What are some unknown but mind-blowing facts about ducks?

It’s what’s called an evolutionary arms race. It’s when two or more species are constantly evolving due to selective pressure from the other side. It’s like how the Gazelle will slowly get faster due to being hunted by predators, and the predators slowly get faster so they don’t starve to death.

Ducks are in a similar predicament, but they’re in an evolutionary arms race with themselves. You see, male ducks will force themselves on female ducks that don’t want to mate, and it’s a problem for the ducks survival as a species.

Ducks will bond with each other when they mate, which will help the survival of the offspring. Ducks born to aggressive males or born to forced copulation don’t fare too well. This makes the females more selective with who they mate with.

To counter this, female ducks have evolved cork-screw vaginas with different passages so they can allow only the sperm of the duck they want to mate with to fertilise the egg.

On the other hand, due to the male ducks sexually aggressive nature they have evolved longer cork-screw penises. For ducks to successfully mate their cork-screw genitalia need to line up perfectly.