Evrim Yazgin
Cosmos science journalist
Reproductive success in male rock hyraxes is linked to their ability to maintain rhythm during courtship songs according to a new behavioural study of the diminutive mammals.
The study is published in the British Ecological Society’s Journal of Animal Ecology.
It’s a well-established fact that musical talent can be seductive. But whipping out a guitar or singing a ballad only really works if you’re any good. It seems the same rules apply in the animal kingdom.
Among rock hyrax males, it seems singing frequency and rhythm are seen by potential mates as indicators of suitability. Perhaps musical skill is a signal of health and good genetics.
“We have been studying hyraxes for the past 20 years and have previously found several patterns in their songs that are common features of human language and music,” says Dr Vlad Demartsev, who collected data on the rock hyraxes while at Israel’s Tel Aviv University. Demartsev is now a postdoctoral researcher at the University of Konstanz and the Max Planck Institute of Animal Behaviour, both in Germany.
“Their songs have regional dialects so individuals living in proximity sing more similarly to each other. They tend to sing in crescendo (getting louder as the song progresses) and reach peak complexity towards the end of their songs, maybe to keep the audience engaged and listening to the signals,” Demartsev adds.
Though they look like rodents, the small, furry rock hyrax’s closest living relatives are actually elephants and manatees.
Their upper incisors grow nonstop into small tusks. Rock hyraxes can be found throughout much of Africa and parts of the Middle East in rocky, scrub-covered areas.
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Demartsev notes that it is common for rhythm to be important in animal communication.
“One assumption is that rhythm has evolved so that animals that call in groups can better synchronize their songs – like musicians in a band or singers in a choir.”
However, rock hyraxes are solo artists, usually singing alone.
The team’s findings show that male rock hyraxes keep a stable tempo with sounds occurring at regular intervals, known as isochronous rhythm.
“Male hyraxes that sing more frequently tend to have more surviving offspring,” says co-founder of the study Dr Lee Koren, a researcher at the Bar-Ilan University in Israel. “Song rhythms and stability are related to reproductive success and thus potentially hold information about individual quality.”
Certain illnesses and physiological problems may have a negative impact on the hyrax’s ability to sing in time, like a singer with a cold. The researchers believe that females might be able to pick up on imprecise rhythms as indicators of subpar health and mating suitability.
While rock hyraxes seem to advertise their health through singing their rock songs, other species use rhythm to help coordinate signals from individuals within a group. It is not yet known if different rhythmic patterns are used in performing these two distinct functions.
“It would be fascinating to compare animal species who sing individually and species that sing in groups,” adds Demartsev.