These are mud swallows or barn swallows and they build and nest in the mud structures you see above. They come to this area in the spring to build and mate. When they arrive, they swarm the peaks of your home and little bit at time, they pack mud and grass together to construct their nests. They are not dangerous but a pest, because of the mess.
One of our current clients has a beautiful home in Gallatin River Ranch, and every Spring the mud swallows nest in the peaks of their home. They are tired of cleaning up after the birds, so they asked us to research tactics to rid their house of the birds.
Last Fall we blasted all the vacant mud homes away with a pressure washer once the birds migrated south. This Spring we rented a paint sprayer and sprayed their house with canola oil. When the birds came and tried to build the mud would not stick to the house. The swallows didn't stay long before they became discouraged and left.
This client could not be happier and we now have an excellent new marketing tactic.