Ducks mites and lice

[Jaxall]

Do ducks get Mites or lice? I have 5 ducks and 2 geese and the ducks are just now fully feathered but my muscovy looks weird around her tail. Idk if it's just not grown in yet or a parasite problem maybe. Is this a problem usually with them?

 

[Miss Lydia]

Not usually unless kept in horrid conditions and without bathing water.
A picture would be good.