What is this substance?
I found this substance in my bird bath on June 28, 2018. It rained and filled the bird bath. Then it got hot and the water evaporated, leaving about 1 to 2 cups of a white puffy substance, the consistency of bread dough (pic attached). It dried into a crystalline substance (pic attached). Can you identify this substance?
My best guess is that this is mold or fungus that grew in your bird bath, that then dried out when the water dried up.
Here is a good link from the Audubon Society with information on how to keep your bird baths clean, and why clean bird baths are important for healthy birds:
Thank you. Is this a guess, or are you aware of a mold or fungus that has these properties?
A best guess. I checked with an ornithologist and she guessed the same thing, but neither of us are 100% sure.