Starting from scratch: A first look at a "displacement activity" in group-living rhesus monkeys.

Data on scratching behavior were collected from a group of rhesus monkeys living in spacious surroundings. Juveniles scratched more often than adults. Adults scratched most often in social contexts and in close temporal association with a change of behavior. Subjects of intermediate dominance rank, in particular, scratched around the time of a behavioral change, and these subjects were the only ones to show increased scratching during tests involving restricted access to food (thwarting or frustration). The outer thighs, lower back, and sides were the sites scratched most frequently, not necessarily matching sites reported to be preferred for self-grooming. Scratching in monkeys has certain characteristics in common with some well-studied displacement activities in other species, and it possibly also serves as a signal that the individual is preparing to change behavior.