Michigan’s Winter Wonders: Green Frog

Winter weather has arrived in most parts of Michigan by now, bringing dread for some, and excitement for others. But have you ever wondered what’s happening under the snow? Many of Michigan’s reptiles and amphibians search for tunnels or other underground cavities to wait out the cold winter temperatures. Still others might remain underwater, remarkably surviving the long winter months with little to no oxygen!

Such is the case with the Green Frog (Lithobates clamitans), one of Michigan’s most abundant frog species. These semi-aquatic amphibians spend their winters hibernating at the bottom of permanent pools and rivers, “breathing” in oxygen through their skin, occasionally nestled among piles of leaf litter that give off some amount of heat as they decompose, and sometimes can be seen swimming before the water has frozen over, or through clear ice. *A common misconception of hibernating animals is that they spend the entire time ‘sleeping’, when in fact hibernation is rather a period of reduced activity.

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A green frog rests on a rock at MNA’s Joan Rodman Memorial Nature Sanctuary. Photo by Jodi Louth.

So, why spend the winter underwater rather than on land? Other frogs in Michigan like the wood frog, spring peeper, as well as toads, hibernate in tunnels and under leaf piles. These frogs are able to survive the freezing temperatures because they produce excess glucose which helps prevent freezing of the cells in their bodies, acting as a sort of antifreeze. Green frogs on the other hand, are not able to function in this way, and so they must stay in above-freezing temperatures through the winter.

Adequate winter habitat for these species is a critical part of ensuring their survival to the next season, and threats to that habitat exist – even as the snow flies! For many of us, fall is a time for “cleaning up”, for raking up all the leaves that have fallen (and jumping in the pile), then bagging them up and shipping them off to a community dump site. But this practice robs our yards and natural areas of needed habitat, not only for the insects that overwinter in leaf piles like caterpillars and firefly larvae, but also for the many reptiles and amphibians that call our state home. The leaves provide a “blanket” between the ground and the snow, they provide heat as they decompose in place which also returns essential nutrients to the soil.

There are so many benefits for Michigan nature from leaving the leaves, so skip the fall “cleanup” and enjoy reap the rewards come springtime. Learn more about Michigan’s many reptiles and amphibians, and their conservation needs, with Herpetological Resource & Management at herprman.com, and learn more about the benefits of leaving leaves, visit healthyyards.org or leaveleavesalone.org

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Lake Erie Waves, Great Lakes Forests, and Mudpuppies: this week in environmental news

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Turbulent waves in Lake Erie. Photo: Dave Sandford.

This Is What A Great Lake Looks Like After All The Vacationers Are Gone (Buzzfeed): Photographer Dave Sanford spent time on Lake Erie shooting the Great Lake’s turbulent fall season. From mid-October to mid-November, the longtime professional sports photographer traveled each week to Port Stanley, Ontario, on the edge of Lake Erie to spend hours taking photos. His goal was to capture the exact moment when lake waves driven by gusting winds collide with a rebound wave that’s created when the water hits a pier and collection of boulders on the shore. People are blown away that these are from a lake, and not an ocean due to the size and force.

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Crayfish in Burt Lake are thought to be on the decline. Image: Greg Schechter, Flickr.

Pharmaceutical pollution takes toll on crayfish and other species (Great Lakes Echo): Drugs seeping into groundwater threaten crayfish and have a domino effect of environmental impacts that harm fish and other species, according to new research. Pharmaceutical pollution happens when medicines are improperly disposed or flushed into septic tanks and sewers as the body eliminates them. Treatment can’t filter them so they make their way into lakes and streams. Crayfish are a keystone species, one that many others species depend upon. If they died, so would trout and bass. That would lead to algae overgrowth and in turn, insects and invertebrates would die when decaying algae used up all the oxygen. At this point there are not solutions for removing pharmaceuticals once they are in lakes and streams, so this is a prevention issue. We need to keep it out of the waterways, improving septic and sewer systems to filter pharmaceutical pollution is a critical need.

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Red pine forest in West Michigan. Image: Marie Orttenburger.

Researchers look to brace Great Lakes forests for climate change (Great Lakes Echo): Great Lakes forests will get warmer and suffer more frequent short-term droughts, scientists say. The stakes are high. Forests are staple ecosystems in the region. Many wildlife and plant species depend on forest stability. Plus, forests are a part of the regional culture. The approaches to climate change adaptation for trees are as diverse as the tree species.

