Across the EUP, the Frogs Are Singing...
Amphibian Calls Offer Critical Scientific Data
By Paul Gingras

The wood frog is being monitored by local volunteers for state and multi-national frog and toad surveys. The frog has the ability to freeze and survive, allowing it to live farther north than any other amphibian in the world.

To most, a misty, drizzly evening is a sign to stay home, but for frog and toad enthusiasts, it's prime time to seek area wetlands, where the trills, peeps, and ribbits of amphibians reflect the health of ecosystems in the Eastern Upper Peninsula. For both fun and science, people monitor the vast swamps and wetlands, some volunteering information for Canadian or American frog and toad surveys. They note the presence, or absence, of the area's hopping amphibians in a unique form of outdoor recreation that offers a chance for logical analysis, guaranteed natural awareness, and at times, even moments of serenity.

Three or four years ago, Cedarville resident Christine Perrault stood still on Beavertail Point, east of town, listening to the raucous peeps of spring peepers and the duck-like warble of wood frogs, two species now singing in the area. Above her were shooting stars, surrounding her were blinking fireflies, and before she left, a fox trotted past.

The northern spring peeper is the most abundant frog calling in the area. (Photographs courtesy of Bird Studies Canada)

"All of the nights are fun," she explained, part of the reason she has collected data for the past seven years, heading for the wetlands during the first weeks of May, June, and July.

Northern spring peepers are out now, she said, and although they are hard to see, they are easy to hear. Throughout the EUP, the males are filling the air with highpitched peeps, calling females to breeding areas ranging from cedar swamps to open wetlands that sway with cattails, where pickerel weed and arrowhead leaves float on the water's surface.

As adults, the tiny brown or tan tree frogs range from 0.75 to 1.38 inches long, and although glimpsing the wary ventriloquists can be a challenge, a patient observer may see an X, or part of an X, on the peeper's back.

Like many frog surveyors, Ms. Perrault visits the same stopping points, between Cedarville and DeTour, year after year. In some spots, she easily counts the number of peepers. In others, they are more numerous and their calls overlap, and some areas host a cacophony of voices too loud to differentiate, she said.

When she first learned about spring peepers, she thought, "It's the sound I always heard as a kid!"

The call of the northern spring peeper is one most likely to be recognized by area residents.

The wood frog is another common species calling from the EUP's forests and fens this spring. People sometimes confuse its voice with a bird, Ms. Perrault said. To some, it sounds like a duck quacking in the distance, while she describes it as a "subtle chuckle." Now floating on the surfaces of area wetlands, the wood frog appears gray, brown, reddish brown, or tan, with an unmistakable, dark mask over each eye.

Mike Vaal, also of Cedarville, said the wood frog is much easier to count than the spring peeper. It is well into its breeding season when the calls of peepers overcome its intermittent warble.

The wood frog emerges and begins calling for a mate even when ice remains on ponds and rivers, said James H. Harding, a frog expert from Michigan State University. In the EUP, the wood frog is well within its range-limit. No other amphibian in the world can live as far north as the wood frog. The tiny creatures can literally freeze during the winter, thaw, and sing again in the spring, Mr. Harding said.

Birds and flowers originally drew Mr. Vaal to EUP wetlands, where he found himself captivated by frog calls. Armed with plastic boots, mosquito repellent, and patience, he contributed to frog and toad surveys from 1999 to 2003.

Mr. Vaal said the calls of wood frogs and spring peepers are unusually abundant this year, which he finds encouraging. They began calling early, sometime around mid-April.

The calls of peepers and wood frogs will fade with the spring, Ms. Perrault said. Even now, they are being joined by the western chorus frog, a creature with a voice like a thumbnail drawn across the teeth of a comb. By June, most likely, this will be replaced by the voice of the green frog, which lives in almost any body of water, including ponds, rivers, and ditches. Its voice is like the plucking of a loose banjo string. Long after the spring breeding season ends and other species have gone silent, gray tree frogs will continue to call from the trees, some emitting slow, musical trills, others calling with lower, shorter, nasal-sounding voices.

While fun and serenity draw frog and toad surveyors back to the wetlands each year, the data they produce has a serious side. Frogs and toads are indicators of water quality, said Ms. Perrault, a groundwater technician for the Michigan Department of Agriculture.

"Frog species need a certain level of water quality to survive," she said. "If you don't have that level, the water becomes inhospitable, and you start losing species."

Throughout Michigan, many frog and toad populations are declining, said Kathy Jones, volunteer coordinator for the Marsh Monitoring Program of Bird Studies Canada, a project that focuses on wildlife and water quality in the Great Lakes Basin. Mrs. Jones coordinates survey volunteers, including the efforts of Ms. Perrault and Mr. Vaal. The program includes about 300 U.S and 300 Canadian volunteers.

In some areas, frog and toad population declines are normal fluctuations caused by varying annual conditions, such as drought or temperature, but some declines are caused by pollution or habitat destruction, Mrs. Jones said.

Regarding frog populations, the Straits of Mackinac area is on the only maritime shipping route that is not an area of concern in the Great Lakes Basin, she said. Information from frog and toad surveys in Mackinac and Chippewa counties is needed for comparison with problem areas. Surveys gleaned from healthy areas helps determine if others require environmental remediation.

Shipping routes that require remediation include the St. Marys River, which has been degraded by industrial pollution, the Detroit River, the St. Clair River, Lake St. Clair, and the Niagara River. Once an area of concern is noted, more intensive research is done, and Bird Studies Canada provides information to government and private groups that request it. The data is shared with scientific publications and journals, on its Web site, and the State of Lakes Ecosystem Conference.

The United States and Canada have been collaborating on water protection projects since the International Boundary Waters Treaty of 1909, Mrs. Jones said. From a 1987 reconfiguration of that treaty came the International Joint Commission, which deals with water issues affecting both countries. The commission focuses on all boundary waters, such the Great Lakes Basin and the St. Lawrence River.

Since 1995, the Marsh Monitoring Program has been used to gather data on frog populations and habitats to discover long-term trends.

Declines that have researchers concerned are the American toad, western chorus frog, green frog, and northern leopard frog. The American toad, which is declining by 3.8 percent each year in the Lake Huron basin, is of a greater concern than others because the species is a generalist, meaning it can survive in more habitats than other frogs and toads, which are restricted to wetlands.

As the American toad has declined in the area, however, the bullfrog is increasing by 3.3 percent each year, a fact that has surprised some surveyors.

In the Les Cheneaux area, pollution is not the main threat to frog and toad populations, Ms. Perrault said. Here, the threats are dropping lake levels, combined with building along the shore.

Ms. Perrault finds it encouraging that frogs and toads are not seriously threatened in the Straits area.

"We'd like to keep it that way," she said. "It is still pretty here, but things don't stay pristine if you don't pay attention to them."