Why does taipei tree frog can be changed by temperature and and surroundings?

Pacific treefrogs like to live in damp places, wetlands, ponds, woodland, meadows and pastures. As long as these tree frogs have access to water, they can survive. Pacific treefrogs vary in color from bronze to lime green. They are the smallest and the most commonly seen and heard frogs. Pacific treefrogs are the only frogs with padded toes and dark markings. They can change their body color depending on their surroundings as well as the need to hide themselves. They also change color according to the seasons and temperature. At high temperatures, these frogs often turn a shade of yellow. Under cooler temperatures, they return to their more typical darker colors. Pacific treefrogs are social creatures, especially during mating season. Their call is quite distinctive, and they call in a chorus that can be quite loud. The call of these frogs is widely used in Hollywood movies as a night time background sound.

What's the yellow wallpaper?