Hi,
As far as I know not all frog trees are capable of changing their colours (only some specific types of frog trees can). Here is some data (from Wikipedia).
One of the most interesting features of these frogs is their ability to change color from brown to green. Previously, it was thought that there where two different fixed colors that an adult tree frog could be. Now it has been found that some of them are actually able to change between the two. They can also change from lighter to darker. These color changing morphs are triggered not by color change in their environment, but a change in background brightness. This type of environmental change would be caused by seasonal fluctuation. A change in the dorsal coloration of a color morph takes anywhere from weeks to months to change, but has been shown to be a very useful cryptic survival feature for these frogs.
Best regards,
