Gibbons have accents: study

The researchers, who published their study in the journal BMC Evolutionary Biology, said their findings could be used to identify the species of gibbon singing and where they are from.

"Each gibbon has its own variable song but, much like people, there is a regional similarity between gibbons within the same location," said Van Ngoc Thinh, who led the study at the German Primate Center in Goettingen.

According to the researchers, the crested gibbons (genus Nomascus), which live in the Asian rain forests of China, Laos, Cambodia and Vietnam, communicate with other gibbons by singing.

They also use singing to bond with mates and define territory. The songs are specifically adapted to travel over long distances through the dense vegetation of the rain forest by concentrating all of the energy into a single frequency, similar to the calls used by rain forest birds.

For their study, the researchers analysed the singing of more than 400 gibbons from 92 groups in 24 different locations. They then compared the song information with the species and location of the gibbons.

Genetic diversity between the species was also measured by looking at mutations in the gene coding for mitochondrial cytochrome b.

It was found that the four most related songs came from the gibbon species with the most closely related DNA and geographical location, from Cambodia, Laos and Vietnam.

And the gibbons from the southern most areas were found being more closely related to each other than to the more northerly Vietnamese gibbons and gibbons from China.

The gradation of song similarity between the northern and southern populations supported the idea that the genus began in the north and migrated toward the south, the researchers said.

Since it is difficult to obtain genetic samples from the animals and their coloration is variable within a species, being able to identify a gibbon by song enables better monitoring of their populations, they added.