Because swallows build durable nests of mud and grass, their presence creates lasting damage to the eaves and barns where they so often choose to roost. As a migratory bird, international laws prohibit killing, injuring or relocating these songbirds, so you must deter the swallows from selecting your yard for their nests. Companies market chemical repellents and predator decoys to frighten swallows, but these products seldom work as advertised. Instead, you must focus on physical barriers to protect your eaves from their mud nests.
Purchase metal spike strips from the home and garden store.
Place the strip on any flat surface under your eaves.
Nail the spike strip into place.
Place the second strip against the end of the first strip, so that the swallows cannot land in between them.
Nail into place and continue, until the spikes line the surface.
Purchase bird netting appropriate for birds 5 to 8 inches long.
Place the long end of the netting to the underside of the eaves, near your gutters, if you have them.
Nail or tack the net into place.
Place the opposite end of the net under any flat surfaces where a swallow may land.
Nail or tack the net into place, leaving it slightly loose, so it won't pull out as easily.
If your eaves are large, you may need to place more than one row of spikes to deter sparrows. Instead of netting, you can also use solid barriers to cut the angle between the siding and eaves, physically blocking the landing spots. These are more difficult to install but may prove more effective against determined swallows. If the sparrows still nest on your house, you can call a licensed professional to remove the nests.