Hanabiko "Koko" (July 4, 1971 – June 19, 2018) was a female western lowland gorilla. Koko was born in San Francisco Zoo, and lived most of her life at The Gorilla Foundation's preserve in the Santa Cruz Mountains. The name "Hanabiko" is of Japanese origin and is a reference to her date of birth, the Fourth of July. Koko gained public attention upon a report of her having adopted a kitten as a pet and naming him "All Ball", revealing her alleged ability to rhyme. Her instructor and caregiver, Francine Patterson, reported that Koko had an active vocabulary of more than 1,000 signs of what Patterson calls "Gorilla Sign Language". This puts Koko's vocabulary at the same level as a three-year-old human. In contrast to other experiments attempting to teach sign language to non-human primates, Patterson simultaneously exposed Koko to spoken English from an early age. It was reported that Koko understood approximately 2,000 words of spoken English.