26 captive spotted hyenas were part of the first ever effort to decipher hyenas' calls. The study was conducted at UC Berkeley, where the beasts' vocalizations were recorded and analyzed in a variety of social situations.
The pitch of the call indicated a hyena's age, while changes in frequency correlated to each individual's hierarchical status within the group. In all, hyena's have 10 types vocalizations.
Whoops with longer intervals signal separation between individuals (that might explain my own nearly nine hours of daily whooping, what with me being separated from my family and contained in an accounting office).
Grunts and soft growls signal close contact with members of the same clan (that, too, explains the sounds my youngest boy emits each day when he comes toddling up to me as I walk in the door from work).
Photo via BBC
Oddly, there were no vocalizations indicating proximity to pizza, a sound researchers have tabulated in my own behavior. You know: eager yelps, devouring growls, and satisfied groans.
Thanks for the article, Ida.