The Superior Rivers Watershed Association is pleased to issue our sixth edition of Marengo Riffles.

Partner Spotlight: Go Marengo Fish Habitat Project

A cool partnership project with the Friends of Lincoln Community Forest, the Wisconsin DNR, Trout Unlimited, Landmark Conservancy, Superior Rivers Watershed Association and private landowners is returning large woods debris to the flood-ravaged Marengo River in the Lincoln Community Forest.  The Friends group will cut and anchor large trees at 4-6 locations within one half mile, so they extend into the river and create lost habitat.  DNR will do the cutting.  

Amphibians of the Marengo Watershed and Southern Lake Superior Basin

By Kevin Brewster. All photos by Dan Nedrelo.

Along with the first songs of robins and other migratory birds, one of the most characteristic sounds of spring are the breeding calls of frogs and toads. Male frogs and toads call to attract females to ponds, lakes, and wetlands for breeding. These songs and migrations to standing water are truly ancient rites, reaching back to a time when amphibians were the only vertebrate land animals. Around here, this usually starts by mid- to late April as water temperatures warm and amphibians emerge from winter’s hibernation at the bottoms of water bodies or underground. An often-unnoticed migration of salamanders from hibernation sites to woodland ponds takes place even earlier than the first frog calls, with salamanders sometimes crawling slowly across remnant patches of snow on their journeys to ponds. 

Wood frog

Spring peeper

Leopard frog

Boreal chorus frog

They rely on ephemeral (temporary snow melt and rain-fed) woodland or pothole ponds for breeding and egg laying.

Salamanders can travel over a mile from their hibernation spots to breeding ponds, retracing the same route generation after generation. One of the greatest threats to migrating amphibians is having to cross roads that have been built across their migration routes. In Europe and in some parts of the US, local people come out to rescue the animals from becoming road casualties by moving them across roads. The migration periods are usually intense and fairly brief, so human intervention can make a significant difference for a local population of salamanders or frogs. In some locations, special under-road crossings are constructed to guide amphibians across. Unfortunately, vast numbers of amphibians don’t enjoy this level of concern and fall victim to vehicles during annual migration. Key habitats like ephemeral ponds are threatened by logging, pollution, and a warming and drying climate. Because of the combined impact of these and other threats, amphibians have become one of the fastest disappearing vertebrate groups on earth. 

In northwest Wisconsin we have four species of salamanders: blue-spotted (Ambystoma laterale), yellow-spotted (Ambystoma maculatum), red-backed (Plethodon cinereus), and the mudpuppy (Necturus maculosus). The blue-spotted and yellow-spotted salamanders are among the species that require woodland habitat and depend on ephemeral ponds for reproduction. After breeding, they disburse into wooded areas, spending most of their time under damp leaf litter, decomposing logs, or in the forest organic soil layer hunting earthworms and other invertebrate prey. Back in the ponds, their eggs are in a race against time to hatch. The larval amphibians (tadpoles) must feed and grow, completing their metamorphosis into air-breathing animals before the ponds dry up with the approach of summer.

The other two salamander species-red-backed salamanders and mudpuppies-have more unique life histories. Red-backed salamanders belong to a group of salamanders known as lungless salamanders. They absorb oxygen directly through their skin, and have lost the need for an aquatic early life stage. They live in and under decomposing logs on the forest floor, not requiring migration to ponds to reproduce. Instead, their offspring undergo metamorphosis inside their eggs and hatch as fully-developed baby salamanders (known as direct development). Key habitat elements for this type of lifestyle include older-growth mixed deciduous or hemlock/cedar forests with moist organic soils and abundant decomposing logs and rocks for sheltering under and hunting prey. Mudpuppies belong to a group of amphibians that have retained their aquatic early-life body type (known as neoteny) and live in water all of the time, breathing through gills as tadpoles do. And just as fish require, their habitat water must be within a temperature and dissolved oxygen range that sustains them. They also prefer rocky stream bottoms that provide cover from predators and habitat for prey such as aquatic insects and other invertebrates.  

The frog calling periods described here are roughly specific to our northwestern Wisconsin springs. Most of the species listed here also occur further south and begin calling weeks earlier in some cases. As mentioned above, the early calling frog species, calling from April into mid-May, include wood frogs (Lithobates sylvaticus), spring peepers (Pseudacris crucifer), boreal chorus frogs (Pseudacris maculata), and northern leopard frogs (Lithobates pipiens). Mid-later calling species (early May through mid-July), include American toads (Anaxyrus americanus), gray treefrogs (Dryophytes versicolor) and Cope’s gray treefrogs (Dryophytes chrysoscelis).

American toad

Gray and Cope’s gray treefrogs

And finally, the later calling species (June through August or later) include green frogs (Lithobates clamitans), mink frogs (Lithobates septentrionalis), and bullfrogs (Lithobates catesbeianus). As they are found in and near permanent water bodies, these frogs are a familiar part of summertime experiences on wetlands, lakes, and river backwaters. 

Amphibians have important ecological roles to play, both as predators of insects and other invertebrates, and as prey to fish, wading birds, reptiles, and mammals. They are also important indicators of environmental quality because of their sensitivity to environmental change. They require consistent seasonal precipitation, moderate temperatures, relatively unpolluted water, moist soil environments, abundant prey, and diverse aquatic and terrestrial habitat. Their presence or absence can tell us much about the health of ecosystems that we all ultimately depend on.  

Green frog

Mink frog

Bullfrog

Do you want to contribute to our bi-annual Marengo Riffles Newsletter? Do you have a story, event, or information to share about the Marengo River Watershed? Email us at info @ superiorrivers.org to submit a piece for our Autumn or Spring edition!

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