Swallows build mud nests on houses every spring, typically tucking them under eaves, porches, or where a roof meets a wall. If you’ve found one on your home, you’re dealing with a situation that involves federal law, a specific seasonal timeline, and some practical tradeoffs worth understanding before you act.
What You’re Looking At
The two species most likely to nest on your house are barn swallows and cliff swallows. Barn swallows build open, cup-shaped nests made of mud pellets and grass, often on a ledge or beam under a porch or overhang. Cliff swallows build enclosed, gourd-shaped nests with a small entrance hole, and they tend to cluster in colonies, so you might see dozens packed together under an eave. Both species use mud as their primary building material, which they gather mouthful by mouthful from puddles and stream banks.
Swallows are strongly attracted to sites where old nests remain. Even remnants of deteriorated nests or leftover mud stains can draw them back year after year. If a nest appeared on your house last season and you left traces behind, that’s likely why they returned.
You Can’t Remove an Active Nest
Swallow nests are protected under the Migratory Bird Treaty Act. Under this federal law, it is illegal to destroy a nest that contains eggs or chicks, or if young birds are still dependent on the nest for survival. Violations are fully prosecutable, and the law applies to every homeowner, not just businesses or contractors.
The key distinction is between active and inactive nests. An inactive nest, one with no eggs, no chicks, and no birds using it for breeding, can be removed without a permit. You don’t need permission to knock down an empty nest. But if there’s any chance eggs or young birds are inside, the nest must stay. The U.S. Fish and Wildlife Service only issues removal permits for active nests under very limited circumstances, typically when a nest creates a genuine health or safety hazard.
The Nesting Timeline
Swallow breeding season runs from March through September. Once a pair settles on your house, eggs incubate for 13 to 17 days, and chicks take another 18 to 24 days to fledge. Even after fledging, young birds return to the nest for several more weeks before leaving for good. Many swallow pairs produce two clutches per year, each with 3 to 5 eggs, so a single nest site can be occupied for the bulk of the warm season.
This means your realistic window for legal removal is October through early March, before the birds return. If you discover a nest in April and it already has activity, you’re generally waiting until fall.
Health Concerns Worth Knowing
Swallow nests frequently harbor parasites, including swallow bugs, a close relative of bed bugs. Swallow bugs will bite humans, though people aren’t their preferred host. Mites and other insects also colonize nests over time, and these pests can migrate into your home once the birds leave and the nest goes dormant.
Droppings are the other concern. Accumulated droppings below a nest can stain siding, concrete, and outdoor furniture. In larger colonies, they create a genuine sanitation issue. When cleaning up after nest removal, wear gloves and a dust mask, wet the droppings before scraping to avoid inhaling dried particles, and bag everything for disposal.
How to Remove an Inactive Nest
Once you’ve confirmed a nest is empty and the breeding season is over, removal is straightforward. Old mud nests can be knocked down with a pole or washed off with a pressure washer. The critical step most people skip is removing all traces of mud from the surface. Swallows use old nest remnants as a foundation and a signal that the site is viable. If you leave a mud outline on your eave, expect them to rebuild in the same spot next spring.
Scrub the attachment point clean and, if possible, paint over it. This eliminates the visual and textural cues that attract returning birds.
Preventing Nests From Going Up
Prevention works best when installed before March, before swallows arrive scouting for nest sites. Several approaches are effective:
- Bird netting: Lightweight mesh draped under eaves or across the junction where roof meets wall physically blocks access to nesting surfaces. This is the most reliable method for large areas.
- Bird spikes: Commercial spike strips installed along ledges and beams prevent birds from landing and attaching mud.
- Vinyl strip curtains: For open entryways like barn doors or carport openings, overlapping vertical vinyl strips deter swallows from flying through.
- Interrupting construction: If you catch swallows in the early stages of building (before any eggs are laid), knocking down the fresh mud daily can discourage them enough that they relocate. Consistency matters here. Missing a day or two gives them enough progress to commit to the site.
Removing old nests each fall is the simplest form of prevention. A clean surface with no mud remnants is far less attractive than one with last year’s nest still clinging to it.
The Case for Leaving Them
Swallows are among the most effective natural pest controllers you can have near your home. A single barn swallow can consume up to 6,000 insects per day, targeting mosquitoes, flies, beetles, and other airborne pests. A nesting pair raising two broods catches an enormous volume of insects over a single summer.
If the nest is in a spot where droppings don’t land on walkways, patios, or entries, many homeowners find the tradeoff worthwhile. A small board mounted below the nest to catch droppings can solve the mess problem without removing the birds. You get free, tireless pest control from March through September, and the swallows leave on their own when fall arrives.
For nests in truly problematic locations, directly over a doorway, above outdoor dining areas, or near ventilation intakes, removal after the season ends and prevention before the next one begins is the practical approach. The goal is redirecting the birds rather than eliminating them. A nest box or sheltered ledge installed on a less-trafficked part of your property can give them an alternative site while keeping your main living areas clear.