Dinâmica social e movimento coletivo em éguas (Equus caballus)

Abstract

This study analyzes the social dynamics of a group of mares in three dimensions: dyadic, triadic, and collective. It is divided in three chapters which objectives are: 1) describe the dyadic affiliative and agonistic interactions and characterize the social dynamics of preferable partnerships; 2) analyze the occurrences and interactions in conflict (third part interventions) and post-conflicts (reconciliation, consolation, and appeasement); and 3) characterize collective movement dynamics under analyzes of individuals features (age, weight, rank, and reproductive state).The study was carried out at Volta Haras (Frei Paulo, Sergipe, Brazil) in 2012 and 2013. A group of 64 mares and 21 suckling foals of manga-larga marchador breed were observed. Three daytime methods of behavioral records were employed: 1) continuous animal-focal (registering occurrence of agonistic and affiliative behaviors, synchrony and change of direction) totaling 130 hours; 2) all occurrences of conflict in 304 hours; and 3) scan (position and activity) totaling 117 scans which generated closeness information (value of the relationship), social network, and distance among the animals. In the first chapter, we describe that the mares were more involved in affiliation than in agonisms. We suggest that synchrony in direction is a kind of affiliation in this species. Older and heavier mares had higher ranks, but there was not a category that was more aggressive than the other. Preferable partners presented similarities in age, weight, strength in the relationships, and social centrality, being the social dynamics of these partnerships characterized by closeness and low agonism among the partners. In the second chapter, we report that reconciliation, comfort/appeasement, and intervention in conflicts (IC) occurred in 57%, 37%, and 31% of the conflicts, respectively. The occurrence of reconciliation or dispersion may be strategies to reduce the social uncertainty/instability post-conflict. The conflicts occurred between mares with low closeness, and reconciliation was not dependent on the value of the relationship (friendship), but the comfort and appeasement did were. The intervention in conflicts were performed by mares with higher rank and age than the opponents of the conflict, and it was not directed to preferable partners, suggesting maintenance of the social stability. In the third chapter, we detected that there was not a category of individuals that positioned themselves to the center of the herd with higher frequency. Older mares tend to be ahead of the group. Younger animals (foals) were socially more central and animals with differentiated nutritional needs (pregnant mares and suckling ones) and high rank were less socially central. More than half of the herd was directed, with anticipation, to the direction that the group started to follow, and the agreement index in the direction (AID) was higher when the group moved more. This may suggest that the direction of the group’s movement was determined by the direction of the body of the majority of the animals (minimizing consensual costs), which may have occurred by the mimetic synchronization process, suggesting a simplified way of coordination (leadership) distributed in grazing. Empty and low rank mares adjusted more their directions in grazing towards the other mares. This indicates more occurrence of mimetic process of synchronism, which may lead to the coordination of the movement to be performed by animals that keep more consistency in direction or older animals.