These birds are day-hunters (diurnal), returning to their nesting sites at dusk, and are not very active during cold or rainy weather because of the low number of prey available. Foraging behaviors related closely to their reproduction cycle; when the birds first arrive at the nesting site they will forage as far as 10 miles from the colony, in the hopes of increasing body fat reserves to prepare for cold-windy days and their energy extensive egg-laying stage. When the swallows return to the nesting site at dusk, they often fly in a tightly coordinated flock above head, in such close synchronization, that they may appear as one large specimen. These large group formations are called creches. The American cliff swallow's social behavior does not end with these “synchronized flying” displays; they use special vocalizations to advise other colony members of a good prey location where ample food is available. It has been thought that colony sites located close to marshes would have larger quantities of insects to support big populations, however there are equally large nesting colonies located at a great distance from marshes. The social structure of these cliff swallow colonies have evolved a complex vocalisation system. Five vocalisations have been identified, which are used in both juveniles and adults for different reasons. These vocalisations are structurally similar across the age groups and can be described as: begging, alarm, recognition and squeak calls all with some variations. Juvenile American cliff swallows are said to have established a unique call by the approximate age of 15 days, which allows the parents to identify their chick from others in the colony. The “squeak” call is of great interest to researchers because this is the special vocalisation made at a distance from the colony when a bird encounters a good foraging area. When this call is heard, large groups of their colony "neighbours" will arrive at the location. This "squeak" call is used greatly during bad weather conditions. For this specific call, the cliff swallows are one of the few known vertebrates to make a “competitively disadvantageous” cue to their peers for food availability. Alarm calls are heard at the colony while the birds are flying over-and-around the colony entrance way, they serve as a signal of danger close to the nests. When this call is heard by the other colony members, a mass fleeing of birds out and away from their nests is observed. The breeding season of American cliff swallows starts with the return of the birds from their wintering grounds, they usually arrive in large groups and start immediately to choose their nesting sites.