Dominance and "Fall Fever": The reproductive behaviour of semi-free-ranging Male Brown Lemurs (Lemur Fulvus)

Abstract

Lemur fulvus, the brown lemur, is a cat-sized arboreal prosimian, native to Madagascar and the island of Mayotte, in the Comoro Archipelago. A social prosimian, ~ fulvus typically forms cohesive troops of from 5-15 individuals. Troop composition is usually reported to be at, or near, a 1:1 sex ratio. The problems examined in this thesis were chosen in order to address aspects of L. fulvus social dynamics that are unclear, given the depiction of L. fulvus social behaviour presented in the primate literature. What are adult males doing, in the reported absence of agonistically-determined dominance hierarchies, to gain and maintain access to estrus females? Given the breeding season behavioural changes and fluctuations exhibited by adult males (a behavioural complex here termed, "fall-fever"), how do these changes and fluctuations contribute to male L. fulvus breeding opportunities, and potential reproductive success? These questions were investigated in the study of a semi-free-ranging ~ fulvus troop during the 1984 (Northern Hemisphere) breeding season. Utilizing an extensive ethogram it was found that, contrary to previous literature on the species, hierarchical social dominance relationships are indeed present in L. fulvus social groups. Additionally, it was found that these relationships play a crucial role in the reproductive behaviour of adult males. Statistically significant variation in the behaviour of the focal males is presented for seven inclusive behavioural categories. The picture of male L. fulvus reproductive behaviour that emerges from these considerations is then compared to the view derived from previous research on the species. Several amendments to our understanding of ~ fulvus social behaviour are suggested. An attempt is also made to place ~ fulvus in the socioecological categorizations of several authors.