DOOR TO NATURE: Spring Frog Chorus

A wood frog shows its black mask as it rests in a bed of moss. Photo by Charlotte Lukes

The spring of 2022 was very cold and slow to arrive. Native hepatica flowers in my upland hardwoods sometimes begin to bloom by April 1, but none were seen by mid-month, and no wild leeks were poking out of the ground either. I still had piles of snow on the south side of my shaded driveway on April 16.

Wetlands contained ice in the low areas, but a few spots did have some open water. I keep daily weather records and tallied 9.29 inches of rain and melted snow from March 1 to April 15 this year. April 2018 gave my land 34 inches of snow during the first half of the month, and I did not hear the “jingle bells” chorus of spring peepers until early May.

Four of the more common frog species seen in Door County are the spring peeper, wood frog, leopard frog and gray tree frog. 

Spring peepers are the most vocal in shallow wetlands as temperatures warm up and breeding begins. The marshy area just east of Kangaroo Lake is a great spot to listen for the sleigh-bell-like sounds of masses of them at dusk in early May. 

They are found throughout the Great Lakes region and spend the winter under leaf litter, in logs or hidden in other dense organic matter. They freeze during hibernation, but the glycerol in their bodies converts to glucose and acts as an antifreeze. Then the ice within their bodies melts as the spring thaw opens the shallow wetlands where they breed.

The species name is crucifer (KRU-si-fer) and refers to the brown X on their backs. Their slightly enlarged toe pads allow them to climb vertical reeds and other wetland plants, where the male sings his courtship call, peeping about once per second. They are among the earliest to begin breeding in the spring. Their average size is about one inch.

Wood frogs are fairly common and can be found in forests that may be quite a distance from any wetland. They range in size from one and a half to two and a half inches in length and are known by the distinct black mask across the side of their face. Their backs can be light tan to very dark brown. Wood frogs range across North America from coast to coast and are the northernmost breeders of all American amphibians.

Early in the spring, they congregate in ponds that might still have ice at the edges. This is where they mate as the male produces calls like the sound of a quacking duck. We would often see them in a few of the swales in The Ridges Sanctuary, alerted to their presence by the loud “croaking” calls. After breeding is complete, the adults leave the water and do not return until the following spring.

Wood frog eggs are laid in gelatinous masses that can be attached to submerged vegetation and may number up to 3,000 from one female. This species is one of the earliest to breed, and in a very short span of just one to two weeks. Tadpoles hatch in four days or longer, depending on the water temperature. The transformation from tadpole to adult frog takes from 45 days to three months.

Leopard frog populations took a nosedive back in the 1970s, but we have seen fair numbers in several Lake Michigan shoreline habitats. Scientists have noted that these frogs don’t live as long as they once did and are laying fewer eggs than in the past. Environmental degradation may be the cause because the loss of wetlands can be detrimental to many of these amphibians. Most frogs breed in vernal ponds or smaller wetlands where fish are not present.

One of the most interesting of the group is the gray tree frog, which can be found near homes and gardens and can change its body color to blend in with its surroundings. My late husband, Roy, photographed one perched on our garden fence that sat there patiently, with no fear of our activity. It was a perfect mottled gray to match the weathered wood.

This chameleon of the frog world can be gray, green or brown and prefers to live in large woodlands and forests. Its almost birdlike call can fool many people who wonder what’s making that chirping sound.

The joy of finding these woodland frogs during hikes is always an unexpected treat. We need to preserve wetlands and marshes for these amphibians to continue their breeding cycles so the spring chorus can continue to thrill future generations.