Mallard duckling “wheezing”

[thesnowgoose]

Hello I have some mallard ducklings that are 3-4 weeks old and I have one that makes this wheezing noise when he breathes. I can hear him breathe and not the others. Also looks like he’s putting a bit more effort into breathing than the rest. He is probably half the size as his brothers and sisters. He eats and drinks. I checked his naval cavity and can see through it so not clogged. They have a pool to swim in so he can rinse his nostrils out whenever. Not sure what to do.

 

[Miss Lydia]

Are they swimming in cold water or warm? If not fully feathered they need to have warm water for swimming. Can you put up a video of the little on breathing? What are you feeding them are they still using a heat source? Forgot to say a video will have to go on YouTube or Vimeo or similar then copy and pasted here.