This story about taking a population census of Northern Michigan frogs ran in the April 2002 edition of Traverse, Northern Michigan’s Magazine.
It begins at sundown. A pip here…a peep there. Come dark, the band really kicks it, an ungodly cacophony of frog talk that pings off the trees in a deafening, metallic din. Let me tell you what it sounds like up close. I mean standing dead center in the middle of singing ground. I’ll save you the trip. Keep you from going out there and muddying a perfectly good pair of shoes.
It sounds like this: silent. I’m talking nothing. Nada. Not a peep. Not a trill. Wander into a meadow that seconds before threatened to split your skull with the piping of a gazillion frogs, and it suddenly falls quiet enough to hear your temper ringing in your ears. You’re upset, sure, because the only reason anybody would want to slog out to where the peepers do their thing is to see them in action. Trouble is, they not only clam up facing an audience, but hide out as well.
I realized the other day while standing knee-deep in a bog that although I’ve probably heard the calls of countless spring peepers in my life, I’ve never actually seen one. I don’t feel dopey for admitting this because I know I’m not alone.
We know they’re there because we hear them. Every frog and toad in Michigan (there are thirteen native species in all) has a call distinct from the rest. The boisterous little peepers are the most familiar, their April songs proclaiming winter over and heralding warmer days on the way. Be it a bog, swamp-pond, or puddle, up here it seems you’re never out of earshot of some froggy spot. And maybe that’s why frog talk is sometimes taken for granted, at times little more than just background noise for weekend spring flings and all-night deck parties.
But to biologists, frogs and toads (or “anurans”) are like fortune tellers for environmental changes. Think of them as slippery swamp-dwelling soothsayers. Acid rain and ozone depletion both revealed their negative effects on amphibians first—proverbial canaries in the environmental coal mine.
Understanding frogs and toads begins by counting them. That means an annual survey. The census-takers are Michigan DNR employees, volunteers, and amateur biologists like Mike Gill. For little more than a decade, folks like Gill have been helping keep a tally of highs and lows in frog and toad populations. With a masters degree in natural sciences and a down and dirty interest in amphibians, Gill helped organize local counters here in Northern Michigan years ago. With eight seasons under his belt, Mike Gill is the man when it comes to frog and toad know-how in these parts.
Fiftyish and sporting a beard that gives him a gnomelike appearance, Gill has happy blue eyes and good handshake. He wears Teva sandals and an oversized hemp sweater. Wayfarer sunglasses hang around his neck. There’s something of the hippie about Gill, and I like him right away.
We meet in a parking lot east of Traverse City: a hastily arranged meeting on “a not so good night for listening,” according to Gill. Two long-handled white nets, like those used for catching butterflies, protrude over the backseat inside his white Subaru. In the tape deck is a cassette of frog and toad calls. En route to the first pond we listen to the familiar chirp, chirp, chirp of the northern spring peeper. Fast forward to the trill of the chorus frog (a call that, according to James Harding’s guidebook Michigan Frogs, Toads, and Salamanders, can be imitated by “strumming the small teeth of a stiff pocket comb with your thumbnail”). And, finally, rewind to the clucking croaks of the wood frog. It’s early April, and according to Gill, these three species are the ones we’re likely to hear.
“Come early May, you’ll hear leopard frogs and American toads,” Gill says. “June, Fowlers toads and tree toads.” As we zip down twisting back roads, a pair of coffee cans with heavy wire handles (what I later learn are collection buckets) jostle on the floor of the backseat.
We’re only checking two ponds tonight. But Gill’s regular route includes 10 wetland listening sites and 45 miles of driving. Some ponds are close to the road. Some are deep in state land, way back on rutted two-tracks. A few are only accessible by foot, meaning two or three miles of hiking in the dark.
Like all counters’ routes, Gill’s is mapped and registered with the DNR. It’s “his” route: a handful of swamp ponds and bogs that Gill has come to know intimately over the years.
Counters are expected to log at least three runs annually during the spring, typically one per month from April to June. Setting out at dusk, flashlight and clipboard in hand, counters spend only three to five minutes per site, listening and jotting down numbers, before moving on to the next.
“The nights are long,” Gill says. “I usually finish up past midnight.”
When it comes to an accurate headcount, there’s this question of divining a number from the multitude of serenading frogs and toads. How on earth do you count them? It’s an inexact science. According to the DNR, counting is a “simple estimate of abundance for each species, using a simple call index based on values of 1, 2, or 3.” A calling rated a “1” is the random piping of individuals. A “3” is the kind of night-splitting banter where telling one singer from another is utterly impossible.
Such a survey is not as stringent as some of the counting that was required for Gill’s master thesis on frog and toad populations and habitat in eastern Grand Traverse County. There are three methods of counting frogs: sound, sight, and actual capture. Through his experience, Gill became a kind of frog stalker extraordinaire.
The Michigan DNR initiated the frog and toad survey in 1988. But it wasn’t until 1996 that a statewide system of permanent survey routes was started to monitor natural and unnatural population shifts and how these corresponded to environmental changes. Mike Gill and others have been out there listening to the frogs every spring, but unlike most folks, he understands what they are saying.
In Northern Michigan, the greatest problem facing amphibians has more to do with a simple loss of habitat rather than dirty water and ultraviolet radiation spilling through an invisible hole in the heavens. “History shows that we can do nasty things to the environment,” says Gill, “and amphibians will still survive. But no wild creature can live without the proper habitat. A tiny little toad can only hop so far.”
