Female monkey fights off alpha male to take charge of 700-strong troop

A hard-fighting female macaque has assumed control of a 677-strong troop of monkeys in a nature reserve in southern Japan, a highly unusual development in the male-dominated simian world.

Yakei, a nine-year-old female macaque, began her rise to alpha status in April, when keepers at the Takasakiyama Natural Zoological Gardens, in the city of Oita, witnessed her attacking her own mother.

Not content with her new position as the dominant female in the larger of the nature reserve’s two macaque troops, she soon switched her attentions to Nanchu, the long-established alpha male. In late June, Yakei squared up to the 31-year-old Nanchu, who had been the undisputed leader for around five years, and saw her rival off with his tail between his legs.

Over the following month, keepers noted that Nanchu was careful to avoid Yakei, apparently out of fear of his 22lb assailant.

To test suggestions that Nanchu had been usurped, wardens carried out a “peanut test” in late June, leaving out nuts for the troop and observing which ate first. Zoo staff were surprised to find that Nanchu backed away from the food and permitted Yakei to eat first - a sure indication of her position in the troop’s hierarchy.

Keepers have also noticed a clear change in Yakei’s behaviour as she adopts the unmistakable characteristics of an alpha male macaque.

She has taken to walking with her tail held upright, a common trait in dominant males. Another new characteristic is climbing trees and violently shaking the branches, a demonstration of power among simians and considered to be extremely rare behaviour among females.

The park held a ceremony on July 30 to formally recognise Yakei’s assumption of control over the troop, with a member of staff dressed as a macaque accepting a commemorative scroll. Yakei was then encouraged to pull a length of cord to unveil a sign confirming her position as the alpha of the group and was rewarded with a banana.

Officials told the Mainichi newspaper that it was the first time that a female macaque had led a troop at the reserves since it first opened in 1953.

“Normally, female monkeys do not stand up against males”, Tadatoshi Shimomura, a zoo official, said. “I have no idea why she became number one. The world of macaques may be changing”.

The reserve has around 1,040 macaques in two troops, with the monkeys living in the densely forested mountain in the centre of the park. While the public is encouraged to “meet the cute baby monkeys” at the park, they are also warned not to get too close and to avoid making eye contact with the dominant adults.

There are believed to be more than 100,000 macaques across three of Japan’s four main islands, where they are often considered to be pests by farmers as they damage crops. They can also be aggressive towards hikers in rural areas, particularly when they are in a large group.