One of the St. Louis Zoo's most popular orangutans, and its oldest primate, has died.
Zoo officials said "Junior" was euthanized Tuesday after his health had been declining. He was thought to be about 44 years old.
Junior was the third-oldest male in the national Orangutan Species Survival Plan population.
Zoo officials said Wednesday that veterinarians had been treating Junior for severe arthritis for three years. In recent weeks, pain medication did not appear to be helping and Junior became reluctant to move and eat.
"It's like losing a really close friend. They share so many characteristics with us and we developed very close bonds," the zoo's primate curator Ingrid Porton said. "It's a very difficult decision to make, but I think we made the right and kind decision."
Junior was born in Sumatra, a western Indonesian island, and came to the U.S. in 1963. He first lived at the Tulsa, Okla., and Memphis, Tenn., zoos.
He came to St. Louis in 1992 as part of the national species survival plan and quickly became a favorite among zoo keepers for his gentle nature.
"You had to prove yourself to Junior and show you were trustworthy," Porton said. "When he let you in his world, you saw what a magnificent guy he was. You wouldn't say that about his female counterpart or some other male orangs."