Watching Cranes at Crex Meadows

“Turn here, they’re heading north!” I directed my fiancé as we navigated the gravel roads of Crex Meadows Wildlife Area near Grantsburg, WI. We’d spotted a line of sandhill cranes flying through the sunset sky, and were following them toward what we hoped would be a spectacular evening of birdwatching.

Thousands of sandhill cranes converge near this wetland complex each fall. They spend their days fueling up for migration by gleaning waste grain from recently harvested corn and soybean fields nearby. Then, at dusk they rise from the fields and stream into the wetlands. By roosting together in shallow water, the cranes make it harder for their numerous possible land predators, like coyotes, wolves, bobcats, and fishers to sneak up.

As we puttered along the grid of gravel roads trying to triangulate the most likely landing area for the flock, I felt like I was reliving my childhood of being on the chase crew for my grandpa’s hot air balloon in central Iowa. The difference was that Grandpa could communicate his plan to us through the radio in the old farm truck, and he was aiming for an accessible landing pad.

Balloons don't ALWAYS land in an accessible place...Photo by Larry Stone. 

These cranes had no concern for our viewing access. At the Crex Education and Visitors Center, we’d been warned that a recent influx of visitors had spooked the cranes away from some of their usual, easy-to-see roosts. Even when people are quiet, stay in their cars, and stay out of the wetlands, the birds may choose to go elsewhere. Luckily, this extensive wetland complex has plenty of space away from roads where the cranes could go to get some privacy.

That ability to hide makes it hard to keep track of their numbers. A few days after our visit, on October 29, the Wisconsin DNR conducted the annual survey of the crane population. Eleven staff spread out among known roost locations in Crex and the nearby Fish Lake Wildlife Area. Arriving before dawn, they prepared to witness the early morning commute of cranes from their bedrooms back to their breakfast fields.

Some cranes stay right in Crex Meadows and feed there throughout the day. This family to two adults and one juvenile crane were spotted earlier that afternoon. The second adult is feeding with their head down and is quite invisible in this photo. You can tell the adults by their red head, and the juvenile by the lack of it. 

“The total count with Crex and Fish Lake was 7,754 cranes,” reported DNR wildlife biologist Joe Dittrich when I called him up the day after the survey. In contrast, the average over the last three years was 13-14,000. That’s a sharp decline. Dittrich wasn’t too worried about the numbers, though. The morning of the count had been extremely foggy, especially at the Fish Lake unit, with visibility of only 100 yards. He suspects that they missed about half of the birds there. It’s also possible that some birds have already continued on south to their winter habitat in southern Georgia and Central Florida. No banding or telemetry efforts have established more specific migration routes or schedules for the birds who pass through here.

Even if some of the birds have left, Dittrich assured me that a good number of them will likely stick around until the wetlands begin to freeze up during the day. With the warm fall we’ve been having, that might mean we have several more weeks to witness this phenomenon. The Crex Visitor Center is happy to provide current information if you call 715-463-CREX.

“I really like their calls,” Dittrich told me when I asked what he liked best about the cranes. That’s no surprise. Many of us have heard one or two cranes give their thrilling, rattling, bugles during spring migration or nesting season. The cacophony of hundreds or thousands of these ancient voices echoing across the sunset is unforgettable.

Aldo Leopold wrote eloquently of the cranes in the “Marshland Elegy” chapter of A Sand County Almanac. “Our appreciation for the crane grows with the slow unraveling of earthly history…When we hear his call we hear no mere bird. We hear the trumpet in the orchestra of evolution. He is the symbol of our untamable past, of that incredible sweep of millennia…”

That isn’t mere hyperbole. Cranes are some of the oldest living birds. In Nebraska, a 15-million-year-old crane skeleton records their ancient stake on the territory. Over that time scale, the habitat has changed more than the bird. Several glaciers advanced and retreated. The last one here in Wisconsin sent a flood of sandy outwash southwest from the Bayfield Peninsula, creating the Northwest Sands Ecological Landscape. Then a rogue, northeast-flowing section of ice dammed up some of the meltwater, which created Glacial Lake Grantsburg. The lake’s calm water accumulated clay sediment. Together, the patchwork of sands and clays, along with science-based wildlife management, has turned this area into a destination for nature lovers of all kinds.

