Chemosignalling of musth by individual wild African elephants (Loxodonta africana): implications for conservation and management.

Elephants have extraordinary olfactory receptive equipment, yet this sensory system has been only minimally investigated in wild elephants. We present an in-depth study of urinary chemical signals emitted by individual, behaviourally characterized, wild male African elephants, investigating whether these compounds were the same, accentuated, or diminished in comparison with captive individuals. Remarkably, most emitted chemicals were similar in captive and wild elephants with an exception traced to drought-induced dietary cyanates among wild males. We observed developmental changes predominated by the transition from acids and esters emitted by young males to alcohols and ketones released by older males. We determined that the ketones (2-butanone, acetone and 2-pentanone, and 2-nonanone) were considerably elevated during early musth, musth and late musth, respectively, suggesting that males communicate their condition via these compounds. The similarity to compounds released during musth by Asian male elephants that evoke conspecific bioresponses suggests the existence of species-free 'musth' signals. Our innovative techniques, which allow the recognition of precise sexual and musth states of individual elephants, can be helpful to managers of both wild and captive elephants. Such sampling may allow the more accurate categorization of the social and reproductive status of individual male elephants.