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Underwater shot of a mudpuppy at Wolf Lake. Image: Alicia Beattie.

Secretive amphibian can provide pollution clues (Great Lakes Echo): The mudpuppy is a fully-aquatic salamander thought to be on the decline–though the extent of that decline is unknown. The foot-long amphibians are classified a “threatened species” in the state of Illinois and considered a concern throughout the Great Lakes region. Destruction and degradation of habitat, along with invasive species, are spelling doom for mudpuppies. Mudpuppies are also very sensitive to pollution. That characteristic could make them especially important to researchers. Population statistics and tissue samples could clue scientists in on the effects pollution and habitat degradation are having on those environments.

Fascinating Frozen Wood Frogs

By Stephanie Bradshaw, MNA Volunteer

Wood Frog. Photo: Jim Harding/Michigan DNR

Wood Frog. Photo: Jim Harding/Michigan DNR

As the cold winds and icy showers come over the land, many animals migrate and others find a warm spot to curl up with full stomachs for a long winter nap. For Michigan, temperatures can get so cold that we often joke that one would freeze solid just by stepping outside, and that is exactly what our friend the wood frog does to survive the winter.

How do they freeze themselves?

Wood frogs are able to live farther north than any other type of frog. How do they handle the freezing temperatures? As the temperatures cool, the frogs bury themselves in the mud. As the ground freezes, the water in their body pools into their center, around their vital organs, and they freeze solid. These frogs are as hard as stones or bricks of ice. The frogs exhibit no sign of life: they do not breathe, they do not even have a heartbeat. But, they are not dead. Scientists call this “suspended animation.”

Freezing can cause many severe damages such as dehydration, cell damage, and punctured blood vessels. To avoid damages, the wood frog floods its systems with a sugary, glucose substance that retains the cells’ water and prevents cells from freezing. So while the frog allows freezing to occur around the cells and organs, the glucose protects the cells from the damages of freezing.

How do they thaw themselves?

For reasons still unknown to scientists, wood frogs are able to thaw themselves in the spring. Even more amazing, they thaw from the inside out, their vital organs becoming active in perfect timing so that the frog can regain full life. This process of coming back to life takes one or two days.

After the frogs have warmed up, they are ready to begin their mating season. Since the ground thaws before the lakes and ponds, wood frogs are the first frogs to awaken in the spring. Mating earlier than other species gives them an advantage for their youth to grow and mature before summer begins.

Possible Applications for Humans

The blood sugar that the frogs use to secure their organs and cells is the same blood sugar as all other vertebrate animals, including humans. With more research into the secrets of the wood frog, scientists may discover ways of storing and reviving organs without damage to tissues, managing blood sugar for diabetics, and treating people after strokes and heart attacks where their blood ceased to flow.

Signs of Spring: Amphibians Return to Vernal Pools

By Annie Perry, MNA Intern

For many Michigan residents, there are a few tell-tale signs of spring: Springtime birds chirping after being gone for a long winter, green grass growing, flowers sprouting, and days getting longer. But MNA stewards have one more thing to tell them that spring is here: Salamanders and other amphibians migrating to vernal pools.

A salamander MNA steward Dave Richmond found in his yard in early April. Photo by Dave Richmond.

A salamander MNA steward Dave Richmond found in his yard in early April. Photo by Dave Richmond.

Each spring, amphibians make mass (well, mini) migrations to vernal pools and ponds, usually at night during or after the first warm rainstorm. Once at the vernal pools, these amphibians will mate and lay their eggs before returning to the forest. Dave Richmond, a steward at the Edna S. Newnan Nature Sanctuary in St. Clair County, spotted some of the first salamanders of the season early this month—which means spring must be here, after all.

Vernal pools are natural, temporary bodies of water that occur in a shallow depression. These pools typically fill during the spring or fall and may dry in the summer; have no viable populations of fish; and provide essential breeding and nursery habitat for several organisms, including amphibians. Many amphibian eggs have physical properties or toxic compounds that help deter predators, but amphibians that are dependent on vernal pools lack these protections. As a result, their eggs and young are vulnerable to both aquatic and terrestrial predators. Not all vernal pools dry up every year, but each pool has some feature that prevents fish from living there, such as low oxygen concentrations during the summer or shallow levels that allow the pool to freeze to the bottom during the winter.

The spring issue of Michigan Nature magazine includes a feature on vernal pools—keep an eye out to learn more about these unique and important habitats!