Swallow
Barn and cliff swallows plaster mud nests under eaves, docks, bridges, and parking structures.
How to identify
Small, fast-flying birds, about 5 to 7 inches long. Barn swallows have deeply forked tails and dark blue backs; cliff swallows have square tails and buff rumps.
Why it is a problem for commercial facilities
Swallows build heavy mud nests on eaves, underpasses, and docks. Nests deface structures and host swallow bugs, a parasite similar to bed bugs.
Protected status
Federally protected under the Migratory Bird Treaty Act (MBTA). Birds, active nests, and eggs cannot be harmed or disturbed without a U.S. Fish and Wildlife Service permit. Deterrents and exclusion installed before nesting do not require a permit. Once a nest holds eggs or chicks, it cannot be touched, so inactive nests must be removed and barriers installed before spring arrival.
How BSI controls it
- Bird exclusion netting under eaves and overhangs
- Slope systems that prevent mud nests from adhering
- Removal of inactive nests and cleanup before the nesting season
Where we see it most
Transit, Municipal and government, Commercial and industrial.
Common questions
When should swallow control be installed?
Before birds return in spring. Installing barriers before nesting is legal and far more effective.
Can I knock down swallow nests?
Only inactive nests with no eggs or chicks. Active nests are protected under federal law.
Dealing with this species at your facility?
Send two photos and the project location. We will come back with a recommended system and scope.