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.