Glad to hear he's doing well. It should be about 90 degrees in the brooder, so if you don't think that light is doing that, you should look into buying a real one meant for ducklings. At this stage his mama would still be sitting on him, so he should be nice and warm.
I know it's hard but if you want your little guy to flourish you should make sure he has the right stuff :)
I wish you the best of luck, keep us posted! Those kittens are too cute. I'm so sorry about your other duckling :(
Okay, so I have absolutely ZERO experience with ducks, but I can't imagine they are completely different from baby chicks. If that person at the feed store won't sell your friend duckling starter, perhaps you can ask for no medicated chick starter, or simply not explain your situation. ( make...