Or is this Cope's Gray Treefrog, Hyla chrysoscelis? It seems the only means of distinguishing these two frogs in the field is their calls, and this one wouldn't sing for me. (An examination of the blood cells will work but I didn't have a microscope or a means of sampling its blood). This is still a youngster; I took a couple of photos of the frog sitting on my finger and hand give an idea of its size.
Here is the tree frog in its natural element. As its name suggests, the color of this frog is more commonly a patterened gray. The skin has cells called chromatophores, which contain granules of different colored pigments. Were this frog were to rest on bark the visual cues it perceives will trigger a series of complex changes, the end result being an alteration in the concentrations of the skin pigments, changing its color from green to gray.
