MILWAUKEE (CBS 58) -- The Milwaukee County Zoo has announced the death of Patti, a 55-year-old river hippopotamus who was humanely euthanized on Sunday, Nov. 10. Patti had been a resident of the zoo for over 50 years, arriving from the Dallas Zoo in 1972.

According to a Thursday, Nov. 14 press release from the zoo, Patti appeared lethargic and showed reluctance to leave her indoor pool on Saturday, Nov. 9. She refused her evening meal, leading the animal care team to closely monitor her.

Later that night, Patti’s condition reportedly rapidly declined, and the decision was made to euthanize her. She passed away surrounded by her caretakers, who comforted her in her final moments by rubbing her ears and feet.

At 55, Patti was considered geriatric, surpassing the median life expectancy of 36.7 years for female hippos in human care, according to the Association of Zoos and Aquariums. 

The zoo says that Patti was known for her spirited personality and fondness for fruits like cantaloupe and watermelon, also noting that she often engaged with visitors, especially children, by approaching the viewing windows of the Dohmen Family Foundation Hippo Haven.

Patti also participated in behind-the-scenes tours and contributed to research projects aimed at improving care for her species.

Her legacy will continue as biofacts from Patti will be donated to the U.S. Fish and Wildlife Service Forensics Laboratory to aid in wildlife trafficking investigations. The river hippopotamus is listed as Vulnerable by the International Union for Conservation of Nature due to threats from poaching and trophy hunting.

Hippo Haven is now closed for the season and is expected to reopen in the spring, featuring Happy, the zoo’s remaining male hippo. Construction on a new indoor and outdoor habitat for rhinos and a new indoor space for hippos is scheduled for completion in fall 2025.

The zoo says it will consider acquiring another hippo at that time.