Some of the Gray Treefrogs are the size of a penny when all hunkered down.

What sets the gray tree frog apart from some of our more commonly seen frogs in Ottawa are: they spend most of their time in trees and bushes, they can change colour from green to light gray and it is one of the smallest frogs I have seen in Ottawa. They're also nocturnal. I have to go there in the evening but only when the mosquitos are gone. I read that they tend to be more gray when the temps are cooler.