Latrine behaviour as a multimodal communicatory signal station in wild lemurs: the case of Hapalemur meridionalis

Abstract

Latrine behaviour is the repeated use of specific sites for defecation/urination, and is common among most mammals, including carnivores, herbivores, marsupials and rodents. While rare among primates, latrine use has been observed among some lemurs. It has been hypothesized that group-living primates may use latrines to maintain intergroup spacing (i.e. territorial defence) and for female advertisement of sexual condition. To test these, we conducted focal follows of three neighbouring southern bamboo lemur, Hapalemur meridionalis, groups in Mandena littoral forest of southeast Madagascar. From January to December 2013, we recorded all occurrences of latrine behaviour and characterized latrine sites to determine what factors influenced returning to specific latrines. Additionally, we attempted to elucidate the functional role of scent marking at latrines. We assessed the degree of home range overlap between neighbouring groups, and recorded intergroup aggression. Overall, latrines were almost exclusively visually conspicuous sites and located in the core areas of group home ranges. Best-fit models indicated that multiply visited latrines occurred more often in core areas, and were influenced by both sexes. Glandular scent marking at latrine sites was driven by males, and occurred more during the nonmating season. Males overmarked female scent-marks less often during the mating season and more often when younger males were likely to disperse. Thus, overmarking at latrine sites may function as a mate-guarding strategy to deter new males. Latrine use supports the energy frugality hypothesis, which proposes that lemur social systems, known for female social dominance and low rates of agonism, evolved as responses to the low productivity of Malagasy forests. The deposition of olfactory cues (i.e. faeces, urine, glandular secretions) at visually conspicuous sites may convey information to neighbouring conspecifics, thus reducing the need for intergroup agonism. Overall, latrine behaviour acts as a multimodal means of intergroup communication.