Bitch: On the Female of the Species

by Lucy Cooke

When females are only receptive for a short period, a male can temporarily enforce her chastity by clogging her vagina with his coagulated seminal fluids. These plugs can get pretty big – in ring-tailed lemurs they’re over five cubic centimetres.2 They don’t make it impossible for subsequent males to mate, but they need to be dislodged so they are a significant obstacle. When the female is only receptive for a day or even less, this might make all the difference. A recent study by Amy Dunham, associate professor of ecology and evolutionary biology at Rice University, found that copulatory plugs are more common in species with short fertile windows (like the lemurs) and no difference in size between the sexes.