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Often seen flying in swarms over open to semi-open areas especially near water, cliff swallows forage by hovering in flight and then diving into a mass of airborne insects. They are also known to perch on vertical surfaces, such as the sides of cliffs and bridge overhangs, constructing gourd-shaped mud nests with small entrance holes. Cliff swallows are colony nesters, and they build their distinctive nests in a wide variety of habitats throughout the West, expanding into eastern North America as well. These aerial insectivores use th