Monkey Whispering: In Face of Potential Threat, Tamarins Lower Their Voices

Monkey Whispering: In Face of Potential Threat, Tamarins Lower Their Voices
Cotton-top tamarins, a type of monkey, use a technique similar to whispering in the face of potential threat, researchers found. In this file photo, three tamarins are at the Oakland Zoo in Oakland, Calif. (AP Photo/Justin Sullivan)
Zachary Stieber
9/25/2013
Updated:
7/18/2015

A study at the Central Park Zoo has found that a species of monkeys use whispering in the face of a potential threat, instead of mob behavior as was previously seen.

Using a video camera and microphone--and a zoo staff member that the monkeys were not fond of--researchers studied how tamarins behaved when presented with a potential threat.

Tamarins have multiple predators and have in the past utilized several different methods to protect themselves, including freezing, escape, and mobbing, according to two previous studies.

The mobbing display was observed as manifesting through whistles, chirps, squeaks, among other vocalizations, as well as barks, growls, and high-chirp trills.

The researchers--Rachel Morrison from the Department of Psychology at the City University of New York, and Diana Riess, of the Department of Psychology at Hunter College--chose a supervisor who was known to elicit a strong mobbing response from the tamarins, and exposed the monkeys to the supervisor.

The researchers expected that the tamarins would respond by mobbing the supervisor.

However, the tamarins responded to the potential threat by lowering their communication levels--similar to whispering--or “a marked reduction in the amplitude of their calls,” write Morrison and Riess in the journal Zoo Biology

“This report indicating that these tamarins were lowering the amplitude of their signals in the presence of a potential threat provides the first evidence for whisper-like behavior in a non-human primate,” they write. “The presence of this phenomenon may be an alternative anti-predator strategy to a full blown mobbing response.”

“Whisper-like behavior may be a more widespread phenomenon than previously thought, but due to its inherent subtlety it has eluded prior detection,” they add.