Drake loosing weight

[RebinNH]

I would try to catch him up or herd him to a pen all by himself. It sure sounds to me that he might have round worms. You could also check his gizzard to see if anything food wise is in there. If not he could have eaten something and it may be in his esophagus. If that's the case there's not much you can do but take him to the vet to get it removed. Ducks eat anything that doesn't eat them first just like chickens, but they're a little braver on eating non-food stuffs.
-is he active?
-is he able to sound off(quack)?
-have you been able to see his poop? If it's worms, you should be able to see them

Good luck.

My muscovy does not quack. He still hisses just fine. Hard to tell which is his poop, as I'm not out watching much, though where he sleeps the poop looks normal enough. I'll check more closely. None of them are particularly active with the slippery snow.

 

[RebinNH]

How old is her? If nothing else has changed I would recommend doing a fecal sample with your vet (there are also labs you buy kits from for at home testing). He might need wormed.

He was born last March. Do you have a link for the at home labs?

 

[Miss Lydia]

I looked for that book and can't find it.

I'm so sorry it's called "Storeys Guide to Raising Ducks by Dave Holderread. "Page 239 Parasites.
also on page 263 another reference to internal parasites.
If you have a vet you use take some poop in and let them do a fecal at least you could rule out parasites.
@RebinNH