The Northwest Sands mostly failed at farming, and now host lots of important wildlife areas! Source

FIGURE 6. Advance of the Grantsburg Sublobe, an offshoot of the Des Moines Lobe, overriding the St. Croix Moraine blocking southward drainage of the Mississippi River, and forming glacial Lake Grantsburg.  Source

And yes, I was thinking about the glaciers as we stood at the edge of the wetland watching the flocks of cranes appear on the horizon, stream in over our heads, and descend with legs dangling into the water we knew was hiding behind grasses and shrubs. That old ice is the reason the cranes are here, and this winter’s ice is the reason they will leave. In between, their rattling cries send an awestruck shiver down my spine.

I took this video on October 14, when the cranes were still landing just north of Main Dike Road. Spectacular! Turn up your volume! 

 

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is available to purchase at www.cablemuseum.org/books and at your local independent bookstore, too. Natural Connections 3 is almost here!

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. Our Fall Calendar is open for registration! Visit our new exhibit, “Becoming the Northwoods: Akiing (A Special Place). Follow us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.

Fantastic Fungi

The air shimmered as I walked through the forest, the heavy mists encompassing me in a damp blanket. As my shoes trod on soggy leaves, I took in the quiet serenity of the forest. Many of the trees had begun their annual changing of the colors, painting the canopy in shades of yellow, orange, red and green. Their discarded leaves were already beginning to dot the forest floor in late September. But fallen leaves weren’t the only contributors of color on the ground–the fall mushrooms were popping in the Northwoods.

A bright splotch of red and orange drew my gaze downwards, where a species of waxy cap mushroom was growing among the green blanket of moss. They are characterized by being very colorful, with a shiny, waxy looking cap, and thick gills. And unlike many other mushroom species, they are not mycorrhizal or saprobic. This means they don’t obtain their nutrients through extensive networks of mycelium that form a symbiotic relationship with plant roots, or obtain nutrients from decaying wood and organic matter like saprobic mushrooms. Waxy cap mushrooms are biotrophic, forming a symbiotic relationship with the roots of grasses and forbs, as well as the rhizoids of mosses, obtaining nutrients from them.

A brightly colored waxy cap mushroom growing up from the forest floor. 

Many other mushroom species inhabited the forest, making it come alive with fungi. Saprobic fungi in particular were very prevalent. Resinous polypores clung to decomposing trees, making it seem like the trees were growing pancakes dotted with maple syrup from their bark. Tiny Marasmius mushrooms sprouted from the top of a mossy log, their spindly brown stems and grooved white caps made my imagination run with thoughts of them being used as umbrellas by small woodland invertebrates. And even while my imagination ran wild with these fun fungi appearances, I was appreciative of the ecological role they play within the forest. As saprobes, they were breaking down the wood they inhabited and recycling important nutrients back into the soil.

Resinous polypores on a decaying log. 

But the wealth of different mushrooms carried with it many different feeding styles and ecological relationships. One complex and interesting ecological relationship that can be found in the Northwoods is between Entoloma abortivum mushrooms and honey mushrooms in the Armillaria genus. These fungi can be found grouped together in forests, and though they have an inconspicuous appearance, they are waging war beneath the soil. One of these mushrooms is parasitizing the other, disrupting the development of the other’s fruiting body and prohibiting them from reproducing.

Honey mushrooms in the Armillaria genus, have a brilliantly nefarious adaptation in regard to how they obtain their nutrients. They are both saprobic and parasitic. They infect their host, sapping its nutrients and eventually contribute to its death. Typically, this is the end of a parasite's ability to get nutrients from its host. However, since honey mushrooms are also saprobic, they continue to derive nutrients from their now dead host tree by breaking down the wood, and decaying the tree. This capability is called necrotrophism.

The other half of this fungal relationship, the Entoloma abortivum, are light grey, plain looking mushrooms that are typically found near decaying wood. While this mushroom's dull appearance may seem like a barrier to identification, Entoloma abortivum can at times provide a hint to its identity in the form of a lumpy, mass of white fungal tissue near the Entoloma’s fruiting body. This odd looking fungal body was originally thought to be an “aborted” form of the Entoloma, caused by a parasitic attack on the Entoloma as it was beginning to fruit.

