I talked with my buddy and award-winning naturalist Andy Larsen regarding the warbler migration, and he says the birds that were here in great numbers a few days ago have obviously moved on, and any that nest here have dispersed into their nesting territories and are not that obvious. He says they migrate on a barometric pressure high, and stop and rest whey they run into a low. When the low lifts thy all leave en mass, at night, and consequently just disappear from our sight. He will right a few paragraphs of more complete information which I will post at an appropriate juncture.
Lichens are another fascinating subject that we can explore at some point, but for now please note the photo of lichens on a red oak tree in the woods at about 12th and Manypenny avenue.