This model of the female reproductive tract of the mallard is already 8 years old. I made it for a post long gone. It’s still not a bad model. The simple application was one of the first I made. For this post, I changed the animation to “true” and adjusted the background color to fit better in this post, but otherwise, it’s the same application as 8 years ago. The text is 8 years old too, with some minor corrections.
Male ducks are notorious for attempting “forced copulation” with females. So females have evolved vaginas that make it hard for a male duck to actually inseminate them, if they don’t want it to, by forcing it towards the dead ends.
Most times when male ducks force themselves on females, it doesn’t result in fertilization. Only 3% of duck inseminations come from forced copulation.
When a female does want to mate with a male, she will contract and relax internal muscles that scientists think help make sex easier.
The application on the right shows the female reproduction tract from the cloaca to the ovary. In most birds, only the left ovary and oviduct persist. This is also the case with mallards.