To investigate, the team recorded the behaviour of snow monkeys at Minoo, north of Osaka in Japan. With only adolescent female monkeys spotted mounting deer, the team compared the interactions to sexual interactions between adolescent female monkeys. The latter is a well known practice, and the only available comparison, as during the study adolescent females were not seen performing sexual mounts on adult male monkeys.

In total, the team recorded 12 successful interactions between monkeys, involving six adolescent females, between November 2012 and January 2013 – with a total of 67 mounts by the monkeys. In addition, 13 successful interactions of an apparently sexual nature were recorded between monkeys and deer between early November 2014 and January 2015, involving five adolescent females and a total of 258 mounts.