World's oldest captive rhesus monkey dies aged 43 at Kyoto City Zoo

KYOTO -- The world's oldest rhesus monkey kept at Kyoto City Zoo died on Sept. 12 at the age of 43 years and four months, the zoo has announced.

Rhesus macaques are considered to have lived a long life even at age 30, and their average lifespan in the wild is about 15 years.

The female macaque, named Isoko, had been certified by the Guinness World Records in 2020 as the "oldest living rhesus macaque/monkey in captivity," and she renewed her own record this year when she turned 43 on April 15.

Isoko had been living in an air-conditioned "nursing home" set up in the Great Ape House at the zoo in Kyoto's Sakyo Ward with her sister Beat, 36, and her good female friend Gongo, 31, since November 2016, apart from a troop kept on "monkey island." Though she had been spry despite stooping with old age and moving precariously, her condition began to rapidly deteriorate around mid-July this year to levels where she could no longer peel a banana -- her favorite food. She would drop the bananas and give up eating.

According to 33-year-old zookeeper Haruna Bando, who was in charge of caring for Isoko, the monkey's condition briefly recovered after she was given an oral rehydration solution and nutritional supplements because she could not eat enough herself, but she lay down during mealtime on Sept. 7, and started breathing rapidly. She was transferred from the nursing home to a "hospitalization room" at the zoo on the evening of Sept. 10, and was administered oxygen therapy. However, she apparently could no longer drink solution on Sept. 11, and her death was confirmed in the early morning of Sept. 12. An autopsy found that the cause of death was congested heart failure due to a lung tumor.

Isoko liked to spend her time outdoors, and she was sometimes taken outside in a pet carrier.

"Even after we almost lost hope, she recovered many times," Bando said about Isoko's death. "We were able to support Isoko without pressing our desire for her longevity. We saw Isoko's tremendous vitality."

As the zoo is temporarily closed due to the coronavirus state of emergency, it is not accepting offerings such as flowers. The operators of the zoo are considering holding a memorial service for Isoko after the facility reopens.

(Japanese original by Yoko Minami, Kyoto Bureau)