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Vernal Pond Adventures

The largest of our vernal ponds in early April.

The largest of our vernal ponds in early April.

Once again I’m sitting beside our mountaintop vernal pond and wondering if this will be the year the wood frogs will make it out of the pond before the water disappears. A wood frog’s life span is about seven years, and for six years the pond has dried up before the wood frogs’ have fully developed. Some years their eggs are left high and dry; other years their tadpoles are.

A vernal pond is a temporary, fish-free wetland that fills in late winter or early spring and dries out by early summer in a good year. This pond is only several yards across and several yards long, depending on rainfall, and, unlike the tiny, 6-foot-wide pond at the base of First Field, I can’t get close enough to watch the courtship and mating of the frogs. I can hear their quacking calls, though, and I enjoy watching a wide variety of wild creatures that visit it even when I’m sitting quietly beside it, my back against an oak tree.

I find it incredibly peaceful to watch the pond as it reflects the trees in its still water. But this early March day a skim of ice over it glitters in the sunlight. Its surface has a medley of half circles and triangles artistically rendered by the ice-maker overnight.

On the thirteenth of March, as I near the vernal pond, circles appear in the water. I wonder if they can be disappearing wood frogs. I study the still, dark water and spot one small mass that I look at through my binoculars. A golden eye returns my gaze. I move closer and see a male wood frog stretched out in the water. Next to him is a stick with two clumps of wood frog eggs clinging to it. This unusually bold wood frog dives into the water but quickly resurfaces. Since I am still standing there, he sinks back under the water.

The vernal pond has already contracted, and I hope that the dark clouds rushing across the Allegheny Front will drop some rain on us and fill up the pond. But it doesn’t happen. Nevertheless, two days later, I find two wood frog egg masses in different areas. The gelatinous, fist-sized blobs contain several hundred eggs with black embryos.

By the 22nd of March, I count four separate egg masses, but the vernal pond is still shrinking. If the rain comes soon enough, the eggs may survive. And come it does, raining hard from 1:00 a.m. until mid-morning on March 24, filling up the vernal pond again.

The vernal pond in mid-March.

The vernal pond in mid-March.

It’s almost a month before I return to the pond. At the beginning of April, while hiking on Sapsucker Ridge with my sixteen-year-old granddaughter Eva, she steps on a branch and I trip over it, my left leg landing hard on a pointed rock. Nothing is broken or fractured the doctors tell me, but my leg and foot swell up and turn black and blue. I have, after all, injured my tibia, the bone just below my knee. After days of being veranda-bound and more days of slow, short walks, I finally make it back to a vernal pond seething with insect life, most notably water striders walking atop the water and looking for mosquitoes resting on the water just after they have emerged from their “wriggler” larval stage.

Various species of diving beetles also swim in the water on the hunt for invertebrate and vertebrate creatures, including the wood frog tadpoles. I have always marveled at how these insects find a vernal pond, especially this one, isolated on a mountaintop half a mile from the nearest stream and that one intermittent near its source. Apparently, they are able to fly to it from such water. But some species of diving beetles actually overwinter in the basin formed by a dried up vernal pond.

The wood frog eggs have long since disappeared from sight, colonized by the symbiotic algae Oophila amblystomatis, which turns them green. It’s been cold most of the month, delaying the hatching of the eggs. But near the pond I stop to admire the patch of spreading spring beauties, the only place they grow on our property. This is an open, mixed-oak forest close to our neighbor’s logging operation that took place several years ago. Not much has regenerated and the vernal pond is not as shaded as it used to be.

It’s now the fourth of May and torrid summer weather has returned. I practically stumble over a porcupine as I approach the vernal pond and send the creature scrambling up a large red oak tree. The vernal pond is a veritable tadpole soup—tadpoles by the dozens wherever I look, floating near the surface to warm themselves up now that the trees have leafed out and are shading the pond. They need the solar heat to develop quickly into frogs before the pond dries up. First they graze on the symbiotic algae still clinging to their gelatinous cradle, and then they feed on algae and leaf material on the pond’s bottom. They also may feed on each other, those that hatched first preying on the latecomers.

Three days of hard, cold rain follow, and once again the vernal pond is overflowing and seeping over into a series of wallow-sized pools. My pond-watching becomes an almost daily discipline as I sit and watch the tadpoles eating, swimming, and basking in patches of sunlight. In mid-May I hear clucking as a hen turkey circles behind me. Maybe she is hoping to catch some tadpoles for brunch.

water striders

Water striders

Often the tadpoles join in aggregations of ten on a submerged stick. Then there is a sudden flurry and they separate, but in a few seconds they gather together again, performing their own watery tadpole ballet. In addition to basking in the sun, perhaps they are finding refuge from predators in a crowd like flocks of birds do.

