Many social animals produce seemingly haphazard and indistinctive sounds (like chicken cluck) when they are going about their everyday business (foraging, feeding).
Its call has been compared to the clucks of a chicken, with clucks of chuk-chuk-chuk or choop-choop-choop being made at a constant rate of eight notes every five seconds.
To signal friendly or submissive behavior, alpacas cluck, or click a sound possibly generated by suction on the soft palate, or possibly in the nasal cavity.