When birds move into the house they create noise, leave droppings, and may carry diseases into your home. Keeping birds from nesting in or on your home is a matter of prevention. Some species are protected by law and it is a crime to destroy active nests. You want to prepare your home during the season when the birds are not there.
Nests in Holes
A broken cover on a dryer vent or a broken window in the attic looks like a hollow tree to birds. In the off season, make sure that all openings that look like home sweet home to our feathered friends are covered up. Any flat areas, or outdoor potted plants, can become nest sites. There are commercial products that make these areas less desirable for birds, usually wiring that makes it hard to build a nest.
Nests on Walls
Some types of birds, like swallows, build mud nests that stick to any textured surface. You can knock them down with a hose or a broom handle, but only when they have just been started, not after they have eggs. You can place netting, aluminum foil, or plastic sheeting where they will discourage the birds.
If you do not want birds around, do not plant anything that provides food for them.