Male and female developmental differences in chemosensory investigations by African elephants (Loxodonta africana) approaching waterholes

Although communication is vital for members of a social species, the sexes may differ in the type and degree of information sought. In many polygynous societies, males search for reproductively active females and compete intrasexually for access to females with older males often being most successful. In social mammals, females may mature sooner than males and thus at an earlier age behave more like adults. This maturation may include the assessment of potential mates directly or via indicative signals. In this study, we observed the behavior of African elephants (Loxodonta africana) during their approach to waterholes. Waterholes provide an opportunity for elephants to investigate conspecific chemical signals from feces and urine, and each other. We examined the presence of sexual dimorphism in behaviors of the trunk that are indicative of olfactory investigation. We predicted that upon approach to a waterhole, adult males would show greater interest than females in conspecific chemical signals. Females were predicted and observed to exhibit adult-like rates of investigatory behavior at a younger age than males because females mature sooner. Adult males took the longest to reach the waterhole in the last 100 m of approach; they also demonstrated greater investigatory rates to conspecific feces. Each sex showed adult-type investigative behaviors with the trunk before the age of reproduction. Rather than showing a common chronological developmental pattern across sex, the exhibition of investigatory, chemosensory behaviors reflected sex-specific changes in reproductive development, perhaps reflective of the relative strength of intra- and intersexual selection on communication patterns.