Gray Treefrogs may be small, but they're incredibly loud. There are two species in the Upper Midwest, and they can only be told apart in the field by their voice. This one is a male Cope's Gray Treefrog, which has an raspy nasal trill. Its look-alike sister species is the Gray Treefrog, which has a sweeter more musical birdlike trill. Treefrogs often sing from low in the vegetation, as this one was. Adults such as this can change color, chameleon-like, over a day or so, to match their substrate. The frog's ground color can range from ashy-gray to bright green.