows nearby.
If you missed the winter window and swallows have already arrived, your options narrow. You can still remove nests under construction daily, provided no eggs are present. But once eggs or chicks are in the nest, you’re legally required to leave it alone until the young have fledged and the nest is empty. At that point, remove the nest immediately, clean the surface, and install barriers so you’re ready for the following year.