Photo of adelie penguins via sodahead
In 1998 Dr Fiona Hunter (Cambridge University, UK) and Dr Lloyd Davis (University of Otago, New Zealand) reported that they had observed female penguins trading sexual favours with single male penguins for stones (necessary for nest-building) on Ross Island. When penguins take a mate, they are usually monogamous. All the female penguins who exchanged sex for stones did it behind the backs of their male partners who apparently never caught their mates in flagrante delicto.
Stones for nest-building are in short supply on Ross Island. This scarcity may be one of the motivations for some of the small percentage of female penguins who go on the game. However, Dr Hunter believes that other factors may also be involved, especially since the female may only take a couple of stones in payment for her services even though hundreds may be required to build a nest. The females could be assessing the potential of single males in case their mate dies, for example. For the single male penguins, it is speculated that their only motivation is their own pleasure.
This is believed to be the first time prostitution has been recorded in the animal kingdom. Trading sex for food etc within a relationship between animals is however much more common.
(via theanimalkingdom:allcreatures:mabelmoments:knowledgerush)