Runty duckling

[chocolate m'scovy]

I have some month-old Scovy ducklings. The problem is: one of them is drastically smaller than the rest. This batch had nearly 50% mortality from duck viral hepatitis; perhaps this poor litt'l fella is an asymptomatic carrier? Here he is next to one of his cotemporaries.

 

[chocolate m'scovy]

Oh, and in case you couldn't see from the photo, the runt still has his down, while his peers are growing in their wing and breast feathers. I've seen something like this before, on this forum; it was a post about chicks that just weren't maturing right and still felt like cotton balls?