Sounds to my like your birds are flighted. Years ago, a friend of mine lost a Blue and Gold Macaw to a ceiling fan. Please use a tower fan when your birds are out of their cages.
In my humble opinion, ceiling fans and birds are a recipe for disaster!
I think that would work. Could be sort of complicated to position all the time, though.
Are you afraid your birds will fly into the fan? Why do you need that if the fan will be off, as I assume it would be.?