14 July 2023
Water beetles were scuttling across Nebish Lake this morning. Each left a broad wake that parted a dusting of particles scattered sparse and even across the surface of the lake. I scooped a handful of water after we launched our kayaks. Each floating speck was a fragmentary insect exoskeleton or a birch nutlet. Under a hand lens, the scraps of insect resolved into heads, eyes, sheared-off-wings and legs, abdomens and thoraxes. Was this carnage, or the byproduct of molting, or both? Everything I looked at appeared to have come from a mayfly or mosquito. Leaves of the narrow-leaved bur-reed (Sparganium angustifolium) grew up from the bottom of the lake and arched backward to lie prone on the water’s surface. Pipewort (Eriocaulon aquaticum) stems extended from the lake bottom toward the surface, their tips glossy and swollen, like molten glass dropped in water and frozen on impact. Black-throated green warblers and red-eyed vireos sang from the shore. A belted kingfisher rattled overhead. Spatterdock rosettes spilled out extravagantly, visible in the clear water from tip to toe.
We paddled clockwise around the lake and came across a floating, sodden log. Each such log in these lakes is a Lilliputian garden. When we left home a couple of days ago, our yard was thick with flowering cup plants (Silphium perfoliatum) about 10 feet tall. The cup plants of this log were the sundews (Drosera rotundifolia), bristling with sticky hairs and all supporting flowering stalks just a few inches tall. Each inflorescence had eight to ten or more floral buds on it, each on the cusp of flowering. I hoped that they would all be open before we left for the week.[1] Growing with them were several other species typical of these floating gardens: Carex crawfordii, C. echinata, sweet flag (Acorus), bog St. John’s wort (Triadenum fraseri), northern bugleweed (Lycopus uniflorus), alder seedlings, mosses galore. We patrolled around to another log with a similar flora, this one also thick with sundews. Behind them, the lake was rimmed with tussock sedge (Carex stricta), leatherleaf, and swamp candles (Lysimachia terrestris) in full flower.
Rachel paddled ahead. I poked around the logs for a bit, then continued in the same direction, but I was soon waylaid by a chickadee along the shore. I happened to catch the bird emerging from a rotten red oak about ten inches in diameter and broken off ten feet above the ground. The chickadee flew into a white pine and looked around for insects, then pounded at the branch for about 20 seconds. Then it disappeared into the forest behind it. I paddled toward the nest while the bird was gone. A tangle of dead branches between myself and the oak distracted me from the tree where I had last seen the chickadee. When I turned back to the nest, I found the bird had flown back silently to the bough right above its tree. It was holding a caterpillar in its bill, looking a little disheveled. The chickadee stood for a moment glancing around. It seemed to know that something had changed. It darted into the excavation nonetheless, spent about 10 seconds inside, then flew off again.
I drifted closer. The chickadee returned after a few minutes with something small in its bill, perhaps a spider. It perched for three to five minutes this time. It scanned the forest around it, cocking or turning its head every second or two to get a composite picture. Then it flew to the edge of the cavity and jumped in abruptly, as you might jump into a pool when you are either used to the water or don’t want to think about how cold it might be. It remained inside for 40 seconds, then flew off again. I did not move. It returned shortly, entered the nest for ten seconds, then flew off. It called a soft “fee-bee.”
While the bird was out of view, I climbed onto land to get a closer look. The tree had broken off unevenly, leaving an oblique opening to the heartwood. The hole opened onto a vertical cylinder a couple of inches in diameter and about 10 inches deep. The excavation expanded at the bottom to accommodate the chicks. There were three or four of them that I could see, huddled at the bottom. It was deep enough that even with the light from my phone, I could see little more of the chicks than the lines radiating from the corners of their bills. They made no sound and did not move.
As I watched, the parent returned again, pissed off, loudly calling “chick-a-dee-dee-dee-dee.” Then the other parent—or at least some other chickadee—issued a loud chick-a-dee-dee-dee alarm call in response. I walked up slope to let the bird feed its young. The first bird moved to a perch right above the nest, looked around, and jumped in. I thought perhaps it would stay longer with its chicks this time, knowing I was around, but no: ten seconds and it was off again. The memory of a chickadee may be very short, or it may have deemed that I wasn’t a particular threat. In either case, the danger seems to have dissolved as quickly as it sprang up.
I made my way out while the birds were away. I worked my way toward Rachel through a bed of thick-stemmed spike-rush (Eleocharis palustris), passing a shoreline thick with Iris, sweet flag (Acorus), northern bugleweed, swamp candles, Carex crinita, C. stricta, C. echinata, C. stipata, C. comosa, C. hystricina, C. crawfordii. I passed a mossy hummock where two dragonfly nymphs had molted; later, I would find a mottled darner drying its wings and allowing its body to harden up post-molt in the same zone of vegetation, on the opposite side of the lake.
I met up with Rachel. Her kayak had inadvertently picked up a spider. Rachel had watched a loon pop up just eight feet from her boat, shake itself and dive again. We split an apple and a slice of swiss cheese skimmed from the fridge as we were leaving town yesterday and watched for the loon. Rachel saw it at a distance after a few minutes.
We headed to the opposite shore. I goofed around with a long-legged spider for a bit. I moved my hand close to it, and it stopped moving and stretched its legs to become sticklike. Then I tapped it lightly, and it raced like hell to another hiding spot. I did this several times, probably more than was necessary.[2] The spider dropped onto the deck of my kayak and worked its way to the front, where it set about stringing a web across the handle molded into the bow of the boat. My temporary spider and I kayaked past pileated woodpecker holes in a white pine, a red squirrel bounding along a log on shore, a fruiting Carex brunnescens, a song sparrow singing. We passed a floating log with C. canescens, C. hystricina with stubby little spikes, sundews, Triadenum.
