Editing Cliff swallow (section)

=== Vocalisations ===
{{Birdsong|url=http://www.xeno-canto.org/species/Petrochelidon-pyrrhonota|species=American cliff swallow}}The social structure of these cliff swallow colonies has evolved a complex [[Bird vocalization|vocalisation]] system.<ref name=":2" /><ref name=":1" /><ref name=":7" /> Five vocalisations have been identified, which are used by both juveniles and adults for different reasons.<ref name=":2" /> These vocalisations are structurally similar across the age groups and can be described as begging, alarm, recognition, and squeak calls, all with some variations.<ref name=":2" /> Juvenile 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.<ref name=":2" /><ref name=":1" />

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.<ref name=":1" /> When this call is heard, large groups of their colony "neighbours" will arrive at the location.<ref name=":1" /> This "squeak" call is used greatly during bad weather conditions.<ref name=":2" /><ref name=":1" /> For this specific call, the cliff swallows are one of the few known [[vertebrate]]s to make a "competitively disadvantageous" cue to their peers for food availability.<ref name=":1" />

Alarm calls are heard at the colony while the birds are flying over and around the colony entrance way, and 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.<ref name=":1" />
[[File:American_Cliff_Swallows,_PE_Cty.jpg|right|thumb|Collecting mud at a puddle, [[Prince Edward Point]], [[Ontario]]]]