Quote from Koko.org

Because of her unique ability to communicate with humans in sign language, Koko is a natural ambassador for endangered species, and thus we agreed to co-produce a short video PSA (Public Service Announcement) contingent on Koko’s willingness to participate.Turns out Koko was very interested in the subject, which we briefed her on via a recent issue of National Geographic titled “Cool It!” We also presented her with a script drafted by NOE (as any celebrity ambassador asked to do a PSA would expect) and allowed her to improvise during s series of brief daily video discussion sessions, in which Koko also had to learn a few new signs, such as “Protect” and “Nature.”

http://www.koko.org/