Poultry and Ashes

So I've had a bucket about half of off wood ash that I shoveled up after a burn pile last spring which within weeks had filled with rain water. I've noticed my ducks and geese hitting this up on the regular in addition to the clean water which is abundant. I figure they know what's best for them so I've never stopped them. Plus I imagine it as a way to slowly and gradually amend my soils with some micro nutrients.

But I'm curious, anyone know what's up with this?

Good source of potassium. Birds, not having fingers to peel bananas with, have to make do with less tasty things than us apes.