Busy flocks of Cliff Swallows often swarm around bridges and overpasses in summer, offering passers-by a chance to admire avian architecture and family life at once. Clusters of their intricate mud nests cling to vertical walls, and when a Cliff Swallow is home you can see its bright forehead glowing from the dim entrance. These common, sociable swallows are nearly always found in large groups, whether they’re chasing insects high above the ground, preening on perches, or dipping into a river for a bath.