Mature male African (Loxodonta africana) and Asian (Elephas maximus) elephants exhibit periodic episodes of musth, a state in which serum androgens are elevated, food intake typically decreases, aggressiveness often increases, and breeding success is enhanced. Urine is a common source of chemical signals in a variety of mammals. Elephants in musth dribble urine almost continuously for lengthy periods, suggesting that the chemicals in their urine may reveal their physiological condition to conspecifics. We investigated the volatile urinary chemicals in captive male elephants using automated solid phase dynamic extraction (SPDE) and gas chromatography–mass spectrometry (GC-MS). We found higher levels of alkan-2-ones, alkan-2-ols, and some aromatic compounds in urine from males in musth than in urine from non-musth males or from females. Levels of ketones and alcohols increased as the urine aged, likely due to microbial metabolism of fatty acids. Protein-derived aromatic metabolites also increased in abundance after urination, likely due to microbial hydrolysis of hydrophilic conjugates. We suggest that microbes may play an important role in timed release of urinary semiochemicals during elephant musth.

Maned wolves (Chrysocyon brachyurus) are endemic to South America, monogamous, solitary, and threatened in the wild. Maned wolf urine has a pungent and powerful odour and is used for scent marking. There is evidence to suggest that the presence of a male may be required to initiate oestrus and/or ovulation, thus implying the presence of a primer pheromone. We have employed solid phase dynamic extraction (SPDE)/GC-MS to identify a number of volatile compounds in maned wolf urine. These include sulphur-containing hemiterpenoids which are predominantly responsible for the distinctive urinary odour, hemiterpenoid alcohols which are known bark beetle pheromones, and a variety of pyrazines, some of which are known to be insect pheromones. Hemiterpenoids are most likely biosynthesised via a shunt of the mevalonate pathway, while pyrazines are thought to be products of amino acid metabolism. The abundance of some of these compounds increases as the urine ages, perhaps providing a timed release of putative chemical signals.