Barn Swallow

Both male and female build the nest cup using mud. They collect mud in their bills and often mix it with grass stems to make pellets. They first construct a small shelf to sit on, then build up the nest’s sides. If built against a wall or other vertical surface the result is a semicircular, half-cup shape. Nests built on top of a beam or other horizontal surface form a complete cup about 3 inches across at the rim and 2 inches deep. The birds line the cup first with grass, then feathers, and in colonies may steal nest-lining materials from neighboring nests. When reusing nests, Barn Swallows clean out old feathers and add new mud to the nest’s rim.