https://www.youtube.com/watch?v=gjN_nObFjDE
I was told and I believe that birds carry protozoans on their feet. So, when I saw a family of crows bathing in my friend's birdbath I thought I would find numbers of protozoans in the water when they left. Sampling the water, I did find bacterial growth but no protists. On the other hand, garden plants being rooted in a jar of water harbored masses of protists, amoebas and bacteria. An interesting comparison.