GATEWAY TO NATURE: Spring Frog Chorus

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

Spring 2022 has been very cold and slow to arrive. The native liverflowers on my upland hardwoods sometimes start blooming on April 1st, but none were seen mid-month, and no wild leeks were coming out of the ground either. I still had piles of snow on the south side of my shaded driveway on April 16th.

The wetlands had ice in low areas, but a few places had open water. I keep daily weather records and counted 9.29 inches of rain and sleet from March 1 to April 15 of this year. April 2018 gave my land 34 inches of snow in the first half of the month, and I didn’t hear the chorus of “bells” of spring peepers until early May.

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

spring combs are loudest in shallow wetlands when temperatures warm and breeding begins. The marshy area just east of Kangaroo Lake is a great place to listen to the sounds of sleigh bells from masses of them at dusk in early May.

They are found throughout the Great Lakes region and overwinter under leaf litter, in logs, or hidden in other dense organic matter. They freeze during hibernation, but the glycerol in their body turns into glucose and acts as antifreeze. Then the ice inside their bodies melts as the spring thaw opens up the shallow wetlands where they breed.

The species name is cruciferous (KRU-si-fer) and refers to the brown X on their back. Their slightly enlarged toes allow them to climb upright reeds and other wetland plants, where the male sings his courtship call, ogling about once per second. They are among the first to start breeding in the spring. Their average size is about one inch.

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

In early spring, they congregate in ponds that might still have ice around the edges. This is where they mate when the male produces calls like the sound of a duck quacking. We often saw them in a few of the swales at The Ridges Sanctuary, alerted to their presence by loud “croaking” cries. Once the reproduction is over, the adults leave the water and do not return until the following spring.

Wood frog eggs are laid in gelatinous masses which may be attached to submerged vegetation and may number 3,000 per female. This species is one of the first to reproduce, and in a very short period of only one to two weeks. Tadpoles hatch in four or more days, depending on water temperature. The transformation from tadpole to adult frog takes from 45 days to three months.

leopard frog populations nosedived in the 1970s, but we have seen good numbers in several Lake Michigan shoreline habitats. Scientists have noted that these frogs do not live as long as they once did and lay fewer eggs than in the past. Environmental degradation may be the cause, as 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 are found near houses and gardens and can change color to blend in with their surroundings. My late husband, Roy, photographed one perched on our garden fence that sat there patiently, unafraid of our activity. It was a perfect heather gray to match the weathered wood.

This frog world chameleon can be gray, green or brown and prefers to live in large woods and forests. Its almost birdlike call may fool many people into wondering what makes this chirp.

The joy of finding these wood frogs on hikes is always an unexpected treat. We must preserve wetlands and marshes for these amphibians to continue their reproductive cycles so that the chorus of spring can continue to delight future generations.