Because honey mushrooms are parasitic, and are often found fruiting in the vicinity of the Entolomas, they were originally thought to be the aggressor in the Entoloma vs honey mushroom war. However, in 2001 a scientific study by Czederpiltz, Volk and Burdsall found the opposite to be true. They found that the “aborted” Entoloma were actually deformed honey mushrooms that were attacked by Entoloma abortivum hyphae– showing that the Entoloma is the parasite, not the honey mushroom! Since the parasitic attack happens underneath the soil, and involves both mushrooms' complex network of mycelium, there are times where the fruiting body of the honey mushrooms are not found near the Entolomas. But, with the presence of the “abortive entoloma”, we know that the honey mushroom mycelium is underneath the soil, but was parasitized by the Entoloma before it could fully fruit.

Entoloma abortivum and the "abortive entoloma".

It is amazing to me that a simple walk through the forest to see fall mushrooms can reveal so many ecological connections taking place. From stepping on soil that hides a vast network of mycelium, stretching out through the soil to obtain nutrients– to passing by a decomposing tree littered with saprobic mushrooms, slowly breaking the tree down and returning it to the soil. One can always find something to marvel at in the Northwoods, especially in the fall.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. Our Fall Calendar is open for registration! Visit our new exhibit, “Becoming the Northwoods: Akiing (A Special Place). Follow us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.

Butterfly Breezes of Fall

A gentle breeze rippled the surface of Gabimichigami Lake. Paddling steadily in the bright sunshine of early afternoon, we were grateful that it wasn’t a steady wind. More than a mile of open water surrounded us with no islands or points to hide behind as we crossed from one portage to the next on our annual Boundary Waters canoe trip.

Hillsides of young aspen and birch glowed golden in the distance. At first, a flutter at the edge of my vision made me think that an autumn leaf had somehow managed to fall half a mile to the middle of the lake. A closer look revealed the dark purple wings of a mourning cloak butterfly. In late September?

I’ve often looked for mourning cloaks in early spring, knowing that these are one of a few butterflies who overwinter as adults and emerge as the snow is melting. They feed mostly on tree sap, fruit juices, and the honeydew excreted by aphids, so it’s not hard for them to find food even before most flowers bloom. They make the most of sunshine even on cold days by spreading their dark wings and body to absorb warmth.

A mourning cloak butterfly suns themselves on a paper birch tree. Photo by Emily Stone.

The adults mate and lay eggs even before the leaves of their larval host plants emerge. After the caterpillars hatch and feast on willow, aspen, birch, or a variety of other tree leaves for a couple of weeks, they form a pupa. After another couple of weeks, they emerge as adults in June or July. This seems perfectly timed to take advantage of peak flower availability, but abundant nectar doesn’t tempt them to feast. Instead, the new adults pause their development and go into a period of dormancy similar to hibernation, called estivation.

Then, in September and October they begin another active period, presumably to build energy stores before their winter round of hibernation. While mourning cloaks aren’t considered migratory, there’s some evidence that some individuals do migrate, perhaps to find a slightly warmer place to overwinter. Wherever they go, they’ll snuggle into hollow logs, wood piles, and loose bark. Hopefully, wherever they hibernate also gets blanketed by insulating snow and becomes part of the stable environment of the subnivean zone.

Throughout the trip, I saw at least half a dozen mourning cloaks out over the water, dancing in and out of the dappled sunlight at our campsite, and briefly landing to bask on sunny, warm rocks. Seeing them reminded me of an early spring hike up to St. Peter’s Dome, when I photographed a mourning cloak sunning themselves on a birch tree.

Mourning cloak butterflies become active in fall after a period of summer dormancy. This one photobombed a sunny afternoon on Saganaga Lake in northern Minnesota.

Photo by Emily Stone.

It’s not a bad schedule, really. Emerge into the gently warming days of spring. Take a siesta during the hottest days of July and August. Enjoy a fall feast before tucking in for the winter. They use this plan to survive across North America and even in Asia and Japan.

