I've had this interesting thing happening this year at the pond. I thought maybe it was because we were so dry, but has continued after the rain. We have had these adorable bees drinking from the pond and stream edges. Yesterday I cleaned out some string algae and found that the bees were interested in sitting on the algae too. They seem to be sipping away as their little bums moved up and down. What's going on here? Is there some sort of attractive mineral or something in the water this year? I DO have more algae than ever before.
I suspect it's because the water there has filtered out the chemicals we put in our water. It's cleaner and more attractive to the bees. How neat to have that going on in your yard and great pics, too. Your bees ahave found an excellent source and will be coming for years.