With another fresh blanket of snow on the ground after an especially cold and snowy winter, one of the first and noisiest signs of Spring has been delayed this year. However, a few days of warmer temperatures will be enough to bring out the wood frog and begin an amphibian breeding season that will last until summer.

Wood frogs are widely distributed in North America and notable for being found throughout Canada and Alaska. Indeed, they are the most wide-ranging frog in Alaska.

In Maryland, wood frogs usually emerge in late February and by March their loud choruses can be heard in full swing. With large numbers of wood frogs calling, their chorus sounds somewhat like a flock of hoarsely-croaking ducks. When combined with the loud high-pitched whistling of spring peepers—which usually emerge around the same time as wood frogs—a wetland in Spring can be a very loud place.

After spending the winter hibernating in leaf litter and forest duff, wood frogs are well-equipped to tolerate the fluctuating temperatures of their early breeding season. The blood of wood frogs works as a natural antifreeze, turning hard and crunchy as they freeze but preventing ice crystals from forming and damaging their cells. Where humans would get frostbite, wood frogs survive freezing and thawing due to the large amount of sugar in their blood—it protects them until temperatures are warm enough to remain active.

Along with many other amphibians, wood frogs require vernal pools and other temporary wetlands to lay their eggs. Vernal pools are a distinctive and important type of wetland that fill thanks to snowmelt and spring rains, but are often dry by mid-summer. They are a preferred choice for amphibians and other interesting animals because, as temporary wetlands, they do not support fish.

The eggs of wood frogs are laid in large clumps—a single egg mass can contain over 1,000 eggs! Many masses next to each other will form a large egg matt on the water’s surface. The eggs hatch in about 20 days and tadpoles transform into froglets after about two months, on their way before the vernal pond dries up.

The wetlands around Marshy Point are home to wood frogs and many other amphibians. Stop by the Nature Center to see some in our animal collection, or borrow an explorer pack before hiking Katie and Wil’s Trail to our wetland ponds.