Despite their history, many homeowners see the swallows as a nuisance because of the large amount of droppings they leave. But once the birds decide to share a home and start building nests, it's illegal to get rid of them. Cliff swallows, as well as all other migrating birds, are protected by the federal Migratory Bird Treaty Act. Although people can legally prevent the birds from building nests, once eggs are laid they are protected under federal law. It takes a swallow a few weeks to build a nest.
Eggs hatch several weeks later and the babies are ready to leave the nest about a month later.
Although Frankos agrees the bird droppings are a hassle, he's philosophical about it. We must be nice people because they could have gone anywhere and they chose to visit us.