Rachel and I returned to the boat dock and pulled our boats onto the car. We crossed the road and put in at Escanaba Lake. This lake is less than 300 meters from Nebish at its closest point, but the two feel very different. A colony of pickerelweed (Pontederia cordata) flowered along the edge of the cove where the boat launch. The cove was enjoying a plague of green frogs. Rachel picked up on it first. I couldn’t see them, and she advised me to just look for the eyes. Then it was obvious: hundreds of paired bumps in the water and mud beneath and around the pickerelweed, the eyes of scores of green frogs. The water churned with their babies, half-transformed tadpoles with tails and frogs’ bodies. The cove was lined with bur-reed and brimming with plants: flat-stemmed pondweed, Najas flexilis, a bed of common waterweed (Elodea canadensis) a bit closer to shore than the Najas, Potamogeton amplifolius a bit deeper, white water lily, spatterdock.Underwater, the leaves of Vallisneria with their broad midveins trailed up to the surfaces, everywhere but regrettably not in flower, along with the ladder-like Potamogeton robbinsii.
I was particularly struck by one of the sedges. While none of the floating log gardens we found in Nebish Lake hosted Carex leptalea, each of the three logs we looked at in Escanaba Lake did. To be fair, I could have missed the species at Nebish Lake. It might also be that with this small sample size, our estimates of the frequency of Carex leptalea on floating logs in Escanaba and Nebish—1.0 and 0.0 respectively—is inaccurate. Still, I wonder what these little gardens tell us about the lakes. Each log presumably is a filter for species migrating from, predominantly, the adjacent shoreline. Each shoreline lies in a different landscape position—a point that Susan Knight, who has more than four decades of experience on these lakes, would make in our conversation the next day—and consequently fosters a different flora, both in the water and, potentially, on land.[3] Each log is an island, assembling novel communities over and over from a local species pool.
We left the cove and traveled counter-clockwise around the main lake. Along the shore we found a rosette of tree roots standing roughly perpendicular to the ground. This was a red maple that stood, in life, perhaps 50 feet tall. Last year we found the fallen trunk canted backwards at about 30 degrees off vertical, frozen mid-crash. Its roots at the lower edge of the root ball were embedded in the bank, forming a fulcrum where they were still attached. At the distal edge, the roots had curled back away from the open water, leaving nothing to anchor the exposed side of the tree against storms. The forest here was dense, but almost certainly shallow: balsam fir, white pine, paper birch, Glyceria canadensis, bracken fern, shield fern, a thicket of beaked hazelnut, iris at the water’s edge. The mossy skin of the forest floor looked as though it were being peeled off, using the red maple trunk as a pull-tab.
The wind picked up. We prowled the edge of the open lake a bit, then turned around to return to the cove. We rounded a reef of bulrushes and paddled back along the edge of a spatterdock colony. We passed the same spot last year and found bubbles percolating to the surface of the lake, where they rested for a few moments before popping. That day, when the clouds passed in front of the sun, the temperature and light dropped, and it seemed to us that the bubbles stopped. I wondered at that time whether the bubbles might be leakage from air pumping through the spatterdock rhizomes.[4] But as the sun came back out, the bubbles did not start back up. Today, there were no bubbles. More observation is needed.
We drove back to the field station. That afternoon we wrote and painted, then we went out for a fish fry and, on the way home, put in at Lost Canoe Lake. It was a short paddle. Weather was threatening, and we ignored distant thunder when we put in. But after we’d puttered around for about 10 minutes next to the boat launch, the thunder wasn’t going away, and seemed like it might be coming closer. We dragged our boats up the hill to the car and headed back to Trout Lake. No storm materialized.
Featured image
Rice. Rachel Davis, 2022. Acrylic on wood panel, 16" x 20".
Endnotes
Returning to this a few weeks later, I realize that this was an unrealistic hope. The next week, at the annual joint meeting of the Botanical Society of America and American Society of Plant Taxonomists, I met with Dr. Rebekah Mohn of University of Minnesota, who studies sundews. I described the logs, and she told me that sundew flowers generally open for a very short amount of time, and the particular timing may depend on the species. When she finds a bud about to open in the greenhouse, she checks it every 15 minutes to half an hour as the flower may open and close within an hour. Kayaking at various hours over the course of five days, we didn’t find a single one open. ↩︎
It is seeming a lot likelier than I thought previously that insects may have consciousness. Spiders, too? Probably so. I certainly have no business messing with them like that. ↩︎
I have not seen any research on these tiny communities, though there is a study of the plant communities of floating logs and stumps in a South Carolina swamp. ↩︎
Spatterdock, water lily, and in fact most floating-leaved aquatics can pump air through their rhizomes. This pumping kicks in when high solar radiation pressurizes the gases in young leaves, forcing air down through their long petioles into the rhizomes and out through the older leaves (Dacey JWH. 1980. Internal Winds in Water Lilies: An Adaptation for Life in Anaerobic Sediments. Science 210: 1017–1019). I have read elsewhere—I cannot remember now where it was—that emergent-leaved species also engage in this kind of air-pumping. ↩︎
I am loving the return of A Botanist’s Field Notes, now with Rachel’s beautiful artwork.
Thanks for your kind words. And thanks, too, for your rusty-patch bumblebee email! I owe you a note!
I hope all is well.