From the Sequoia Park Zoo:

Sequoia Park Zoo staff sadly announce the passing of one of our oldest and best known zoo animals, our female White-handed gibbon Joh-leen. She had been under intensive veterinary treatment since December of last year for a series of health problems. With the help of the amazing veterinary team at UC Davis Veterinary Hospital and our zoo veterinarian, along with our dedicated animal care staff, she was treated successfully for these conditions and seemed to be on the road to recovery. Unfortunately, she developed a new life-threatening condition in the last couple of months and despite our best efforts to save her, Joh-leen passed away yesterday during an emergency procedure.

Joh-leen and Bono

Joh-leen was born at Sequoia Park Zoo on July 12, 1982 and was reared by zoo staff after the death of her mother when she was an infant. In 1985 she was paired with her lifelong mate Bono and they have remained a closely bonded pair ever since. Zoo visitors for the past 4 decades have delighted hearing the two sing their pair-bonding duets most every morning, which often included Joh-leen showing off her remarkable acrobatic skills. The pair could be seen grooming and playing together every day. She will be sorely missed by her mate, her loving animal keepers and volunteers, and by visitors who came to know and love her. Those who wish to leave remembrances of Joh-leen are welcome to do so at the Zoo’s gibbon exhibit.

Zoo officials are working with the national Species Survival Plan program, which coordinates a cooperative captive breeding program among The Association of Zoos and Aquariums accredited zoos, to find a suitable new mate for Bono. Gibbons under human care generally live relatively long lives, on average 40 years, with longevity records of 57 years old. White-handed gibbons are endangered in their wild habitats in Asia, primarily due to habitat loss from human activities such as logging, and agriculture including palm oil plantations. The Zoo’s gibbons and other animal ambassadors help connect people to the wonder of wild animals and promote their protection for future generations.