Male African elephants, Loxodonta africana, can distinguish oestrous status via urinary signals KATHRYN R. BAGLEY * , THOMAS E. GOODWIN†, L. E. L. RASMUSSEN ‡ & BRUCE A. SCHULTE * *Department of Biology, Georgia Southern University yDepartment of Chemistry, Hendrix College zDepartment of Environmental BioMolecular Systems, Oregon Graduate Institute, Oregon Health and Sciences University (Received 19 June 2005; initial acceptance 9 September 2005; final acceptance 5 January 2006; published online 19 May 2006; MS. number: A10189R) African elephants are a polygynous species that raise offspring in a matriarchal society. Unlike females, males disperse, spend time in male groups and search for mates when mature. Urinary chemical signals aid males in detecting reproductively active females. A preovulatory pheromone has been identified in Asian elephants, Elephas maximus, but has not yet been experimentally identified in African elephants. In this study, the goal was to determine whether adult captive male African elephants can distinguish between urine from conspecific females in luteal and periovulatory oestrous stages as an indication that a preovulatory pheromone is released in the urine. Urine was collected from seven different female African elephants during their luteal and periovulatory periods of oestrus. Bioassays were conducted with nine adult male elephants housed at six different facilities. Males were presented with the two urine types and a control sample once a day over 3 days to reduce sample novelty, which can result in misleadingly high responses. All males showed greater chemosensory responses to the periovulatory urine by trial 3 with the ability to distinguish the urines increasing over the 3 days. This is the first experimental behav- ioural evidence that African elephants release an oestrous pheromone in the urine. The ability of the captive male elephants to discern between the two urine types bolsters the hypothesis that there is a preovulatory pheromone in African elephants and encourages efforts to identify it. Ó 2006 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. Chemical signalling provides a reliable, honest source of communication for sexually segregated species (Maynard Smith & Price 1973). Sexual readiness, physiological con- dition and individual identity can be conveyed through chemical signals, even in the absence of the sender, through the investigation of scent marks or excretory materials (Alberts 1992; Johnston 1999; Wyatt 2003). Through chemical signals, members of the opposite sex can locate one another while concurrently decreasing confrontations between same-sex individuals. For in- stance, in Asian elephants, Elephas maximus, one chemical signal from female urine attracts males to preovulatory females, while a different compound from male temporal gland secretion appears to repel subordinate males and females who are not in a preovulatory stage of oestrus (Rasmussen 1998, 2001; Rasmussen et al. 1996, 1997; Rasmussen & Greenwood 2003). Elephants are polygynous mammals that raise offspring in a matriarchal society. Males disperse, spend time in male groups, and search for mates when mature. An important aspect of reproductive behaviour for male elephants involves locating oestrous females. Urinary chemical signals play an important role in detecting reproductively active females. Chemical signal investiga- tion is performed by the dexterous trunk (Rasmussen & Munger 1996). Primary chemosensory behaviours include sniff, check, place and flehmen (Schulte & Rasmussen 1999). The flehmen trunk behaviour is directly related to Correspondence and present address: B. A. Schulte, Department of Biol- ogy, Georgia Southern University, Statesboro, GA 30460-8042, U.S.A. (email: bschulte@georgiasouthern.edu). K. R. Bagley is now at Center for Wildlife Education, Georgia Southern University, Statesboro, GA 30460-8058, U.S.A. T. E. Goodwin is at the Department of Chemistry, Hendrix College, Conway, AR 72032, U.S.A. L. E. L. Rasmussen is at the Department of Environmental BioMolecular Systems, Oregon Health and Sciences University, Beaverton, OR 97006, U.S.A. 1439 0003–3472/06/$30.00/0 Ó 2006 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. ANIMAL BEHAVIOUR, 2006, 71, 1439–1445 doi:10.1016/j.anbehav.2006.01.003