How to Keep Birds From Building Nests (and What the Law Says)
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How do you keep birds from building nests on your porch or house? Block the spot before the birds start: wash off old nests and mud in late fall or winter, close the corner, ledge or gap with rigid mesh or a steep slope, and check the spot every week once spring arrives. Do it before the first egg. The U.S. Fish and Wildlife Service (FWS) treats a nest as “in-use” once it holds a viable egg or nestling, and an in-use nest of a protected bird can’t be destroyed without federal authorization. Ultrasonic gadgets, scent sprays and plastic owls are the weak links in most advice, including the old version of this article. This is general information, not legal advice; check your state and FWS before removing any nest.
| Where | What works (per the sources) | When | Limits and law |
|---|---|---|---|
| Porch corners, beams, ledges (mud nests) | Wash away old nests and mud traces; block the corner with rigid mesh; on a flat ledge, add a board sloped at least 45° (Penn State) | Late fall to winter, before spring migrants return (FWS) | If mud is going up, wash it off daily until the birds give up (Texas A&M, FWS). Stop the moment eggs appear |
| Porch lights, soffit fixtures | Screen off the fixture (Illinois Extension); clear twigs the day they appear | Before spring; weekly checks | If a nest with eggs is already on it, leave it and use another light (my editorial advice) |
| Door wreath | Take it down for the season or hang a flat, nest-free decoration instead (my editorial advice; no source covers wreaths) | Before nest building starts | A wreath that already holds eggs is an in-use nest: use another door until the young leave |
| Eaves, siding gaps, roof-to-wall joints | Seal gaps; close openings larger than 0.5 inch with wood, metal or wire mesh (Penn State); netting where roof meets wall (Texas A&M) | Fall and winter | Cavity nests are hard to spot (FWS). Confirm nothing is inside before you seal |
| Gutters, vents, chimneys, dryer vents | Covers and caps (Illinois Extension, Project Wildbird). Keep your dryer vent clear and capped | Before spring; recheck after storms | Same rule: empty first, then cap |
| Under decks, awnings, rafters | Netting under the rafters (Penn State) | Before birds return | Keep it taut and inspect it; loose netting can trap birds (my editorial advice) |
The four states of a nest, and what you may do
The FWS memo on nests (MBPM-2-02, January 15, 2025) defines the terms. Most native birds are covered by the Migratory Bird Treaty Act (MBTA), including their nests and eggs. A nest is in-use from the first egg until the nestlings fledge and no longer depend on it. It is inactive if it has no viable eggs or nestlings, including a nest still under construction.
| Stage | What FWS says | What to do |
|---|---|---|
| 1. Nothing there yet | Nothing to protect | Block it now (table above) |
| 2. Being built, no egg | Counts as inactive; destroying an inactive nest needs no permit, provided you don’t keep the nest or its contents | Remove the material the day you see it. Texas A&M words it more strictly: once a bird spends time in even an incomplete nest, wait until it is empty. If you are unsure, wait |
| 3. Egg or young (or you can’t tell) | In-use; destroying it requires MBTA authorization. The FWS leaflet says permits are usually limited to health or safety concerns or birds in immediate danger | Leave it alone. Don’t haze the birds off it (Audubon Great Lakes) |
| 4. Empty after the young left | Inactive again | Remove, clean, then block the spot the same day |
The checking is on you. FWS says the person removing a nest is responsible for making sure it really is inactive, and it flags colonial, burrowing and secretive nesters as the hardest to read. Three more limits: relocating a nest, even an empty one, needs authorization; keeping a nest or its contents is not allowed (so no souvenir nests); and eagle nests and nests of ESA-listed species stay protected even when empty. States, tribes and cities can add rules on top.
One group of exceptions: Illinois Extension lists house sparrows, European tree sparrows, European starlings and feral rock pigeons as not protected. Audubon still advises leaving even those nests alone unless you are certain, because a sparrow nest is easy to confuse with a native bird’s.
When to do it
There is no single date when birds “stop” building. Swallows nest from March through September and often raise two clutches (FWS); an older FWS note for the Midwest gives April through July as the heavy season. Illinois Extension suggests inspecting your house from early October through February and removing old nests before birds return. Swallows rebuild on old nests and even on traces of old mud (FWS), which is why the winter wash-down matters.
What works, what half-works, what doesn’t
- Works: exclusion. Penn State calls keeping birds out of a space the best way to reduce problems, costly at first but often cheapest in the long run. FWS lists coroplast, PTFE, plexiglass, plastic sheeting and silicone-based paint as barriers that can be a permanent fix. Use taut, rigid mesh and look at it weekly in nesting season.
- Works: persistence early. Wash away mud or knock down twigs every day while the nest is only started. FWS says birds may give up on a site after repeated failures. This is the only “active” tactic the legal sources endorse, and only while the nest is empty.
