When a “gray” tree frog isn’t gray

Fall is a time when our few amphibians are getting ready for a long winter’s sleep. But for a few weeks now, you might come across a frog or toad on your travels. If you are very lucky, you might even find the “chameleon” of the frog world: the eastern gray tree frog (Hyla versicolor). This frog has a misleading common name. I had assumed that being we call it the “gray” tree frog, it would always be gray. But this isn’t the case. It’s scientific name is more helpful. “Versicolor” means “color-changing” and that is exactly what this frog can do. Just like a chameleon, the gray tree frog can change its color from gray to brown to pale green to blend in with its background. This isn’t an immediate color change, but it happens fast enough to help keep these small frogs safe from predators. Especially with their camouflage colors, these small (1-2.5 inch long) frogs are easy to miss. Gray tree frogs also have white chins and bellies and yellowish legs.

You know it is a “tree frog” by the adhesive pad that it has on each toe. These pads plus a sticky mucus that acts like a kind of frog glue, allows tree frogs to climb grass, trees or even glass windows.

This frog is common across the American south, but also lives north to Manitoba, Canada. It seems to prefer habitats with mixed stands of shrubby trees like willows, pines and oaks and shallow water. They also like a lot of growth at the water’s edge. The last part of their common name fits them well. They may scale trees to a height of 30 feet.

During the day in summer, gray tree frogs rest in hollow trees or under tree bark or leaves. They come out at night to feed. Gray tree frogs are “opportunistic” feeders, eating whatever is available and fits in their mouths. They feed primarily on insects, spiders and other invertebrates.

Having bred and laid eggs in the spring and early summer and fed bugs for the past six months, “gray” tree frogs are now getting ready for hibernation. As the weather gets colder, they slow down and look for sheltered places to rest all winter. These frogs “hibernate” underground or under leaf litter, freezing solid. In the spring these “frogsicles” warm up and hop off in search of mating ponds.

So as you are out looking at fall colors on the trees, keep an eye open for these color-changing tree frogs as they get ready for a long winter’s rest.