Koko the "talking" gorilla whimpered with grief and "discussed" the death of her pet kitten, struck and killed by a car, for several days after getting the bad news, her teachers say.
The 13-year-old gorilla became famous after being taught American sign language by researchers at the Gorilla Foundation in Woodside, near Stanford University. The 12-year-old research project is said to be the world's longest continuing ape language study.
Koko, whose favorite picture book stories include "The Three Little Kittens" and "Puss 'n' Boots," asked for a kitten for a Christmas present a year ago, researchers said.
"But we gave her a life-like stuffed animal and she was terribly upset," said Ron Cohn, a biologist with the foundation. Koko refused to play with it and kept signing "sad."
So on Koko's birthday last July, she was allowed to choose a kitten from among several in a litter. She named the gray-and-white kitten "All Ball" as a joke, Cohn said. "The cat was a Manx and looked like a ball. Koko likes to rhyme words in sign language."
Koko, who has a full schedule of sign classes and other activities at the foundation, played with the cat for about an hour a day.
The two were on the cover of this month's National Geographic magazine.
After Koko was born at San Francisco Zoo, Penny Patterson, then a Stanford graduate student, began teaching her sign language as part of a thesis project. The project grew, and Patterson gained custody of the gorilla and organized the nonprofit foundation. Koko uses about 600 signs and has knowledge of 400 more, Cohn said.
The research work has had a few critics, some of whom believe that the gorillas are merely copying the researchers and have no concept of real language, Cohn said.
The kitten, which was rejected by its mother when it was 4 weeks old and was mothered by a terrier until it became Koko's pet, showed no fear of the 230-pound gorilla.
"They would play chase with each other and she (Koko) would hold it and pet it," Cohn said. "The cat reacted to her as she would a human, but she was pretty independent and would bite Koko or wriggle loose when she got tired of being babied."
When that happened, Koko would sign, "Obnoxious. Cat." by first pounding the wall and then running her hand across her cheek to designate whiskers, Cohn said.
The researchers were heartened by Koko's mothering instincts. She tried to nurse the kitten and was very gentle and loving, they said. She would often sign, "Soft. Good. Cat," while holding her.
In mid-December, All Ball wandered onto the highway near the seven-acre research facility and was run over.
"When we told Koko, she acted like she didn't hear us for about 10 minutes," Cohn said. "Then she started whimpering--a distinct hooting sound that gorillas make when they are sad. We all started crying together."
Koko then said, "Sleep. Cat." by folding her hands and placing them at the side of her head, Cohn said.