A Statistical Analysis of the Social Behavior of the Male Stumptail Macaque(Macaca arctoides)
Discussion Page 8

Title/summary page


Page 1


Materials and Methods
Pages 2 - 3


Pages 4 - 5 - 6 - 7


Pages 8 - 9


Page 10


Page 11


Figures 1- 8
Figures 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8


Tables I-IV
Tables I - II - III - IV

The correspondence of the behavioral repertoire of our animals to that observed by Bertrand [1969] and Chevalier-Skolnikoff [1974], including the repertoire of animals under field conditions, suggests that we can make generalizations concerning the behavior of adult male stumptail macaques to conditions beyond the restricted laboratory setting of this study. Also supporting this contention is the fact that most of the behaviors seen in this study were shown by all of the animals in a particular category, ie, all dominant animals usually showed all behaviors characteristic of dominants, and both subordinates showed the behaviors characteristic of subordinates.

The frequencies of social behaviors were much higher than one would expect under colony or field conditions. The frequencies were deliberately enhanced by our technique, which sampled behavior sequences from the first few minutes of confrontations between animals that spent most of their time under conditions of restricted social interaction. It is obvious from Figure 4 that the social behavior literally "exploded" during the first minute in the confrontations, with sexual, offensive, and defensive or submissive behavior occurring in as many as 50% of the tests. One had the feeling, in watching the animals, that the individual housing conditions had created a kind of "social deprivation" and a necessity for the reassertion of dominance status as soon as they encountered each other. Although the rates of intermale sexual behavior are higher than under natural conditions, it should be noted that rhesus macaque males, under field conditions, engage in mounting of males almost as often as mounting of females [Altmann, 1962].

Generalizations from our findings to the species as a whole is limited by certain physical aspects of the test situation. Because of the small size of the test cage, the animals were unable to flee for any great distance when attacked. Under field conditions, one might expect chases of up to a hundred yards which might then be reversed [cf. Rowell, 1967]. Further, by restricting our observations to pairs of animals, we precluded the analysis of more complex triadic relationships that may be crucial in the development of social structure and role among primates. In the stumptail macaque, such triadic relationships include the enlisting of aid of another animal during a fight. [Bertrand, 1969] and the harassment during sexual behavior of another pair [Gouzoules, 1974]. Progress in the ethological analysis of triadic relationships within a laboratory setting has been made by Maxim (1978b) working with Macaca mulatta. Triadic relationships may be crucial for the ontogenetic development of social structure of macaques, in which the adult dominance hierarchy often reflects the dominance hierarchy of their mothers [Sade, 1967]. This may be mediated in part by the "third party" intervention of mothers into disputes that involve their offspring, a phenomenon that continues to occur even after their offspring have grown into adulthood [Sade, 1972].

The methods and results of this study are most comparable to those of the study by Van Hooff [1973] on chimpanzees. By transforming his Figure 44 so that vocalizations and facial expressions are treated as separate channels of communication and comparing it to Figures 4 and 5 of the present study, it is possible to see clearly the similarities and differences in the results of the two studies.

Of the eight categories distinguished by Van Hooff by means of cluster analysis of the chimpanzee data (aggression, submission groom/contact, male sex, play, juvenile contact, bluff, and excitement), four are readily distinguishable in our data: aggression, submission, groom/contact, and male sex. Two are conspicuously absent: play and juvenile contact. Two others are problematical and warrant further discussion: bluff and excitement.

The absence of behaviors corresponding to play and juvenile contact in our data is not surprising. Bertrand [1969] noted that among stumptail macaques, play is shown primarily by infants and juveniles, rather than by adults, while many authors have noted that chimpanzees are noted for the high frequency of play by adults.

The category of aggressive behavior in Van Hooff corresponds to offense in the present study. One difference was the absence of vocalization during offense in the stumptail, although it should be noted that in the closely related rhesus macaque, Altmann [1962, 1965] has described a "!ho!" vocalization associated with attack.

(Continued on next page)

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