‘I think this is what is going on during the forced copulations; the female is non-receptive so she doesn’t wink and her vagina stays in this crazy convoluted state.’ When she is receptive, however, the female duck opens the lumen of the vagina so her mate can get further along her reproductive tract than unwanted males. She may not be able to choose whom she mates with but she can control the paternity of her eggs, which is, of course, the ultimate goal.
