Analyzing the hierarchical relationships for a group of Sciurus granatensis (Mammalia: Rodentia:Humboldt, 1811) in Caracas, Venezuela

Abstract

Social relationships within mammalian groups involve the development of hierarchical relationships among their members to avoid conflict. This hierarchy is established through aggressive dyadic encounters. Therefore, one way to determine if a hierarchy exists is to quantify the aggression-submission interactions and the movements between pairs of individuals. Here, we studied the social interactions in a group of Sciurus granatensis located within an urban forest patch in the city of Caracas, Venezuela, in order to determine the existence of a dominance hierarchy during their visits to the available artificial feeder. Also, we propose a non-invasive identification method to the identification of individuals based on morphological characters. The individuals were filmed for 19 consecutive days, from their resting areas to the trough. Interactions were analyzed using focal observation and exploration methods, which were subsequently described on an ethogram and classified into displacement (intimidation and withdrawal) and aggression (attack and attack with persecution). Overall, 19 individuals were identified within the group and 156 (with a daily average of 8.2 ± 4.3) interactions were recorded for 11 of them. The most common form of interaction was intimidation. Moreover, it was found that there were residents and occasional visitors in the group. The existence of dominance was determined with a Landau linearity index (h = 0.636). Two individuals shared the highest hierarchical rank. We observed a significant inverse correlation between tail thickness and the social rank. We concluded, based on the non-invasive identification system proposed, that there is a linear hierarchy in the group.