Cathleen Crosby recently photographed a Pacific Tree Frog, Pseudacris regilla, sitting on her spa. This frog can change colors to match their environment but they can't change to match a blue spa. Usually they are green but I've seen them turn brown and rusty-red. They eat insects, occasionally almost as big as they are. They have the ability to expand their body, something that would be helpful for humans at Thanksgiving!
This small frog is found on the west coast of the United States. Males are slightly smaller than the females and they have a black patch on their throats. This patch is actually their vocal sac. I can attest to the loudness of a male calling for a mate. Here Peter Baye photographed one in "full throat." Fun fact - this is the only frog who's call is "ribbitt."