Swallow Nests on Your House: The Rules, the Timing and the Mess on Your Windows
Every spring, cliff swallows return to coastal Orange County, San Clemente included, the same birds made famous at nearby Mission San Juan Capistrano. They build mud nests under eaves, often right above windows, and leave mud and droppings on the glass below. Here’s what California allows, when, and how to deal with the mess.
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Know Before You Touch a Nest
Can you remove swallow nests from your house? Not during nesting season. Cliff swallows are protected under the Migratory Bird Treaty Act, and in California completed nests can’t be touched from February 15 to September 1 without a permit from the U.S. Fish and Wildlife Service. Outside those dates, empty nests can be removed, and netting or smooth surfaces help keep swallows from rebuilding.
The Swallow Calendar in Southern California
| When | What happens | What you can do |
|---|---|---|
| Late February to early March | The first cliff swallows arrive in Southern California | Have netting up before they start building |
| Spring | Nest building. One nest takes 1,000 to 1,400 mud pellets | Expect mud splatter on windows and walls below |
| February 15 to September 1 | California nesting season. Completed nests are protected | Clean windows and droppings, but leave active nests alone |
| After September 1 | Swallows leave; nests are empty | Remove old nests, clean up, and add exclusion for next year |
These dates follow California’s nesting season rules.
The Mess on Your Windows
Mud splatter. Swallows carry mud up to the eave one pellet at a time, and some of it drips or falls onto the glass and sills below.
Droppings. A busy colony leaves streaks down windows, on sills and on screens right under the nests.
Nest bugs. Swallow nests often carry mites and swallow bugs, which are related to bed bugs and will bite people. Don’t poke at nests.
Timing matters. Cleaning glass below active nests is fine, but a full cleanup and old nest removal waits until after September 1.
Cleaning Windows Around Swallow Nests
Nest removal and netting are separate jobs, usually done by bird control companies after the season. Keeping the windows clean in between is where a recurring window cleaning schedule helps.
Droppings on Your Windows?
Tell us which side of the house the nests are on and how many windows are affected. You’ll get a free quote.
Prevention That Works
Netting is the most effective option: 1/2 to 3/4 inch mesh running from the outer edge of the eave down to the wall, installed before swallows arrive. Smooth surfaces, like sheet metal or a fresh slick coat of paint where they build, also discourage nesting. Fake owls, snakes and noise makers have shown little success.
Other Birds, Same Windows
Gulls and pigeons leave droppings on ocean-facing glass year-round. Soak it before wiping, never scrape it dry, and clean it off soon. See ocean-view window cleaning.
Swallow Nest FAQs
Clean Windows, Swallow Season or Not
Tell us where the nests are and how many windows need it. You’ll get a free quote.
