Barn swallows feed on the wing, snagging insects from just above the ground or water to heights of a hundred feet or more. They fly with fluid wing beats in bursts of straight flight, rarely gliding, and can execute quick, tight turns and dives. When aquatic insects hatch, barn swallows may join other swallow species in mixed foraging flocks. Their sturdy adobe mud nests are popular with many species of nesting birds, who move into the empty nests when no barn swallow is around to protest. Barn swallows migrate every year. As winter ends and spring approaches, most barn swallows start their migration journey north, leaving their wintering grounds in South and Central America in February, and arriving at their summer breeding grounds by late April to early May.