What is this?

[HomesteadDucks]

I have 12 ducks and 2 geese. The ducks are soft and fluffy as always but the geese are not anymore. They appear to be losing the fluff on their backs and no feathers are replacing them. What is there is just crusty. Almost like sticky hair. Is this normal or is there something I could be doing to prevent this?

Edit: I might add that I have not seen any of them pecking at each other whatsoever.

 

[Messica]

It's hard to tell from the picture but could it be lice or mites? Did you get a really good look up close of the skin and the base of the shafts?