at the time, habituation of chimpanzees was typically done by means of food provisioning. nishida first tried sugar cane, until he found that bananas worked better. he developed a "mobile provisioning" technique, in which scientists announced their presence to distant chimpanzees by imitating the species-typical hooting calls, after which the apes would approach and obtain food. this way, their normal roaming patterns remained intact, as they never attached themselves to a fixed feeding site. after the feeding session, the investigators followed the apes for the rest of the day.