Singing lemurs may use a soprano-like trick to project songs

High in the rainforests of northeastern Madagascar, a unique species of primates called indris are using a vocal technique similar to that of opera singers to project their haunting songs. According to a new study published in the journal PLOS Computational Biology, these lemurs open their mouths wider when producing higher-pitched notes, a phenomenon that changes the shape of their vocal tract — akin to how a longer or shorter tube on a wind instrument alters its tone.

This adjustment, the researchers believe, boosts the power and distance of their voices. The study, led by Filippo Carugati from the University of Turin, tracked 83 video recordings of 19 wild indris in Madagascar's Maromizaha forest and Mitsinjo reserve. The facial expressions of the lemurs were analyzed frame by frame, paired with synchronized audio, to determine whether mouth opening predicted pitch.

The researchers found a very strong statistical correlation between the two. The indris' songs, described as a haunting blend of wailing and singing, serve multiple social functions, primarily acting as a territorial call. These songs tend to be longer when the group visually encounters another group nearby, suggesting that their songs help maintain territories and avoid confrontations.

The researchers hope that this discovery sheds light not only on the indris' extraordinary vocal ability but also on the critically endangered status of these unique primates.