Date of Award:

5-1-1971

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Biology

Department name when degree awarded

Zoology

Committee Chair(s)

Keith L. Dixon

Committee

Keith L. Dixon

Committee

David F. Balph

Committee

LeGrande Ellis

Committee

James A. Gessaman

Abstract

Agonistic postures of Red Jungle Fowl hens were studied during initial pair encounters, and during the introduction of strangers into established flocks, using time and motion analysis of motion picture films. The posture of each hen was quantitatively determined by measuring the angles of the trunk, neck and tail to the horizontal. These three measurements were added to obtain a posture index. Comparisons were made of postural measurements for the same individual in contests which it won and in contests which it lost. No statistically significant difference could be demonstrated, but a trend for the neck angle and posture index values to be higher in the winning situation was present. A similar comparison for final posture showed highly and very highly significant differences for most of the hens. The neck angle and the posture index were the most useful for separating the winning and losing postures. The neck angle and the posture index showed highly significant differences for the initial postures of the winners and losers within the same contest. Therefore, it is possible to predict the outcome of the encounter by measuring the postures of the contestants at the beginning of the contest. A comparison of the final postures of winners and losers revealed very highly significant differences for all postural measurements. The posture index in contests won showed a direct correlation with the number of contests won, again suggesting that the posture index is an indicator of ability to win encounters. Contests between each pair of hens were repeated on three successive days, and the latency to the first interaction for each hen over the three sets of contests was examined. There was a significant decrease in latency from the first set of interactions to the second, followed by an increase in the third. Following the initial pair encounters, the hens were divided into two flocks of approximately equal aggressiveness levels, and the dominance order in each flock was determined. There was general agreement between the measure of fighting ability obtained in the paired encounters and in the social order of each flock. Strange hens (members of a different flock) were introduced daily into the established flocks of five and six individuals respectively. The resulting interactions were recorded and the posture of the introduced hen was filmed and measured. There was a significant difference between the posture index of the same individual when introduced into a strange flock, and the same measurement made when reintroduced into its home flock. Considerable variability in success in attaining rank in the social order of the strange flock was observed among the hens. The lowest ranking member of one flock was able to dominate all members of the other flock when reintroduced into it. (This finding was confirmed upon replication.) These results indicate that postures of hens are useful as indicators of aggressiveness. That is, they can be used to predict the outcome of encounters. The first encounter between two hens does seem to result in a permanent dominance-subordination relationship between them, even under controlled conditions, since only one reversal of dominance occurred out of 55 pairings. Willingness to begin an encounter, as measured by the latency to the first interaction, also correlates with ability to win encounters. Differences in posture are also noticeable when the same individual is introduced into "strange" and "home" flock situations. Finally, the supposed advantage of an established flock over a single introduced hen does not seem to hold consistently for small flocks of Red Jungle Fowl.

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