- Works: give them somewhere else. Audubon suggests nest boxes and shelves to draw birds to safer spots; FWS notes swallows will use boxes. Put it away from doors, such as a nesting shelf on a shed wall.
- Half-works: slopes and spikes. A steep slope removes the flat spot. Spikes can stop perching on ledges, but Penn State says small birds like house sparrows fit between the points and nest anyway. I would skip sticky gels and anything electric on a home; that is my editorial view.
- Half-works: scare devices. A review of the research (Gilsdorf et al., 2002) found effects variable, with some protection and better results from combinations. UNH Extension, writing for fruit growers, says birds get used to them, so change the method or location often, pair sight with sound, and put them out only when needed. Plastic owls work “reasonably well for a short time” and need moving once or twice a day. Reflective tape and chimes belong in this class. I found no extension test of foil specifically.
- Doesn’t work: ultrasonic repellers. A review of the efficacy studies (Erickson, Marsh and Salmon, UC Davis, 1992) found most birds don’t hear above 20 kHz and the devices unproven; Gilsdorf et al. call them ineffective.
- Doesn’t work: sprays and scents. FWS says repellents are not effective for swallows; Illinois Extension calls repellents generally ineffective.
- Don’t: use cats as guards. Audubon says keep cats indoors during nesting. An older version of this article suggested the opposite.
- Not proven: moving the feeder. Common advice, but none of the sources I read tested it. If a feeder sits next to your door, moving it costs nothing.
If the nest already has eggs in a bad spot
Expect to wait. Audubon puts fledging at about a month after laying; for swallows FWS gives 13 to 17 days of incubation and 18 to 24 days to fledge, and the young may return to the nest for several weeks. Put a sign near the nest, keep cats inside, use another door and limit visits. Watch for about a week of no activity before treating the nest as finished (Project Wildbird), since many songbirds nest more than once a season. FWS does not issue permits for nuisance complaints, so plan on waiting, then block the spot. For a threatened or endangered species or an eagle, call FWS or your state wildlife agency first.
Cleaning up: droppings and old nests
Texas A&M says droppings can be a health concern and mites can persist in empty nests for up to three years. For mud and empty nests it suggests a hose, or a pole and scraper, with gloves and a respirator mask. For dry droppings, the Illinois Department of Public Health (citing CDC) says to wet the area first with a low-velocity mist, because a high-pressure stream can send spores airborne. Wear disposable clothing and a well-fitted N95, such as a NIOSH-approved N95, seal the wet waste in heavy plastic bags, and keep people with weakened immune systems away. Large accumulations of droppings should go to a professional cleanup firm.
FAQ
What month do birds stop building nests? It varies by species and region. Swallows are active from March to September with up to two clutches, and the FWS Midwest note puts the main season at April through July. Watch for activity instead of a date.
Will aluminum foil keep birds away? Reflective objects fall in the “some protection, but birds get used to them” class (Gilsdorf et al.). I found no extension test of foil on a porch, so treat it as a short-term add-on, not a barrier.
Can I remove a house sparrow or starling nest? Illinois Extension and Audubon list house sparrows and starlings as unprotected by federal law, and Penn State says the same for pigeons. Identification is the risk: Audubon advises leaving a nest alone if you are not sure, and state rules can differ.
Is bird netting safe for birds? Only if it is installed correctly. Hang it before the birds arrive, keep it taut, and check it regularly. My concern is loose, floppy netting that can trap a bird; that is editorial advice, not a figure from the sources.
The nest is on my door wreath and I use that door daily. Can I move it? Not on your own while it is in-use. FWS says relocating a nest needs authorization. Use another entrance, put up a sign, and take the wreath down once the nest is empty.
Sources read for this guide: FWS Migratory Bird Permit Memorandum MBPM-2-02 (Jan. 15, 2025) · FWS — Bird Nests: What you need to know · FWS — Nuisance swallows · FWS — The Time is Now to Prevent Problem Bird Nests (2005) · Audubon — What should I do if I find a nest where it doesn’t belong? · Audubon Great Lakes — Nest in a bad location · Illinois Extension — Coexisting with nesting birds (2026) · Texas A&M School IPM — Tips to prevent barn swallow nests · Penn State Extension — Controlling birds around farm buildings · UNH Extension — Bird damage prevention (Eaton) · Erickson, Marsh and Salmon (1992) — High frequency sound devices lack efficacy in repelling birds · Gilsdorf et al. (2002) — Use of frightening devices in wildlife damage management · Illinois Department of Public Health — Histoplasmosis fact sheet · Travis Audubon — Stopping birds from nesting · Project Wildbird — How to stop birds from building nests on your house.
