鈥淧YOW pyow hack hack hack鈥�. Or, to translate from monkey-speak: 鈥淐鈥檓on. We鈥檙e outta here.鈥� That鈥檚 how male putty-nosed monkeys tell their group it鈥檚 time to move on.
Kate Arnold of the University of St Andrews, UK, noticed the call during experiments in Nigeria to test how wild groups of these tree-dwelling monkeys (Cerceopithecus nictitans) respond to recordings of noises of predatory leopards and eagles. The dominant males in groups of 15 to 25 females will make 鈥減yow鈥� sounds when leopards are prowling nearby, and 鈥渉ack鈥� sounds when eagles are alarmingly close.
The males would also utter a mixture of the terms no matter which of the two animal recordings they heard. Arnold began to notice a distinct 鈥淧yow pyow hack hack hack鈥� motif thrown in. Listen to the calls here (.wav format, 3MB).
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The phrase was uttered more often after Arnold and her colleague Klaus Zumberb眉hler replayed the leopard recording. Arnold says the groups are more likely to move away to escape a prowling leopard, but stay still and out of sight if an eagle is overhead. Crucially, males also issued the phrase when no predators threatened, to prompt foraging in the mornings and find somewhere to sleep in the late evenings (Nature, vol 441, p 303).
鈥淲e heard it whenever the male wanted the group to move,鈥� says Arnold.
