Dr. Jacob Dunn of Anglia Ruskin University, the co-author of a study on red-handed tamarins, published in the journal Behavioral Ecology and Sociobiology, discovered that when monkeys of the species are spotted in the territory of a rival gang, they speak like their rivals to avoid a bloody turf war. He said: “They’re are saying the same word but using another accent.”
The reason, as indicated, is that they want to avoid violence. It is the first known example of one type of monkey imitating the calls of another and it improves communications with the species which in turn helps to remove the possibility of violence.
The researchers observed 15 groups of pied tamarins and red-handed tamarins in the Brazilian Amazon near the city of Manaus. In this area they frequently compete for food and other resources. The risk of conflict is high as a result but, as mentioned, when red-handed tamarins encroached into pied tamarin territory, they adopted the sounds of their rivals. Their calls change subtly. It is reported that their cries “had fewer overtones and undertones and shifted in frequency, becoming a little lower. The result was a noise far closer to those made by the pied tamarins.”
This behaviour is called “asymmetric call convergence” in primates which means one species choosing to adopt another species’ call patterns.
The lead author of the study, Tainara Sobroza of the Instituto Nacional de Pesquisas da Amazonia, said: “When groups of tamarins are moving quickly around mature forest it can sometimes be difficult to tell the species apart, but during our research we were surprised to discover they also sound the same in the areas of the forest they cohabit. We found that only the red-handed tamarins change their calls to those of the pied tamarins, and this only happened in places where they occur together. Why their calls converge in this way is not certain but it is possible to help with identification when defending territory.”
Note, I’m indebted to Rhys Blakely, the Science Correspondent of The Times newspaper.
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