A new study published in open access journal BMC Ecology has revealed that the “giggle” sound made by spotted hyenas encodes information about age, dominance, and identity.
After recording the calls of 26 hyenas in captivity, researchers from the University of California at Berkeley and Université Jean Monnet Saint-Etienne in France found that variations in the giggles’ pitch and timbre may assist the animals in establishing social hierarchies.
“The hyena’s laugh gives receivers cues to assess the social rank of the emitting individual. This may allow hyenas to establish feeding rights and organize their food-gathering activities,” said researcher Frédéric Theunissen of Berkeley in a press release.
At their field station at Berkeley, the researchers discovered that while the pitch of the giggle reveals a hyena’s age, variations in the frequency of notes can signal the animal’s dominant and subordinate status.
These vocalizations are mostly produced during food contests by animals that are prevented from obtaining the food they preyed on.
Along with his colleagues, Theunissen also suggested that the giggle may be a sign of frustration and seeking for help.
“Lions often eat prey previously killed by hyenas,” said Theunissen. “A solitary hyena has no chance when confronted by a lion, whereas a hyena group often can ‘mob’ one or two lions and get their food back.”
“Giggles could therefore allow the recruitment of allies. Cooperation and competition are everyday components of a hyena’s life. When hearing a giggling individual, clan-mate hyenas could receive information about who is getting frustrated (in terms of individual identity, age, status) and decide to join the giggler, or conversely to ignore it or move away.”
The researchers plan to further test these hypotheses with playback experiments in the field.
The research paper is available as a PDF HERE.