Slowly we inched along the edge of the pond, which lies along the east side of Four Mile Road just south of Potter Road.
Bob Carstens held his hand up in the fading light signaling that we stop and listen. It was after 10 p.m., and the night was filled with an incredible amphibian chorus.
There were high flute-like trills from eastern gray tree frogs and American toads, a few low percussion-like "brrrrrrt-brrrts" from the green frogs, and all were keeping time with the swirling, wall-to-wall sound of the spring peepers; a little frog with a big voice. Phil Specter would have been proud.
To my untrained ear it sounded at first like a mish-mash of sound, all butting together and erupting in one loud continuous explosion. To Carstens' trained ear he could pick out the different amphibian sounds and after pointing them out to me I could kind of distinguish them. I couldn't begin to tell you how many frogs and toads were making the sound, but he could at least tell if it was similar in volume to past years; which was the purpose of our early evening visit to the pond.
Carstens, a retired educator and a well known amateur birder in the Grand Traverse region, is one of several volunteers who participate in Michigan's annual frog and toad survey, which is done in spring and early summer.
"This is our 13th year doing the annual survey," said Lori Sargent, the DNR's survey coordinator, "which has helped us collect a lot of valuable data to evaluate the state's frog and toad populations. It's way too early to tell much about long term trends, but this is a good start."
Declining populations of frogs, toads and other amphibians have been documented worldwide since the 1980s. Studies suggest amphibians are disappearing due to habitat loss, pollution, disease, and other issues.
"The frogs and the toads are at the forefront of our environment," explained the DNR wildlife biologist. "They are kind of like our 'canary in the mine,' which they used to use to make sure the air was breathable. If the canary didn't survive it was time to get out of there."
Michigan is at the forefront of Great Lakes states doing such surveys. Only Wisconsin has been doing it longer by a few years.
"There are more than 400 routes statewide, running through every Michigan county. We add routes every year, and the continued success of the program is dependent on volunteer support, like Bob Carstens, who has been with us since the start," added Sargent.
The surveys are conducted along a statewide system of permanent survey routes, each consisting of 10 wetland sites. The same sites are visited three times during spring and early summer. Observers listen for calling frogs and toads at each site, identify species present and make an estimate of abundance.
"When I first heard about the survey I volunteered right away to do it for Grand Traverse County," said Carstens, who has been birding for about 30 years. "I already had routes around the area for birding surveys, and this seemed a natural fit. I knew of 10 good wetland areas and ponds on the south side of the county along the Boardman River corridor and a couple of meadow-like ponds. My route covers about 12 miles."
Over the previous 12 years there hasn't been a lot of change in the frog and toad populations that he's observed, which goes along with the overall state trend, according to Sargent.
The biggest problem that's been observed so far is fluctuating water levels, according to both Carstens and Sargent.
"My counts are good this season and may be up slightly over last year, which was a very dry year," said the retired educator. "If there isn't sufficient water levels they aren't around, but they seem to come back strong when water levels are up again.
"This spring I've also heard chorus frogs and wood frogs as well. The eastern gray tree frogs were about as loud as I've ever heard them tonight. They were in excellent chorus," he added.
Those participating in the survey were trained by listening to tapes of the various frog and toad calls. After doing it for a few seasons, according to Carstens, you become pretty proficient identifying the various calls even though some are similar.
The most abundant species in our region are the spring peepers, green frogs, gray tree frogs, American toads, west chorus frogs and some wood frogs. You might also see or hear an occasional northern leopard frog and bullfrog. It's hard to miss that big bass "gunnnnk" of the bullfrog.
Take a walk some night just after dark along a wetland or a pond, stop and just listen. It's an incredible sound of almost musical-like notes, and when you listen intently the different sounds are very detectable. They do sound like a chorus. It's a soothing sound.
The annual survey is supported in part by the Nongame Fish and Wildlife Fund and proceeds from the sale of the vehicular Wildlife Conservation Loon plate.
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