We have five musovy ducks that were born the same day and are now 7 weeks old. Two are much bigger than the other three, so I assume they are male. One of the small ones has thick legs and bigger knees, making me worry she is male, too. She's my favorite, though, but if she's male she's off the island. Please tell me she is female.

This one shows the three smaller ones. The one with the bigger knees is in the middle.

On the left is one of the bigger ones. To the right are the two girls with the (relatively) delicate legs.

Big knees with the spotted chest in the middle, to her right is one of the bigger ones that I think is a boy, behind her is one of the ones I think is a girl. So tell me, is this adorable spotted-chested duck male or female?
This one shows the three smaller ones. The one with the bigger knees is in the middle.
On the left is one of the bigger ones. To the right are the two girls with the (relatively) delicate legs.
Big knees with the spotted chest in the middle, to her right is one of the bigger ones that I think is a boy, behind her is one of the ones I think is a girl. So tell me, is this adorable spotted-chested duck male or female?