Scientists have deciphered the “giggle” sound of spotted hyenas, which they claim reveals information about age, dominance and identity of the animals.
An international team has carried out an acoustic analysis of spotted hyenas’ laughter and found that variations in the giggles’ pitch and timbre help the animals to establish social hierarchies, the ‘BMC Ecology’ journal reported.
“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 organise their food-gathering activities,” lead scientist Frric Theunissen of California University said.
For their study, the scientists recorded the calls of 26 hyenas in captivity. They found that while the pitch of the giggle reveals a hyena’s age, variations in the frequency of notes can encode information about dominant status.
These vocalisations are mainly produced during food contests by animals that are prevented from securing access to a kill, and have been considered a gesture of submission, the scientists say.
The team also suggests that the giggle may be a sign of frustration and that it may be intended to summon help.
“Lions often eat prey previously killed by hyenas. 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, status) and decide to join the giggler or conversely to ignore it,” said Mr. Theunissen.
The scientists now plan to further test these hypotheses with playback experiments in the field.