TIL that female Adélie penguins trade stones for sex during a shortage of stones. Extra-pair copulation often occurs at the male's nesting site, after which the female takes one or more stones. In contrast, when it occurs at the female's nesting site, the male doesn’t take a stone.

https://en.wikipedia.org/wiki/Prostitution_among_animals
#til #todayilearned
https://www.reddit.com/r/todayilearned/comments/1gnrgup/til_that_female_adélie_penguins_trade_stones_for/