Putty-nosed monkeys (Cercopithecus nictitans) live in family groups, usually led by a dominant male who keeps a wary eye out for their two main enemies â€” leopards and eagles. A circling eagle will cause a male to warn his troop by making a series of calls called 'hacks', whereas a lurking leopard will prompt him to shout out a string of 'pyow' sounds.
But now zoologists have realized that at least one combination of these sounds has its own distinct meaning: up to three pyows followed by up to four hacks seems to mean 'let's move on'. This call sequence is given both in response to the presence of predators or simply as a sign to head for new terrain.
And I wonder which sequence of hacks and pyows means, "Here come the humans, the time to overtake is NOW!!!"
(Props to new coworker, John.)