By the twentieth of May a few of the larger tadpoles are developing back legs. I sit close to the water and watch as the tadpoles continually surface to feed on the detritus floating on the water, then submerge, each tadpole swirling the water into a circle. I try counting the circles to figure out how many tadpoles still inhabit the pond, but the confusion of circles quickly confuses me. Instead, I settle back and enjoy the ambiance of the pond and surrounding woodland having long ago learned to tune out the occasional train whistle and the constant traffic noise on Interstate 99 at the base of the ridge.

A mourning dove sings without ceasing. Red-eyed vireos, eastern wood pewees and a scarlet tanager frequently add their songs to that of the doves. Water striders skate along the water. A common green darner dragonfly buzzes over the pond. Then an American crow flies in like a kamikaze fighter plane, veers when it sees me, and silently retreats.

There are more days of rain and again the pond overflows. The pond water is so dark that I can’t glimpse the tadpoles, but dozens of circles that gradually subside as I sit in front of the pond indicate their presence. Sitting beside the pond, a sudden nearby gunshot startles the tadpoles as much as it startles me. Not only do they have sharp eyes but sharp ears too.

Near the end of May, I’m serenaded by a robin and scolded by a hairy woodpecker while I sit beside the pond. I also see a dark-eyed junco, which should have been breeding farther north on the Allegheny Front or beyond by now. A mourning dove flies in to catch insects from the pond and goes off in a flurry when it realizes I am there. A black-and-white warbler sings. Chipmunks scold. Mosquitoes that probably have hatched in the pond circle me and force me to move on after I catch a glimpse of a few more tadpoles with back legs.

My vigil continues in June. By then, I wonder if those tadpoles will ever change into bandit-masked wood frogs. On June 8 many heads pop up from the water and stay up even though most tadpoles still have tails. Two male robins hold a song fest while a female chases all comers to the pond as her spotted youngster bathes. Later a tufted titmouse takes a bath. Chipmunks chase around the pond and one scampers up to me, pauses at my feet to look, and then continue its race with its rival. A pileated woodpecker pounds on a nearby tree trunk.

Wood frog in mating season

Wood frog in mating season (in the tiny, spring-fed pool at the bottom of First Field)

All the while a pleasant breeze blows, keeping biting insects away. The pond is slowly shrinking, but it is still a bathing and watering hole for birds and mammals alike.

The following day I spend another session at the vernal pond serenaded by the same two robins. Little mouths surface to catch detritus spread atop the pond, and once I see a tiny froglet hopping over a small section almost as if it could walk on water. Froglets are supposed to be between a half and 7/8th of an inch when they metamorphose. Their watery life is ending and none too soon.

A chipmunk approaches me with much trepidation, and when I don’t move, it goes to the pond and drinks. Then it scampers off.

Suddenly, the robins begin high octane scolding as if, after half an hour, they finally notice me. On and on they scold, but at last they subside.

When I am too stiff to sit any longer, I get up and walk back to the field path. There I find an enormous pile of fresh bear scat that wasn’t there before. It looks as if the robins were scolding a bear.

A couple days later, as I’m sitting by the pond, I hear crashing in the woods that sounds like a bear. Sure enough, one approaches the pond, and I ponder my position. It’s obviously hoping for a drink and doesn’t see or scent me. At last I stand up, and the bear looks up, sees me, and flees.

The vernal pond continues to fill every time it rains, and slowly the froglets depart, although I don’t see them. But there are fewer circles in the water, less little heads surfacing, every time I visit. How wonderful that after so many springs when the pond dried up too soon, our aging population of wood frogs will finally get some newcomers. The young frogs will spread out, traveling up to several hundred meters in all directions, making new homes in the leaf litter, and preying on a variety of arthropods.

But even as the pond shrinks and the froglets leave, I still seek quiet time beside it. One day, late in June, I encounter an eastern box turtle, floating in a couple inches of water, its eyes closed. At first I think it is dead, but when I touch it, it opens its eyes. Later, I learn that eastern box turtles like to soak and feed in vernal ponds.

Wood frog found under a rock in Plummer's Hollow Run in September

Wood frog found under a rock in Plummer’s Hollow Run in September

On another day, two doe wander past me and water at the pond while I sit a few feet away. Then they continue on their way. They never do detect my presence.

I can only wonder how many other wild lives are impacted by this small pond. Even though knowledgeable foresters will steer logging operations away from such places, most loggers either don’t know or don’t care about such refuges. Or they begin their logging operations in the fall when the ponds are dried up and they don’t recognize them for what they are.

My own life has been enriched by our vernal pond this water-full spring. Even after it is completely dried up, in broiling hot, droughty July, I wander back to sit under the oak shade. Where have all the wood frogs gone?

One day, on my daily walk, an adult wood frog hops across my path.

“There you are,” I say out loud as it hops quickly out of sight.

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