National Geographic reports on the results of a study that found that Japanese macaques (Macaca fuscata) have regional accents. The researchers chose two groups of monkeys in Japan that were descended from the same original population but now reside hundreds of miles apart. They found that one group had an average 'tone' (I assume they mean 'fundamental frequency') that was 110 hertz higher than the other.
The researchers offer an intriguing acoustic explanation for the difference. One of the groups of monkeys has been living for decades in a forest while the other has been living in a rocky area with little vegetation - two very different acoustic propagation environments. High frequencies would tend to travel better than low frequencies in the forest and that correctly corresponds to the monkeys living in the forest using the higher frequency.
The researchers controlled for several factors (sex, time, type of vocalization, and activity) and analyzed a large sample of data to come up with their results. The full paper will be published in this month's Ethology (German scientific journal).