Barn swallows are federally protected under the Migratory Bird Treaty Act, so getting rid of them legally comes down to timing and prevention. You cannot remove a nest once a bird has started using it, even if the nest isn’t finished yet. The most effective approach is removing old nests and installing physical barriers before swallows return in spring, then interrupting any new construction attempts daily until the birds move on.
Why Timing Is Everything
Barn swallow breeding season runs from March through September. The birds migrate north from Central America each spring and look for familiar nesting spots, especially sheltered horizontal surfaces like eaves, rafters, porch ceilings, and the corners where a roof meets a wall. They strongly prefer to reuse old nests from previous years, which is why leaving last year’s nest in place practically guarantees they’ll come back.
The critical legal line is this: once a barn swallow starts spending time in a nest, even an incomplete one, it is illegal to remove that nest until the birds have left. Destroying an active nest is a federal crime. That means your window to act is between October and late February, before the birds arrive. If you miss that window, you’re limited to interrupting brand-new construction before any bird occupies it.
Remove Old Nests in Winter
Your first step, ideally in fall or winter, is knocking down every old nest and scraping away all traces of mud. Barn swallows build cup-shaped nests from mud pellets, and even a small mud remnant signals “nest site” to returning birds. Use a putty knife or scraper to clean the surface completely. If you leave fragments behind, swallows will patch and rebuild on top of them far faster than starting from scratch.
Install Physical Barriers
Physical barriers are the single most reliable deterrent, and the U.S. Fish and Wildlife Service recommends them as a permanent solution. You have several options depending on the area you need to protect.
Netting or Wire Mesh
Plastic bird netting or poultry wire with a mesh size of about 3/4 inch works best, though 1-inch mesh has also been used successfully. The netting should be mounted from the outer edge of the eave down to the side of the building, creating a barrier that blocks access to the sheltered surface where swallows would attach a nest. Keep the netting taut so it doesn’t flap in the wind, which causes tangles and breakage at mounting points. A system of hooks and dowels makes it easy to install and remove seasonally if you prefer not to leave it up year-round.
Never use mist nets or any thin, flexible netting with loose pockets. These can trap and entangle swallows, which is both harmful and illegal.
Smooth Surface Treatments
Barn swallows need a rough surface for their mud nests to grip. Coating potential nesting sites with slick materials prevents the mud from sticking. Options include sheets of plexiglass or smooth plastic (like coroplast), plastic sheeting, or silicon-based paint applied to the surface. These work especially well on beams, rafters, and ledges inside open structures like barns and carports.
Bird Spikes and Vinyl Strips
Bird spikes installed along ledges and beams prevent swallows from landing and building. For open entryways like barn doors or loading docks, overlapping vertical strips of vinyl plastic create a curtain that lets people and equipment pass through but discourages birds from flying in.
Interrupt New Nest Construction
If swallows have already arrived and you spot fresh mud appearing on a wall or beam, you can knock down the mud daily before any bird begins occupying the nest. This is legal as long as no bird is using the structure. Swallows are persistent, so you may need to do this every day for a week or two before they give up and choose another location. Consistency matters. Skipping even a couple of days can give the birds enough progress to start roosting in the nest, at which point you must stop.
Why Scare Tactics Rarely Work
Fake owls, reflective tape, hanging CDs, and other visual scare devices are a common first attempt. They’re also largely ineffective against barn swallows. These birds nest in close proximity to humans by nature, on porches, in garages, under bridges. They habituate quickly to stationary objects and aren’t easily spooked by the kind of activity that would drive away less human-tolerant species. Physical exclusion is far more effective than trying to frighten them away.
Cleaning Up Droppings Safely
Barn swallow droppings aren’t just unsightly. They can harbor fungi and bacteria that cause respiratory infections, including histoplasmosis and cryptococcosis. These infections are uncommon but can be serious, particularly for young children, older adults, and anyone with a weakened immune system. Histoplasmosis causes fever, chest pain, and a persistent dry cough. Cryptococcosis can lead to meningitis-like symptoms including severe headache and mental disturbances.
The key safety rule: do not sweep, vacuum, or dry-scrub accumulated droppings. This sends contaminated dust airborne, which is how infections spread. Instead, wet the droppings thoroughly first to keep dust down. Wear a dust mask or respirator and gloves. Bag the waste rather than hosing it into soil where it can continue to grow fungal spores. If a large accumulation has built up over several seasons, consider hiring a professional removal service.
What to Do If Nests Are Already Active
If you’re reading this in the middle of nesting season and birds are already established, your legal option is to wait. Barn swallows typically fledge their young about three weeks after hatching, and the entire cycle from egg-laying to departure takes roughly six weeks. Some pairs raise two broods per season, which can extend the timeline into late summer. Once all birds have left and the nest is empty, remove it immediately and install barriers before the next spring. The silver lining is that barn swallows eat enormous quantities of mosquitoes, flies, and other insects, so a single season of coexistence has tangible benefits for your property even if the mess is frustrating.