Singing in the rain forest: Gibbons have accents

One of 2,500 yellow-cheeked crested gibbons counted in a 2008 Wildlife Conservation Society survey in Cambodia.

Groups of the apes have their own ways of singing, which vary by location

2/7/2011
By Jennifer Welsh
LiveScience

Gibbons have regional accents, a new study suggests. While not a sexy Southern drawl, these accents can help scientists 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," lead researcher Van Ngoc Thinh, from the Primate Genetics Laboratory at the German Primate Center, said in a statement.

The crested gibbons in the genus Nomascus, which live in the Asian rain forests of China, Laos, Cambodia and Vietnam, use their songs to communicate with other gibbons. 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.

After analyzing the singing of more than 400 gibbons from 92 groups in 24 locations (six different species all together), the researchers compared the song information with the species and location of the gibbons. They also compared it to the genetic variation between these groups. The researchers found that each group of gibbons had its own slightly different way of singing, which varied by location. The songs could be used to pinpoint a gibbon to a species and a location.

They also noticed that the subtly different songs varied with genetic diversity, so those species that are the most closely related had the most similar accents, while those that weren't closely related had songs that were the least similar. The group of four southern species (N. leucogenys, N. siki, N. annamensis and N. gabriellae) was the most closely related, and needed a more detailed analysis to differentiate between them.

The gradation of song similarity between the northern and southern populations supports the idea that the genus began in the north and migrated toward the south, the researchers said. Being able to identify a gibbon by song enables better monitoring of their populations, since it is often difficult to obtain genetic samples from the animals and their coloration is variable within a species.

The paper was published Jan. 6 in the journal BMC Evolutionary Biology.