DOMINANCE RELATIONSHIPS AND AGGRESSION OF FOALS (EQUUS-CABALLUS)

A herd of 15 Belgian brood-mares and ten foals located at the Snyder Foundation Equine Research Center in Athens, Georgia was studied. Field data were collected using 30-min focal samples, such that 1 h of data was collected on each foal per week of its life. Social spacing was recorded at 2-min intervals. Social encounters during the focal sample were recorded on cassette tapes and later transcribed. The specific aspects of social structure studied were dominance-subordinance relationships, preferred associates, social spacing, aggression rates, the frequency of aggressions administered down the dominance hierarchy, and interactive play bouts. The rank order of the foals, both before and after weaning, was positively correlated with the rank order of their dams (Spearman's rho, P<0.02). There was also a significant relationship between a foal's rank and its total aggression or aggression rate per subordinate post-weaning. Higher ranking foals had higher rates of aggression (P<0.005). Over 80% of threats were directed down the dominance hierarchy. The play-rank order of the foals, scored by the number of times a foal left a play bout, was not significantly correlated with the rank order as scored by agonistic interactions (P>0.99).