Female Putty-Nosed Monkeys’ Warning Calls Summons Males To Fight Off Predators

A little help from your friends can come when you see yourself facing the enemy, and new research published in the Royal Society of Open Science Journal has found that some monkeys also call for back up.

Targeting a population of putty-nosed monkeys (research researchers) discovered that females would only use specific calls to target males, who would jump like “hired guns” to get predators on their backs. The scientific team, in collaboration with the Congo Program of the Wildlife Conservation Society (WCS) and the Nouabalé-Ndoki Foundation, looked at 19 wild patty-nose monkeys for research. Each found in Ndoki Bay, a designated area for research that sits in the forests of Nouabalé-Ndoki National Park in the northern Republic of Congo.

Groups using specific alert calls are a common occurrence among primates, who have learned to respond to alert calls and respond appropriately, sometimes even picking up calls from other species (captive orangutans have even established a new way of communication not seen in the wild).

Males carry some of the highest alarms in forest genotypes (monkeys of the genus Cercopithecus, including putty-nosed monkeys) but they are necessarily more specific than females, as the single word can be use in many activities. The researchers in this study wanted to test experimentally that if sex differences came up in alarm call techniques, they listed the help of a “leopard”, which was convincing enough to make the moving nose monkeys think they were in attack. They release the leopard into male and female groups separately, to see how other monkeys, of the opposite sex, have responded to their call.

Interestingly, when the female monkeys spotted the leopard and raised alarm, the males would run away, but the same effect did not occur when the males raised the alarm. Before recruiting men know what is going on, they will build a racket on their approach that researchers suggest could play a role in establishing the value of men within this group. 

The male call then switches the leopard to a specific anti-predator call and only the female will turn off the voice. Various strategies may tied to the fact that men less involved in such defensive events may leave the group sooner than those taking the lead, an inspiration could trigger gender-dependent responses to predators and alert calls.