I even spotted one mourning cloak as recently as last week on the Superior Hiking Trail above Silver Bay, Minnesota. After watching their irregular flight until they disappeared in to the forest, a flutter at the edge of my vision caught my attention just in time to watch an autumn leaf come to rest on the ground.

Small quaking aspen leaves carpeted the trail in a mosaic of yellow and green. They were evidence of yet another way that a Lepidopteran (butterflies and moths) survives the winter. Green leaves don’t usually fall from the tree, but the trapezoids of chlorophyll captured between the first and second veins on one side of the leaves’ midribs told me all I needed to know. These were the larval home of a tiny moth.

A moth larva creates this green and gold pattern in quaking aspen leaves.

Photo by Emily Stone.

Back in July, a small, brown moth with white-fringed wings laid an egg on the leaf petiole. By September, a translucent larva hatched and bored into the leaf’s petiole, causing the stem to swell into a small gall. Munching her way up inside the leaf under the cover of darkness, the leaf-mining larva interrupted the mechanisms the tree normally uses to draw chlorophyll out of the leaf during the waning days of autumn.

Such a tiny caterpillar would dry out in the summer heat if she tried to pupate high in the tree canopy. Instead, she timed her life cycle to hitchhike on a falling leaf down to the damp forest floor. Now there, she is stealing a few more bites of the green energy she’d hoarded in the leaf. Presently she will pupate in relative safety and an agreeable microclimate. The soon-to-be-moth spends the winter in her cocoon, which is loosely woven to the surface of the now-brown leaf.

Colorful leaves and colorful wings flutter on fall breezes, all getting ready for winter.

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is available to purchase at www.cablemuseum.org/books and at your local independent bookstore, too. Natural Connections 3 will be published in November 2025!

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. Our Fall Calendar is open for registration! Visit our new exhibit, “Becoming the Northwoods: Akiing (A Special Place). Follow us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.

Flying Kittens

“Just hold her like this,” Kurt told me. So I carefully nestled my first two fingers into the soft, warm feathers around the neck of this tiny northern saw-whet owl, cradled her soft, warm torso in the palm of my hand, and secured her brown and white wings with my thumb and other fingers. My heart stopped for a moment, but under those soft, warm feathers I could feel her smaller heart racing.

Kurt opened the sliding door onto the deck of his cabin. I paused to snap a photo of her huge, yellow-ringed eyes staring back at me in the dim light. Then we walked out into the night. As we waited for all our eyes to adjust, I focused on the feel of this incredible being in my hand. So soft, so warm.

Mike Avara, another scientist who is recruiting volunteers for some exciting new owl research in Bayfield County, affectionally described saw-whet owls as flying kittens. Indeed, the feel of her took me back to childhood when my cousin Meggan let me, a member of a family with no pets, hold one of the several very new offspring of her barn cat. Even as a child, the experience provoked an intense sense of responsibility along with the joy of connection to another little life.

Kurt gave the go-ahead, and I opened my hand. There were a few sharp pokes of tiny talons on my palm as she took to the air, and we watched as her fluttering flight became silhouetted against the moonlit sky, then disappeared into the black of the nearby forest.

Regrouping, Kurt and I put on our jackets and headlamps to check the other set of mist nets. About the size of a volleyball net but so delicate as to be almost invisible, mist nets have been used for decades to capture small birds. Each June, our Wisconsin Master Naturalist Volunteer Training Course experiences bird banding in the Moquah Barrens with Master Bander Jim Bryce. In daylight, his nets catch chestnut-sided warblers, brown thrashers, and clay-colored sparrows. Saw-whet owls are the smallest raptor east of the Mississippi—about the size of a robin and weighing just around 90 grams—and so the same nets work for them, too.

For many decades, northern saw-whet owls were caught only incidentally when nets were placed to catch other owls or nocturnal birds, and ornithologists thought that they were rare birds. Then someone decided to play a recording of the male’s song near the nets. Captures skyrocketed! We now know that saw-whets are fairly common across their range, although like most birds they have likely declined due to habitat loss over the past decades.

In the center of his three nets, which he deploys on dry nights from the last week of September through October, Kurt has a speaker set to play the owl’s loud toot-toot-toot call over and over. This sound is easily mistaken for the back-up-beep of heavy equipment, except that the owls are often calling at a time and place where no one would be working. The nets were empty on our second check, but earlier the speaker had blasted right at us as he worked to extract the little owl from the net.

