EAST ANGLIA, United Kingdom — Monkeys mimic the “accent” of another species when they enter their territory to help avoid conflict, reveals new research. The groundbreaking study is the first to show that one species chooses to adopt the call patterns of another.
Researchers investigated the behavior of 15 groups of pied tamarins and red-handed tamarins in the Brazilian Amazon. Pied tamarins are classed as “critically endangered” and have one of the smallest ranges of any primate in the world, much of it around the city of Manaus, while red-handed tamarins are found throughout the north-eastern Amazon region.
The researchers found that when groups of red-handed tamarins entered territory shared with pied tamarins, the red-handed tamarins adopted the long calls used by the pied tamarins. They say that red-handed tamarins have greater vocal flexibility and use calls more often than pied tamarins.
The researchers believe that the red-handed tamarins might alter their calls to avoid territorial disputes over resources.
“When groups of tamarins are moving quickly around mature Amazonian 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,” says study lead author Tainara Sobroza, a PhD student at the National Institute of Amazonian Research in Brazil, in a statement. “We found that only the red-handed tamarins change their calls to those of the pied tamarins, and this only happens in places where they occur together. Why their calls converge in this way is not certain, but it is possibly to help with identification when defending territory or competing over resources.”
“We have long known that when closely related species overlap in their geographic ranges, we are likely to see interesting evolutionary patterns,” adds co-author Dr. Jacob Dunn, an associate professor in Evolutionary Biology at Anglia Ruskin University, “One famous example is the Galapagos finches, studied by Darwin, whose beaks evolved to specialize on different foods on the islands to avoid competition. In some cases, rather than diverging to become more different from one another, some closely related species converge to show similar traits. Our study is the first to show asymmetric call convergence in primates, with one species’ call becoming the ‘lingua franca’ in shared territories.”
Dunn says the unique behavior is likely a way for the tamarins to share the forest and available resources without facing conflict.
The findings are published in the journal Behavioral Ecology and Sociobiology.
SWNS writer Stephen Beech contributed to this report.