A Statistical Analysis of the Social Behavior of the Male Stumptail Macaque(Macaca arctoides)
Materials and Methods Page 2

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Materials and Methods
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Figures 1- 8
Figures 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8


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

The subjects were six adult male stumptail macaques (Macaca arctoides) that had been housed in individual cages for two years prior to and during the study. In preliminary tests the animals had been paired and dominance relations, indicated by consistent tendency to attack or submit, had been established. One monkey was subordinate on all occasions to the other five, one monkey was subordinate to four others, but consistently dominant to the first. The other four showed attack and never submission. Canine teeth had been cut down to reduce damage inflicted during biting, and each monkey had a collar around the neck attached to a 1.5-m steel cable to facilitate handling. The monkeys were never punished or restrained roughly.

Tests consisted of encounters between two males. They were conducted in an empty wire mesh test cage 2.7 m by 5.4 m by 2.7 m high. Animals were transferred from home cage to test cage in a wheeled carrying cage, and they moved voluntarily from cage to cage or were coaxed to move by food rewards. The subordinate male was always placed first in the test cage. Behavioral recording began as soon as the dominant male entered the cage.

Forty tests were conducted, including 32 dominant-subordinate pairings and eight dominant-dominant pairings. This included all nine of the possible logical combinations of dominant-subordinate pairings, most of them conducted 3-4 times. Because of the severity of the fighting, only two of the possible combinations of dominant-dominant pairings were done, each of them four times. Because most of the very active social behaviors occurred in the first few minutes of testing, it was decided to limit most of the tests (28 tests) to five minutes in duration. However, to get some idea of the behaviors in longer tests, 12 tests, including at least one of each animal combination, were conducted for 20 minutes.

Every behavior of both animals was recorded sequentially on a strip of moving paper with a speed of one 1 m/minute. Two observers (the authors) worked simultaneously; one scored acts and postures of both monkeys; the other scored vocalizations, eye contact, lip retraction, and mouth opening. Time markers inserted each minute were used following the test to line up the acts and postures on one tape with the date recorded on the other tape, and they were also used to block the data for minute-by-minute analysis.

Scoring of acts and postures corresponded closely to the behavioral repertoire described by Bertrand [1969] for the stumptail macaque. Those which occurred five or more times are listed (along with vocalizations and facial expressions) in Table I, along with a comparison to Bertrand's terminology.

Facial expression was scored in a manner that did not assume a motivational context, unlike the technique of Bertrand [1969]. Dynamic expressions, lipsmacking face and teeth chattering face, were scored as in Bertrand [1969]. Static expressions were scored in terms of mouth opening and lip retraction; mouth opening on a scale from 1 (closed) to 4 (yawning) and lip retraction on a scale from 0 (puckered lips) to 3 (teeth and gums maximally exposed).

Two basic data sets were prepared, one more inclusive than the other. Both sets consisted of an obligatory alternation of acts and postures between the two monkeys. If one monkey changed its behavior and the second monkey did not, then we repeated the preceding notation for the second monkey. For this reason, certain activities or postures such as grooming, sitting, or lying were often repeated in the data set, because during the time one monkey maintained the posture, the other monkey had changed its behavior. Each act or posture was accompanied by notation for simultaneous eye orientation, facial expression, and vocalization or mouth movement. The more inclusive data set included repetition of the same acts and postures in those cases when the only change in succeeding behavioral events was in eye orientation or facio-vocal activity; a less inclusive data set consisted of alternation of acts and postures in which each successive behavioral event included a change in act or posture. In other words, the time frame of the latter was determined by the rate of change in acts and postures, while the time frame of the former was determined by the rate of change of acts, postures, facial expressions, and vocalizations. The less inclusive data set was then arranged into two data matrices, consisting of two 30 x 30 tables. The 30 behaviors that occurred five or more times in the study were listed on the axes of the matrices. In one matrix, behavioral transitions were entered in terms of dyadic sequences (i.e. one act or posture followed by another) within the monkey, and in the other matrix, behavioral transitions were entered in terms of dyadic sequences between the monkeys. There were 3813 entries in the within-animal matrix and 3864 entries in the between-animal matrix. Difference in the totals is due to the fact that the first and last behaviors in the within-animal sequences had no antecedents and consequents, respectively.

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