This repeated call is the source of their name, since sharpening each tooth of a saw on a whetstone results in a repetitive sound. The owls make less well-known sounds, too. While exploring a series of recordings, I came across a vocalization nicknamed the “strangled cat whine.” I’ve heard this spooky sound numerous times in dark woods, and never known that it was just a flying kitten.

The owl in the net clacked her tiny beak in dismay at her predicament, but made no other sounds. Kurt is a Master Bander who has been banding birds since 2000, so with his experience it didn’t take long for the owl to be free of the net. Once inside his cabin, Kurt quickly prepared a leg band. Issued by the USGS Bird Banding Lab, the unique number stamped into the aluminum will allow this bird to be identified throughout her life and across the entire continent if she’s ever caught again. Unfortunately, federal funding for the banding lab’s important work is at risk of being cut.

Banding birds like this saw-whet owl has provided scientists with a wealth of information over the decades. Photo by Emily Stone.

Seven to eight percent of the 350 or so saw-whet owls Kurt has handled have already been banded, by him or someone else. These recaptures are an amazing source of information about the movements, ecology, and lifespan of the birds. Even if a bird isn’t recaptured, the measurements Kurt took of the owl’s weight, wing chord length, and age provide valuable data. This owl’s wing chord length of 136 mm, paired with a heavier weight, is what told us she was female. Male raptors tend to be smaller.

We also shone a UV light on the underside of her wing, where fresh feathers glowed hot pink. As feathers age, the UV-reactive pigment degrades, and older feathers look faded. This little owl was hatched just last spring and had only recently molted all her juvenile plumage into adult feathers, so they all glowed brightly.

Band-new feathers on this underside of the wings of this young saw-whet owl reflect lots of ultraviolet light. Photo by Emily Stone.

By this time next year she’ll have some bright and some faded feathers. Maybe Kurt will find her in his nets again. Maybe Mike Avara will discover that she’s raising chicks in one of his nest boxes. No matter what, her few minutes of discomfort at the banding station will help us understand more about her entire adorable species and what we can do to help them navigate a changing world.

Learn more about the volunteer opportunities with Mike and Kurt's saw-whet owl nest box and MOTUS tower research on the Museum's iVolunteer page: https://cablenhm.ivolunteer.com/saw-whet-owl-research

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is available to purchase at www.cablemuseum.org/books and at your local independent bookstore, too. Natural Connections 3 will be published in November 2025!

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. Our Fall Calendar is open for registration! Visit our new exhibit, “Becoming the Northwoods: Akiing (A Special Place). Follow us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.

Green Frogs Prepare for Winter

Golden birch leaves glittered across the portage trail as we pulled our canoe up at the landing. My paddling partner and I inhaled deeply of warm afternoon air that was sweetly scented with fall. Hoisting the canoe onto my shoulders, I started off down the trail. It went downhill from there, and not the good kind of downhill.

 

Off the end of a rotten boardwalk we found more mud...

One stretch the portage trail was an old railroad bed and actually quite nice to walk on!

First was the huge patch of sticky mud that sucked at my muck boots and threatened to throw me off balance. A puddle of unknown depth hid slippery rocks beneath the murky water. The next wet patch was spanned by a boardwalk, but the single plank was narrow, slimy, and bounced like a teetertotter where supports had become unstable. Finally, within sight of the next lake, movement near the toe of my boot startled me almost to the point of disaster.

 

Beaver-flooded portage landing.

Big black eyes with golden rims stared up at me from the slope of a rock. Crooked toes gripped the rough surface, and long hind legs braced for a quick escape. The green frog who had jumped out from underneath my boot perched motionless, as if that made them invisible.

 

Looking closer, I was captivated by the coppery shine of their skin, with indistinct dark spots. Despite their name, just a swath around their smile was green, like a smear of Halloween lipstick. Many frogs shift their skin to a darker color on cool days to absorb more warmth from the Sun, which is one reason green frogs (Lithobates clamitans) in the north are often brown.

