Macaques at Japan reserve get first alpha female in 70-year history

By Gavin Blair

In a rarely seen phenomenon in the simian world, a nine-year-old female known as Yakei has become the boss of a 677-strong troop of Japanese macaque monkeys at a nature reserve on the island of Kyushu in Japan.

Yakei’s path to the top began in April when she beat up her own mother to become the alpha female of the troop at the Takasakiyama natural zoological garden in Oita city. While that would have been the pinnacle for most female monkeys, Yakei decided to throw her 10kg weight around among the males.

In late June, she challenged and roughed up Sanchu, the 31-year-old alpha male who had been leader of “troop B” at the reserve for five years.

Surprised wardens at Takasakiyama, where there has never been a female monkey boss in the reserve’s 70-year history, carried out a “peanut test” on 30 June, putting out nuts for the group and seeing who ate first. Sanchu backed away and gave Yakei first dibs on the treat, confirming her alpha status.

“Since then, Yakei has been climbing trees and shaking them, which is an expression of power and a very rare behaviour in females,” Satoshi Kimoto, a guide at Takasakiyama, told the Guardian.

“She has been walking around with her tail up, which is also very unusual for a female,” added Kimoto, who said that staff at the reserve were at a loss as to the causes of Yakei’s dominant antics.

Takasakiyama, established as a reserve for monkeys in 1952, is home to about 1,500 macaques, split between troop A and troop B. The monkeys live mainly in the forested mountain at the centre of the reserve, roaming freely and coming down to lower ground for food provided by wardens.

The wild population of Japanese macaques is estimated to be more than 100,000 and widely spread across three of Japan’s four main islands: Kyushu, Honshu and Shikoku.

They are known to sometimes be aggressive, and hikers, mountain climbers and visitors to the Takasakiyama reserve are advised not to maintain eye contact with them as it is interpreted as a challenge.