Mondo, a 44-year-old Southern white rhino at the Knoxville Zoo whose legacy to his endangered species included siring nine offspring, was been put down after his health began to fail.
Zoo Knoxville officials decided to have him euthanized Thursday afternoon.
Mondo's health had been slipping. Caretakers and a veterinary team at the University of Tennessee College of Veterinary Medicine treated him but he did not rally.
His keepers were with him when he died, according to the zoo.
The rhino, among the senior residents at the zoo, came to Knoxville to May 1988, according to the zoo, to be paired with the zoo's females. He was believed to have been born in the wild and then caught, eventually ending up in the United States.
Mondo fathered nine calves, which are now at other zoos as part of the Species Survival Plan, a formal preservation effort among zoos.
The rhino was considered a zoo "ambassador," and even after he no longer took part in breeding he remained on exhibit. The white rhinoceros, of the African grasslands, typically lives 40 to 50 years.
Lisa New, zoo president and CEO, said in a statement the animal was "beloved."
“He connected people with the plight of wild rhinos," her statement reads. "His legacy lives on not only in his progeny, but also in all those who were touched by him to care about the survival of rhinos.”
Southern white rhinos neared extinction in the late 19th century.
Preservation efforts have helped, but the animals still are favorite hunting targets because of the market value of their horns.
