This little masked marvel was hopping joyfully in our woods on Monday, July 19. He’s a Wood Frog (Lithobates sylvaticus), one of the most studied amphibians due to its mysterious ability to survive severe cold. (Sex assumed from his being less than two inches long; females usually are slightly larger than two inches.)
As with other amphibians, the Wood Frog is an animal with a metabolic rate that is too low to produce the heat necessary to keep its organs working. That is, the Wood Frog’s operational body heat must be obtained from the environment; it is ectothermic or “cold-blooded.”
Even so, Wood Frogs are remarkably adapted to the cold for reasons not yet fully understood. They usually are the first amphibians to appear in early spring, even when there is still ice in the vernal pools and the northern limit of their range is thought to be the tree line of the Arctic tundra. (Brooklin, Maine) Click on image to enlarge it.