MCZ Regrets to Announce the Death of Silverback Gorilla

Posted Date

September 14, 2023


Animal Updates, In The News

It is with very heavy hearts that the Milwaukee County Zoo announces one of its male silverback gorillas, Oliver, died Sept. 13. He would have turned 35 years old on Oct. 7. Oliver, along with two female western lowland gorillas, Dotty and Nadami, arrived at MCZ in 2021 from the Columbus Zoo and Aquarium.

Oliver had been experiencing several chronic health issues for many years, which were being treated on an ongoing basis by the Zoo’s animal care team. On Sept. 13, Oliver was anesthetized to address an infected tooth that was causing him pain.

While Oliver was under anesthesia, he experienced cardiac and respiratory arrest. The animal care team worked tirelessly to revive him, including administering medications, intubating, and performing CPR. Unfortunately, the attempts were unsuccessful. A full necropsy (animal autopsy) will be conducted, and initial results are expected in the next few weeks.

According to the Association of Zoos and Aquariums (AZA), the median life expectancy of a male silverback gorilla living in human care is 32.7 years. At 34 years old, Oliver was considered a geriatric animal. For more than 10 years, Oliver had chronic heart disease, as well as other chronic illnesses including hypothyroidism, arthritis, dental disease, and gastrointestinal disease. Treatment for all these diseases was ongoing, and he received regular veterinary checkups to monitor his cardiac and gastrointestinal health. These checkups included echocardiograms, CT scans, and endoscopic procedures.

Oliver, Nadami, and Dotty lived together as a family unit at MCZ, with Oliver serving his role as the silverback and the leader of the troop. Even though he was hearing impaired due to an illness when he was young, he communicated well with his troop.

The care team gave Nadami and Dotty the opportunity to see Oliver after he died, and with his passing, Dotty and Nadami will choose what they need. They may choose to be in the public habitat in the Stearns Family Apes of Africa building or to stay in the non-visible holding areas. Whatever the choice, zookeepers will give them extra love and attention, and make sure they know they’re safe and cared for.

Zookeepers share that, “Oliver was a well-loved gorilla by the teams at the Milwaukee County and Columbus Zoos alike. He was intelligent and very intuitive, which helped him live a full ‘gorilla social life’ even after it was discovered he was deaf. He did a great job of leading and protecting his troop of females. He will be missed by many!”

Western lowland gorillas are listed by the IUCN (International Union for Conservation of Nature) as critically endangered due to loss of habitat, poaching, illegal pet trade, and illegal commercial bushmeat trade. The loss of Oliver is great, and he will be mourned by his caregivers, Zoo guests, and volunteers. Help support Oliver’s legacy by learning more about gorilla conservation efforts at