The discovery of the 'transient' male Tibetan wild ass: alternative 'sneaky' mating tactics in a wild equid?

Male asses usually consist of two classes, social bachelors and solitary, territorial males. However, our observations of the Tibetan wild ass (Equus kiang) suggested a third class may exist. Unexpectedly, unidentified males were often found courting females within another male's territory. To test our hypothesis that a new social class existed, we compared 12 social behaviours among three putative groups. The third male-type spent less time herding and demonstrating flehmen, while spending more time retreating, trotting and in proximity of females, where they were more likely to engage in courtship and urine-marking. Based on increased time spent among females within other territories, the most courtship events, and minimal time invested in each courtship, they appear to employ 'sneaky' mating tactics. We discuss whether these 'transient' males are demonstrating an adaptive alternative mating strategy, or whether these behaviours result from a discrete developmental stage of bachelors unready to challenge a rival.