From their large size, I guessed that this frog was female. Looking back on photos, I could confirm this by the comparing the size of her tympanum—the external ear structure—to the size of her eye. They were roughly equal in diameter. This membrane transmits sound waves to the inner ear. Male green frogs’ tympanums are larger than their eyes, although scientists aren’t sure what benefit that provides.

 

Female green frogs have a circular ear patch called a tympanum that it about the same diameter as their eye. On males, the tympanum is bigger. Photo By Emily Stone.

Throughout the trip—six muddy portages, five lakes, and then back again—we spotted gobs of green frogs at the landings leading into shallow, weedy water, and no frogs at the graveled landings with clear water. Green frogs feed by sitting and waiting for anything large enough to see and small enough swallow. Mud and plants make great habitat for these creepy crawlies, and therefore great habitat for frogs, who also lay their eggs among emergent vegetation.

While we reveled in the pleasantly warm weather, the golden birch leaves on the ground and orange-tinged cedar boughs along the shoreline were a constant reminder that winter is on the way. At home, I’ve been hearing lonely spring peepers call loudly before dawn every morning, from just outside my open windows. Like wood frogs, spring peepers spend the winter just beneath the forest’s leaf litter frozen solid. They are one of the first to wake up and thaw out come spring.

Green frogs can’t tolerate being frozen, and so must find a place to overwinter where they are guaranteed to stay liquid. Often this is simply at the bottom of a wetland or pond. They slow their metabolism and absorb a little oxygen through their skin. Sometimes they take a cue from their cousins and nestle into lake-bottom leaf litter, which gives off a little bit of warmth as it decomposes.

While spring peepers must wake up in a hurry, call like crazy, then rush to lay eggs in woodland pools that eventually dry up, green frogs can take breeding season at a more leisurely pace. Lakes sometimes take a while to thaw. Then the large mass of water takes even longer to warm up. Throughout it all, green frogs don’t have to worry about their eggs or tadpoles drying out before hopping away, even though they don’t start making their banjo-like plunk calls to attract mates until the peepers are almost done.

In fact, green frogs sometimes overwinter as tadpoles, and might not metamorphose until their second summer. By altering the composition of their muscle membranes, the tadpoles maintain their ability to put on a burst of evasive speed even in cold water. This helps them escape predators without wasting energy by moving quickly all the time. Dragonfly nymphs, diving beetle larvae, and water scorpions are all predators who also survive winter under the ice.

My canoe paddle bumped the bottom on one super shallow lake, and I started to worry. What would happen to the frogs and all those beings if this tiny water body froze to the bottom? I later read that green frogs have been observed gathering around springs where groundwater bubbling up will stay at a steady, unfrozen, temperature throughout the winter. They must be good at finding other warm microhabitats, too.

One last green frog watched from a wet rock as we paddled up to the final portage landing. Even more golden birch leaves had fallen overnight, and a lonely migrating loon wailed a farewell from across the water. Each of us was preparing for winter in our own way.

 

Getting out on as many paddling trips as possible before ice up is our way of preparing for winter!

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is available to purchase at www.cablemuseum.org/books and at your local independent bookstore, too. Natural Connections 3 will be published in November 2025!

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. Our Fall Calendar is open for registration! Visit our new exhibit, “Becoming the Northwoods: Akiing (A Special Place). Follow us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.

 

 

 

 

The Mystery of Mast Years

Last week I wrote about acorns clattering across my roof. As it turns out, nuts are raining down on many of your roofs, too! Commiserating over the loud, foot-rolling acorns makes me feel like part of an extended community. Are the oaks part of a similar community? And why are they suddenly attacking us with acorns!

Oaks are mast species, which means that all the trees in an area will produce a bumper crop of acorns at the same time, but only every two to five years. With hundreds of thousands of acorns available, the trees ensure that at least some of them will escape being eaten by chipmunks, squirrels, turkeys, blue jays, deer, and bears and survive until they can sprout and grow. This is known as predator satiation.

Red squirrels are seed predators on acorns.

In non-mast years, the acorn seed predators still survive, but at lower rates. When the oaks do mast, there aren’t enough critters to eat all of the acorns. The seed predators feed greedily and reproduce, but when there are few acorns the following years, their populations drop again. By being unpredictable with their mast years, oaks prevent seed predators from syncing up with the trees.

