Scents and sensibility: information content of olfactory signals in the ringtailed lemur, Lemur catta ELIZABETH S. SCORDATO* & CHRISTINE M. DREA * † *Department of Biological Anthropology and Anatomy, Duke University yDepartment of Biology, Duke University (Received 17 March 2006; initial acceptance 16 June 2006; final acceptance 7 August 2006; published online 2 January 2007; MS. number: A10396) The function of olfactory signalling in social species is less well understood than in asocial species. Consequently, we examined olfactory communication in the ringtailed lemur, a socially complex primate that retains a functional vomeronasal organ, has well-developed scent glands and shows a suite of scent- marking behaviour. To assess the information content of different types of scent gland secretions, we decoupled olfactory cues from the visual and behavioural modalities with which scent marking is normally associated. We presented male and female subjects (signal receivers) with a series of choice tests between odours derived from conspecific donors (signal senders) varying by sex, age, social status and reproductive condition. We additionally examined the influence of the receivers’ reproductive state and familiarity with the signaller. The reproductive condition, social status and familiarity of senders and receivers affected signal transmission; specifically, male receivers attended most to the odours of conspecifics in breeding condition and to the odours of familiar, dominant animals. By contrast, females varied their responses according to both their own reproductive state and that of the sender. Based on male and female patterns of countermarking, we suggest that scent marking serves a function in intergroup spacing and intrasexual competition for both sexes, as might be expected in a female-dominant species. By contrast, minimal female interest in male odours counters a female mate choice function for scent marking in this species. Nevertheless, scent marks are critical to maleemale competition and, therefore, may be subject to sexual selection. Ó 2006 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. Keywords: chemical communication; female dominance; individual recognition; intrasexual competition; Lemur catta; mate choice; reproductive signalling; ringtailed lemur; scent marking; seasonality The study of mammalian olfactory communication fo- cuses on relatively asocial species (Ralls 1971; Brown & Macdonald 1985; Johnston 2003) that can benefit from the dispersed ‘bulletin board’ effect inherent to olfactory signals (Alberts 1992). In contrast, because social taxa rely on both visual and auditory means of communica- tion, researchers often treat visual and acoustic systems as the primary sensory modalities and substrates of sexual selection (Trivers 1972; Ryan et al. 1990; Andersson 1994). Although the function of olfactory communication in socially complex species remains poorly studied, odour cues are critical to mediating intragroup interaction, especially for those species that have specialized scent glands and display complex scent-marking repertoires. To better understand the function of chemical signals in such a species, we examined the responses of ringtailed le- murs to conspecific scent presented during a series of choice tests. Chemically complex mixtures of volatile and nonvolatile compounds (Belcher et al. 1990; Hurst et al. 1998), deposited as glandular secretions, urine, faeces or saliva, broadcast information in the absence of the signal sender (Mykytowycz 1970; Thiessen & Rice 1976). In relatively asocial species, this chemical matrix may contain infor- mation about sex, physiological and reproductive state (Swaisgood et al. 2000; Ferkin et al. 2004), territorial ownership (Hurst 1989; Brashares & Arcese 1999; Roberts & Dunbar 2000), and family membership (Buesching et al. 2002) or individual identity (Johnston & Jernigan Correspondence: C. M. Drea, Department of Biological Anthropology and Anatomy, 08 Biological Sciences Bldg, Box 90383, Duke Univer- sity, Durham, NC 27708-0383, U.S.A. (email: cdrea@duke.edu). 301 0003e 3472/07/$30.00/0 Ó 2006 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. ANIMAL BEHAVIOUR, 2007, 73, 301e314 doi:10.1016/j.anbehav.2006.08.006