Leading behavior, positioning, and group spacing as indicators of dominance in Hapalemur griseus
Irwin, Mitchell T.
M.A. (Master of Arts)
Department of Anthropology
Social hierarchy in animals; Lemur (Genus)--Behavior; Lemurs--Behavior; Primates--Behavior
Female dominance is a rarely occurring behavioral trait across mammals but a trait that is commonly observed in Malagasy lemurs. On the other hand, intersexual dominance dynamics are only known for 36% of all lemur species, being best documented in species with high rates of agonism, such as ring-tailed lemurs (Lemur catta). Other social cues such as leadership during group movements and positioning within the social group can be used to determine dominance, but few lemur studies have utilized these behaviors to test for dominance. In this study, I quantified intersexual relations in bamboo lemurs, Hapalemur griseus griseus, an herbivorous lemur with a diet that consists largely of bamboo and displays low rates of aggression. Three groups were studied, one from continuous rainforests, and two from disturbed rainforest habitats. Animals of both sexes and multiple age-sex classes were observed during the study period of June-August 2014. I recorded group movements, acts of aggression and displacement, grooming, feeding activity, spatial location within the group (central or peripheral), and dyad distances. All of these data were analyzed in an attempt to determine if H. griseus maintains dominance using social cues rather than by acts of aggression. Dominance status could not be determined for the group living in continuous rainforest due to small sample size and greater group complexity. In discontinuous forest the smallest group studied (MAHA-2) did demonstrate a clear trend towards female dominance, while the other group (MAHA-3) did not. First, the adult female in MAHA-2 was found to be more centrally located in all social settings compared to the adult male. Second, the adult female in MAHA-2 led group movements more often than all other group members, with other group members successfully following her the majority of the time. In contrast, the MAHA-3 group did not demonstrate female dominance at all, but this may be related to the disappearance of an adult female group member shortly before my study. This project did demonstrate that female dominance exists within H. griseus, but it is unclear if all groups follow a female-dominant social structure. Intersexual relations in this species may be variable among groups, perhaps in response to group size and/or local ecological conditions. More research is necessary to determine if female dominance is ubiquitous in bamboo lemurs, or if dominance is more flexible in this species.
Foreit, Kimberly, "Leading behavior, positioning, and group spacing as indicators of dominance in Hapalemur griseus" (2016). Graduate Research Theses & Dissertations. 3776.
vii, 93 pages
Northern Illinois University
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Advisors: Mitchell T. Irwin.||Committee members: Dan L. Gebo; Leila M. Porter.||Includes bibliographical references.||Includes illustrations.