Greetings from Kansas, frantic, and ! Happy you joined our community! Frankly, I have no idea. . I've never seen it but who knows? You should post in the Ducks Forum if you haven't and see what they have to say! Good luck! https://www.backyardchickens.com/f/42/ducks
Sorry, I have no experience with ducks, just chickens but the folks on the Forum redsoxs has given you a link to should be able to help.
I hope you enjoy being a BYC member. There are lots of friendly and very helpful folks here so not only is it overflowing with useful information it is also a great place to make friends and have some fun.
If you would like to share pictures and stories of your flock, you have come to the right place. BYC’ers never tire of these and do not back away slowly or commence eye rolling when the photo album or home videos come out