“…It might be because most primate species have strong social bonds among group members. Group members frequently exchanged social behaviors (social grooming: Goosen, 1981, vocal communication: Wang, 2000Sugiura, 2007) and keep proximity to one another even in foraging (Pastor-Nieto, 2001). Then, individuals often leave food patches to follow other group members or gave up patches due to aggressive behavior by dominant individuals (Nakagawa, 1990).…”