Frogs prefer the kind of small, mosquito-laden backwaters that are unappealing to most of us. Think murky silt ponds, river oxbows, marshes. One of the reasons frogs and toads avoid big water and seek out these backwater wetlands is to escape predation by large fish. Frogs and toads are remarkably sensitive to their habitats, thanks in part to their skin. Though they have lungs, they also have the capacity to “breathe” through their skin’s network of tiny blood vessels which absorb oxygen. In a similar manner, they can also “smell” the presence of fish in a body of water, and choose to hop on to better bogs.
Little by little, the swamps, ditches and boggy spots favored by frogs have been drained and filled. Over 50 percent of Michigan’s original wetland habitat has been lost—about 5.6 million acres of potential anuran habitat. Coupled with that is the troubling statistic that 75 percent of remaining wetlands are privately owned and more difficult to regulate. The problem is compounded when these less-than-appealing areas are situated near prime river and lake frontage, and thus more likely to be developed, altered, or at the very least, divided by roads, driveways and structures. As of 1998, Michigan had lost 70 percent of its original coastal wetlands.
Another concern besides habitat degradation is the fact that the Great Lakes are in a low-water stage, and have been for the past three years. The little wetlands, the woodsy puddles and ponds where frogs live and breed and sing are simply drying up. Such is the fate of the first pond Gill and I visit.
“You can leave your waders in the car,” Gill says gravely.
The “pond” is a bowl-shaped depression that’s dry as punk. Not a teaspoon of water anywhere. We walk along a fresh deer path, zigzagging our way through rotting timber. The trees, each as gray as a headstone, bear watermarks which show that a couple years ago, the spot where Gill and I finally pause to listen was once waist-deep silt and swamp water. Still, dry as it is, this remains one of Gill’s best listening ponds.
“Frogs and toads can burrow down in the mud and hibernate for years,” Gill says. “Temperature changes still trigger the breeding instinct, so they still come out at night to sing. Frogs and toads can live perhaps ten to twenty years, waiting for the returning water they need to reproduce.”
But we hear no peepers this evening. Not here. Gill declares it a little too early, and walking back toward the car begins doling out frog facts one after the other: Rainy and humid conditions bring out the most frogs and toads. Males do the calling. I follow along, imagining peepers asleep deep down underfoot, down where one can still wring a dropper of water from the earth.
It’s nearly dark by the time we part the yellow swamp grass and arrive at the next site. What biologist Gill declares a frog pond, my hunter’s eye sees as an ideal duck marsh: a hidden little sinkhole lined with cattails, swamp grasses and chalky-white aspen trees. The water is but ankle-deep, the pond bottom is the consistency of quicksand. Tiny puddles dot the landscape surrounding the lake. Big puddles and the kind of small, damp little depressions that tempt the child in me to go sloshing through. We hear peepers everywhere except near where we are standing, and then one strange trill over the din that I mistake as the song of a wood frog.
“No.” Gill shakes his head, wags a finger. “Peeper. Sometimes the peepers do that to fool ya.” Gill rates the calling level a solid “2.”
We stand there in the waning light, listening awhile. We’ve brought the white nets from the car and the rusty coffee-can buckets. Gill wants to show me a frog, wants to at least show me how to find them.
“Oh,” Gill says. “Looky there.” One adept dip of the net and I figure we have our first capture. But instead of a peeper, Gill palms the belly of the net, pulling back the folds to reveal a clear gelatinous blob.
“Eggs,” he declares, triumphant.
To me they look like caviar, or a hundred fish eyes suspended inside a quivering clear mass that I unabashedly proclaim looks like a tiny silicone breast implant. Gill points out others in the puddle before us: a half-dozen cloudy masses connected to submerged grasses or just free-floating under water.
“Could be from a salamander,” he says. “Or a wood frog. Can’t be sure without looking at them under the microscope.”
While Gill and I stand bent over, ogling the egg mass floating in his water-filled coffee can, the hubbub of frog sounds around us crescendo: peepers, some close by, calling frantically in the evening half-light. The calling reaches critical mass: Defcon 3.
I’m anxious to see just one of the little buggers. I always imagined the process of catching a peeper to be the same as how friends and I used to catch bullfrogs as kids. Once spooked from the bank, they could often be snagged in mid-leap with a net, just as a fan might snag a pop-fly down the first base line. And even if you missed, the frog would only stay down a moment or two before floating to the surface for a breath and a look around, upon which time you could promptly pocket him and draft him for service in grossing out your little sister later, a task which frogs always perform admirably.
But peepers don’t hide underwater; they hide near water, out in the grass. And you needn’t use a net to catch them. Gill gently pours the eggs back into the darkened pool with the others and then baby-steps his way into the grass. Not wanting to muck up his game, I stay a respectful distance behind, mirroring his heron-like hunting style. But our side of the pond is infuriatingly quiet. Our bumbling has inspired what seems an impromptu intermission from the nightly festivities. We creep along looking for a peeper to rustle the grass or, better yet, pipe up and betray its position. It’s a painstaking business, and with full dark coming, we give up hope for success.
Meanwhile across the pond, there’s another night sound: The buzzing peent of a male woodcock over the tumult of frogs. Gill hears it too and whispers how he so loves the night, how just last week he heard an owl, then a whippoorwill. Gill’s eyes dart over the grass, sometimes stopping to squint holes in the cover, and once he stops cold, foot frozen in mid-step like a dog gone on point. But it’s just a false alarm. For this night, the peepers hold on to that much of the mystery. I wonder if they see us stalking them, considering us with bulging eyes.
Bob Butz writes from Lake Ann. bbutz@traverse.net
For over 30 years the staff at Traverse Magazine has written about the history and natural world of our region. For the web series, Traverse Classics, we’ve reached into our archives to bring our favorites to our MyNorth.com audience.