The scientific name for the gray treefrog is Hyla versicolor it comes from the Latin name for “variable color”. Not only does the “gray” treefrog come in a variety of colors from gray to green to brown, it also has the ability to change color based on the time of day and the temperature. Remember it is an amphibian and cold-blooded or “ectothermic” – its temperature is based on the “outside” temperature. (Although my research has revealed different information on color change, that just makes me crazy! It points to the fact that you must compare your resources even if they are supposedly reported from reputable organizations everybody make mistakes and I guess I will just have to do some experiments on my own.) Most reports indicate that gray treefrogs get darker at night and lighter in color in warm sunny areas.
Gray treefrogs are “arboreal” – they live most of their lives in trees coming down only to breed. They live in forested areas near temporary or permanent bodies of water. (We had one living in the maple tree up by our barn. Since people have found them breeding in the water on their pool covers perhaps the one in our maple tree was going over to our neighbors pool to breed!)
Treefrogs have large, rounded toe pads which enables them to climb. Each toe produces a sticky, adhesive fluid that allows them to grip surfaces. Since they are nocturnal, at night you might find them stuck to your window waiting to catch a moth or other night flying insect. The adults also like to eat crickets, ants, flies, grasshoppers, beetles and even other frogs.
Adults have a blotchy pattern, that resembles lichens on a tree, on a gray to brown background that helps them to be “camouflaged”. They have a white spot, or rectangle, under each eye and a brilliant, yellow-orange splash of color beneath each back leg – a warning for predators not to attack! Their belly is white, the males throat is gray to black.
Although they make a variety of calls, the males are known for their breeding chorus that is a prolonged, musical trill. The males will select a “good perch” on a tree branch, over a pond that is not surrounded by leaves, for calling to females, beginning in late April, early May. They establish a “social distance” of 30 inches from other males during breeding season.
Females deposit groups of 10-40 eggs until 1,000 – 2,000 eggs are deposited. The tadpoles that hatch from the eggs are a bright lime-green and their colors change as they grow, when they get to about 2.5 inches they are an olive green with a brick red tail.
Like the wood frog and spring peeper the gray treefrog freezes in winter. It produces a glycerol that changes to glucose that acts like an “anti-freeze”. The glucose is circulated through the frogs cells. The rest of the water and blood freezes and the heart and breathing stops! They have been found to freeze, and survive, temperatures up to below 20oF. It appears that repeated freezing and thawing have little effect on the frog. Gray treefrogs can live 7-9 years in the wild if they are not eaten by skunks, opossums, raccoons or snakes.
I am going to keep checking our maple tree to see if I can spot a gray treefrog. Look around your yard, especially when it gets warmer, and let me know if you spot them…or if you hear them calling!
Stokes Guide to Amphibians and Reptiles by Thomas F. Tyning
Amphibians and Reptiles of Connecticut and Adjacent Regions by Michael W. Klemens