Lethargic ducklings dying!

[SoggyForks]

One of my fawn and white runner ducklings is being super lethargic. I had another one acting this way the other day and she died - does anyone know what to do? She doesn't feel very warm so I brought her inside but I don't know what's happening!

 

[SoggyForks]

Update - she's a bit more lively but still very tired. Any advice would be helpful. I have her with some wet foot and water and a heating pad.

 

[SoggyForks]

Update: she died peacefully in my arms a couple of minutes ago.

 

[Wyorp Rock]

I'm sorry to hear about your Duckling.

I don't know anything about Ducks, do you have any others that are having issues? If so, @Miss Lydia or @Jenbirdee may be able to offer some care tips.

 

[Jenbirdee]

How many ducklings do you have? How old are they?
What have they been eating?
Do they live in an enclosure? What kind of substrate are they on? Do they also run around and free range?