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Many similarities exist between the lifestyles and behaviors of Loxodonta africana and Elephas maximus, two of the three extant species of elephants (Sukumar, 2003; Poole, 1987, 1989a,b; Rasmussen and Krishnamurthy, 2000; Rasmussen and Schulte, 1998). While the roles of olfaction and the chemical senses in Asian elephant society have been extensively investigated (Rasmussen and Greenwood, 2003; Rasmussen et a l , 1997, 2002), similar investigations in the African species are limited to recent studies of chemical signals among males (Rasmussen and Wittemyer, 2002). Male elephants face reproductive challenges not only of locating females, as the sexes live somewhat separated, but also of detecting the most fertile period of females, i.e. as they approach ovulation during the 13-17 week estrous cycle. The Asian species has been shown to utilize a urinary pheromone (Rasmussen et al., 1996). Commencing fairly early in the follicular phase, low concentrations of an acetate pheromone attract males (Rasmussen, 2001). The available urinary concentration of this ligand elevates gradually as ovulation approaches. Males apparently can measure quantitatively the pheromone concentration and thus the female's proximity to ovulation. This is evidenced by high frequencies of flehmen responses and premating behaviors. Based on selected field observations and unpublished data on captive elephants, our group recently began a rigorously designed multiple-elephants and multiple-sites study to establish whether male |
