Wood frogs are found only in the United States and Canada. They are about three inches long and have bumpy skin that comes in several different colors, usually brown, tan, or rust, but sometimes green or gray. Their most recognizable feature is a black "robber's mask" that extends from the ear to the base of the front leg. Females are much larger than males. Wood frogs hibernate in winter, hiding under logs, stumps, or leaf litter. Their bodies freeze and their hearts stop beating. When spring comes, they thaw out and hop over to a breeding pond.
Wood frogs breed from early March to May in fish-free bodies of water, such as ponds, woodland pools, or water-filled ditches. To attract females, the male makes a call that sound like the quacking of a duck. He can’t identify females by sight or smell, so he must hug a potential mate and feel if it is large enough to be a female.
After breeding, the female lays a globular egg mass containing at least 1000 eggs in the water attached to a stick or plant stem. In about a week, the egg mass floats to the surface, and the gooey gel that surrounds it turns green, making it look like pond scum. The green color comes from algae. The eggs hatch after 9 to 30 days, depending on water temperature, and tadpoles undergo metamorphosis when they are about 2 months old. Male juveniles grow into adults when they are 1 to 2 years old; females do not become adults until they are 2 to 3 years old.
Adult wood frogs have many predators, including larger frogs, snakes, herons, raccoons, skunks, and minks. Eggs are eaten by leeches, eastern newts, and aquatic insects. Tadpoles are preyed upon by diving beetles, water bugs, and salamander larvae. Wood frogs have developed several anti-predator mechanisms. Adults have noxious skin secretions that repel certain predators. They also rely on their coloration to escape predators by blending into the forest floor. If captured, they emit piercing cries that may startle the attacker enough to release them.
We're pretty lucky to have wood frogs right in our back yard but it is purely by accident. Our yard is pretty dry with no vernal pools for them to lay eggs in but there is a pond rather close by for them. 2 years ago, we scattered an old firewood pile and tossed some soil on top and planted some ferns there. The result was a hill filled with air pockets which chipmunks, spiders and salamders have adopted as homes. This year we were lucky enough to find our first wood frog under the newly emerging ferns!