Gray/grey tree frog

Without doing a sonal analysis and comparing at a known temperature, it is VERY difficult to distinguish these 2 species, particularly if the temp is below 16 C.

Hi floryj, this is either a Gray Tree Frog or a Cope's Gray Tree Frog, not a Green Tree Frog. Green Tree Frogs are not even found in Michigan. The Gray and Cope's Gray are visually indistinguishable and both are in your area so you can't tell at this point which species it is.