Researchers Rachel Morrison and Diana Reiss of The City University in New York were doing a research project on the monkeys by recording their loud calls and “mobbing behavior” in response to seeing people they fear. But, when a supervisor whom the monkey disliked entered their enclosure, the researchers noticed that the monkeys went quiet.
It turns out that the tamarins weren’t exactly silent. When Morrison and Reiss examined their recordings, they realized that the monkeys were still chirping, but in a volume too soft for humans to hear. In effect, the tamarins were whispering to each other, potentially about what to do about the intruder.
via Neatorama
Image: Ltshears/Wikipedia
