He may have been a bit standoffish with strangers, but Dar the chimpanzee never hesitated when playing with those he knew best.

“Dar was always up for a game of chase. That’s what I will miss in the morning: my morning exercise with Dar,” said Mary Lee Jensvold, director of the Chimpanzee and Human Communication Institute at Central Washington University, which holds “Chimposiums” every week for the public to learn about and interact with the resident chimpanzees.

Dar died suddenly Saturday morning of an unknown cause. At 36, he was by no means geriatric, Jensvold says, but about the age researchers are seeing male chimps die in captivity.

He was one of four chimps who came to the institute after learning sign language during an immersion project in the 1980s. Washoe, the first, died in 2007 and was recently honored in Ellensburg with the addition of a special statue and creation of the new Friendship Park. Moja died in 2002. The two remaining chimps at the institute are Tatu and Loulis, Washoe’s adopted son.

“They’re grieving today,” Jensvold said of the last two chimps. “They’re very quiet and seem a little morose ... They’re kind of doing the same thing that the rest of us are doing around here — staring off into space.”

All four chimps were originally raised by Allen and Beatrix Gardner at the University of Nevada in Reno, where the Gardners taught them American Sign Language and brought them up as they would human children. The chimps later went to live with Roger and Deborah Fouts, who founded the Ellensburg institute and served as its directors for many years.

Jensvold has been at the institute since 1986, and feels like she’s lost a member of her family.

“He was one of my best friends. I saw him every day, every single day, all day long,” she said. “I have a lifelong commitment to (the chimps) personally. They’re like children that are never gonna grow up and go away.”

She was with the institute when Washoe and Moja died, too, and says it doesn’t get any easier because each chimp is unique, and so are the relationships between the chimps and their handlers.

Dar was more reserved than the others, but “when he set his sights on being your friend, he was a fast friend,” Jensvold said.

She’s been reading Facebook posts on the institute’s page and has been amazed at the outpouring of love and support from people in the community who remember Dar, she said.

“He touched hundreds of people all over,” she said. “It’s a very difficult time for everybody here.”