I do same. Put stones into my bird bath. I don't raise bees,,, but neighbor 1/2 block away does. See his bees on my flowers all summer. There are also other bees that I see on my flowers. Mason bees, and some feral honey bees as well.I've put out shallow pans of water for them, with stones for them to stand on.
How do I know????
Neighbor knows his bees,,, and also knows the others that he seen, when we were chillin, and talking in summer near my flowers.