Chantek, an orangutan who communicated with researchers using sign-language, has died at Zoo Atlanta.
He was 39, making him one of the oldest male orangutans living in captivity in North America.
Zoo Atlanta says Chantek died Monday. Cause of death isn't known, but the zoo says veterinarians had been treating him for progressive heart disease.
As part of that treatment, Chantek underwent an array of tests, including the first voluntary echocardiogram performed on an awake orangutan.
“He also participated in voluntary blood pressure readings, blood draws, all sorts of things,” said Jennifer Mickelberg, Senior Director of Collections and Conservation at Zoo Atlanta.
“Those sorts of training activities that are husbandry-based allow us to take much better care of the animals and understand their health status and how we can provide treatment.”
Chantek came to the zoo in 1997 at the age of 19. He was born at Atlanta's Yerkes National Primate Research Center and spent nine years living with researchers at the University of Tennessee-Chattanooga.
Researchers raised him like a human child and taught him at least 150 words in American Sign Language. He also learned other human skills such as using a bathroom and cleaning his room.
“The most common types of signs that Chantek used was when he wanted to go outside or wanted to have a blanket or water or juice. He mostly used sign to communicate what he wanted,” Mickelberg said.
Zoo Atlanta says Chantek was given a "naturalistic" living environment with other orangutans once he arrived there.
A post-mortem exam of the ape is scheduled to be performed, with results expected in a few weeks.