This treefrog lives up to the first part of its name, 'gray', unlike the one in the next photo which is green. These frogs can change their colour from gray to green, with various shades of both colours, depending on whether they are sitting on green leaves or on a tree trunk. The change doesn't happen instantly and can take some time. I'm guessing this frog was on a tree but decided to sit on the leaves for awhile. Presumably, in time, he'll be green, but right now he really stands out.