Contact call

Contact calls are seemingly haphazard sounds made by many social animals (such as a chicken's cluck). Contact calls are unlike other calls (such as alarm calls) in that they are not usually widely used, conspicuous calls, but rather short exclamations that differ between individuals. Often, the message that the call is meant to convey is specific to the individual or group's activity, such as informing other members of the group about one's location while foraging for food. Some social animal species communicate the signal of potential danger by stopping contact calls, without the use of alarm calls. Charles Darwin wrote about this in relation to wild horse and cattle. Contact calls are seemingly haphazard sounds made by many social animals (such as a chicken's cluck). Contact calls are unlike other calls (such as alarm calls) in that they are not usually widely used, conspicuous calls, but rather short exclamations that differ between individuals. Often, the message that the call is meant to convey is specific to the individual or group's activity, such as informing other members of the group about one's location while foraging for food. Some social animal species communicate the signal of potential danger by stopping contact calls, without the use of alarm calls. Charles Darwin wrote about this in relation to wild horse and cattle. Joseph Jordania suggested that human humming could have played a function of contact calls in early human ancestors. According to his suggestion, humans find it distressing to be in full silence (which is a sign of danger for them), and this is why humans who are alone sometimes hum, whistle, talk to themselves, or listen to TV or radio during other activities. Birds use contact calls in flight to establish location and to keep aware of each other's presence while flying and feeding. For some species, this call consists of a short, high-pitched sound, recognized and duplicated exactly by mates. Some fowl, such as geese,'honk' while in migration to communicate location and proximity to others in their flock. In parapatric and sympatric species of birds, where territories of one species may border or overlap with that of another species, the contact calls of each species may divergently evolve to help differentiate one species from that of the other within close proximity. Where one species may have little to no variation among the contact calls of distinct allopatric populations, populations with overlapping territories may change their contact call to sound different from the bordering population's. The same variation pattern is seen in certain species of birds, such as the White-eyed Birds (Zosterops spp.) with increasing elevation and longitude/latitude. Some species of birds have alarm calls to specifically warn other individuals of predators. The Black-capped Chickadee warns its kind of the level of threat an approaching predator is by the number of 'de's heard. Its call, chick-a-dee-dee-dee, might indicate more danger than chick-a-dee-dee. Some calls reveal more details about an approaching predator, indicated by the pitch or speed. When there is a threatening enemy in the air, such as a hawk or eagle, the Florida Scrub-Jay warns other jays to seek cover by using a thin, shrill-like call. In contrast, an approaching predatory feline provokes a low-pitched 'scolding' sound, and calls on fellow jays for help in scaring the intruder away. Parrots kept as pets demonstrate contact calls with their human owners. Parrots make their call to establish that the human is within earshot, and continue to make the call (sometimes growing louder into a scream) until acknowledged. The screaming develops in pet parrots, as well as wild flock, when the animal feels like its needs are not being met because the contact call is not being understood.