Rank, relationships, and responses to intruders among adult male vervet monkeys

Abstract

We examined the influences of dyadic relationships among captive adult male vervet monkeys (Cercopithecus aethiops sabaeus) on behavior directed toward caged "intruder" males placed inside subjects' enclosures. Subjects were all 9 adult male residents from three stable social groups, each of which contained 3 adult males, at least 3 adult females, and their immature offspring. Every male was observed in two 3-hour sessions, each time with one of the 2 other adult males from his group. Observation sessions consisted of six consecutive 30-min stages in which group composition and the presence of the intruder were manipulated. All groups exhibited a stable, linear male dominance hierarchy prior to and throughout the study. In each group, there was one pair of males, when together, in which each member exhibited higher rates of intruder-directed approach and aggressive behaviors than when either animal was paired with the third male of his social group. Such pairs were also distinguished by high levels of within-pair agonistic interactions. The higher-ranking member of each dyad was the most aggressive male toward the intruder in his social group, although only one of these animals was the dominant male of his group. Mutual facilitation of aggression against intruding males is interpreted as cooperative behavior benefitting both males by increasing the likelihood of repelling a potential competitor for resident females. Such cooperation provides further evidence in nonhuman primates for cohesive male-male dyads between animals whose social interactions are characterized by agonism. o 1993 Wiley-Liss, Inc.

Determinants of immigration strategies in male crested macaques (Macaca nigra)

“…In this situation, subsequently immigrating males may experience reduced costs, since male-male cooperation against intruders may be reduced; and within group male-male aggression increased 29 when resident males have to consolidate their position within the group. Evidence for such a scenario derives from vervet monkeys ( Chlorocebus aethiops sabeus ) 32 .…”

Individual differences in response to a stranger: Social impulsivity as a dimension of temperament in vervet monkeys (Cercopithecus aethiops sabaeus).

“…This test is a variant of the resident–intruder paradigm that is commonly used to measure aggressiveness in rodents (Hahn & Schanz, 1996; Kemble, 1993). Resident–intruder paradigms have been used in prior studies of nonhuman primates to assess group differences in behavior based on the characteristics of the resident or stimulus animals, such as sex or familiarity (French, Schaffner, Shepherd, Miller, 1995; Mendoza & Mason, 1986; Schuster, Raleigh, McGuire, & Torigoe, 1993). Here, the Intruder Challenge Test has been developed to measure individual differences in temperament.…”

Continuity versus (political) correctness: Animal models and human aggression.

“…Although physical attack is extensively used by both humans and nonhuman mammals, primate behaviors appear t o provide a bridge between the largely direct and individual physical nature of aggression in most mammals and its more subtle manifestations in people. For example, in captive vervet monkeys, group males may show mutual facilitation of aggression toward intruding males, interpreted as coopera-tive behavior in repelling competitors for the group females (Schuster, Raleigh, McGuire, & Torigoe, 1993). Also, among free-ranging olive baboons, dominant males may or may not be the most aggressive animals of the group, and dominance is often maintained by stratagems other than direct attack (Sapolsky, 1990).…”