Barn or cliff swallows usually arrive in April and leave in the fall. They are graceful fliers, colorful birds and beneficial to the environment. They can be found hunting for insects over lakes, ponds, fields, golf courses, and even over intersections.
Problems arise when swallows build their nests around schools and public buildings, although regular cleaning of bird poop with soap and water should eliminate concerns about histoplasmosis.
What to do
Exclusion is the most permanent approach – prevent them from building or returning to their nests. Frightening and repellents are not effective for barn or cliff swallows. Plastic net or poultry wire can provide a physical barrier between swallows and a nest site. Some grounds managers have prevented swallows from returning by washing nests down with a water hose. ONLY do this if there are no eggs or young in the nest. Other methods to prevent swallows include using slick surfaces discourage nesting or, if you have a new building, avoid overhanging eaves or other design structures that would encourage nesting.