The researchers observed two populations of vocalising orangutans in Borneo and Sumatra across a total of 3,800 hours. They found that primates within both groups used the same vocal phenomenon.

Of greatest conservation concern is the orangutan, which occurs naturally on only two islands in the world, Borneo and Sumatra, and is under increasingly severe pressure, primarily from habitat loss.

A boy is missing on Indonesia's Borneo island after he was attacked by a crocodile, ... That same month, a 63-year-old tin miner was killed by a crocodile near a river on Bangka island in Sumatra.

The researchers observed two populations of vocalising orangutans in Borneo and Sumatra across a total of 3,800 hours. They found that primates within both groups used the same vocal phenomenon.