This same idea applies to parasites. Acorn weevils, knopper gall wasps, and acorn moths lay their eggs in developing acorns so that their larvae have an easy meal. A bacterial pathogen takes advantage of the holes they chew and causes “drippy acorn disease.” The result is the same as a chipmunk eating the seed, but the process takes longer. In addition, the parasites and pathogens are often closely tied to the acorn as a food source, and may not have other options. Chipmunks and other seed predators will eat from an extensive buffet of foods when acorns aren’t available.

While teaming up to satiate seed predators is clearly a good strategy for oaks, scientists are not so clear on how the trees coordinate, sometimes across hundreds of miles. It can’t be totally weather or resource driven, since variations in rainfall and temperature don’t fluctuate as much as the number of acorns produced. Certainly, an oak can’t produce tons of acorns if they are not healthy. But a year with plenty of rain doesn’t automatically result in acorns. During mast years a tree’s growth slows, so sometimes the trees need to put abundant resources toward making wood, not seeds.

One hypothesis about how oaks coordinate their mast years that seems to be gaining support in the scientific community is pollination efficiency. Oaks are wind pollinated. Their male flowers are dangly catkins that release pollen into the wind. The pollen needs to reach the pistils of the much smaller female flowers in order to fertilize the nascent seed. When oaks produce a ton of flowers at the same time and then have warm, dry weather, more female flowers will receive their dose of pollen. If the number of flowers oak trees produce fluctuates from year to year, this could translate into variable seed production, too. According to one study, this is true in “soft” climates, but not the Northwoods.

In harsh climates like ours, oak trees produce about the same number of flowers every spring. Having warm, dry weather that allows flowers to be pollinated AND to develop into acorns is essential, says Dr. Andrew Hacket-Pain who has used data from the Nature’s Calendar Phenology Project to study the correlation. A rainy spring, late freeze, or ice storm can easily ruin everything. Knowing how patchy storms can be in the Northwoods, I’m hesitant to believe that this could coordinate mast years across huge distances.

“In the old time, our elders say, the trees talked to each other,” wrote Robin Wall Kimmerer in her book Braiding Sweetgrass. Do they gossip about the weather like most Northwoods neighbors? Some mycologists theorize that the networks of mycorrhizal fungi who connect a forest by the roots may be the agent of coordination for mast years. “A kind of Robin Hood,” wrote Kimmerer, “they take from the rich and give to the poor, so that all the trees arrive at the same carbon surplus at the same time. Through unity, survival. All flourishing is mutual.”

Mice certainly flourish alongside acorns in mast years. The abundant food source means they have more babies. The same is true for the mice’s predators. Foxes, weasels, ticks, and even saw-whet owls may increase in number when mice are abundant. I’m excited for the potential uptick in owls, because the Museum has just started to recruit volunteers to help with a saw-whet owl study in Bayfield County. Check our calendar of events for details!

From mice to owls to chatting neighbors, oaks, and the mystery of their mast years, are at the center of our Northwoods community.

Author’s Note: Portions of this article are reprinted from 2015 – which was another mast year!

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is available to purchase at www.cablemuseum.org/books and at your local independent bookstore, too. Natural Connections 3 will be published in November 2025!

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. Our Fall Calendar is open for registration! Visit our new exhibit, “Becoming the Northwoods: Akiing (A Special Place). Follow us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.

A Summer of Loon Discovery

The pontoon bobbed in the water as I stepped onto the deck, clutching binoculars and trying to contain my excitement. Since moving to the Northwoods in the middle of winter, I had been waiting for the chance to see a loon, and my chance finally arrived in late May. The sunlight danced across the water as our boat left the dock, and we began our search. It wasn't long before we spotted the silhouette of a loon off in the distance, and headed for a closer look.

This loon was one of the most regal beings I had ever seen. They swam through the water with quick ease, head held high, only occasionally paying us a bit of attention. It was as if they knew they had our full attention, and as a result flaunted with a casual indifference as they floated around the boat. Their black-and-white spotted back glimmered right along with the sun reflecting off the water, highlighting their natural camouflage. We watched them preen their pristine feathers for a while, before they dove below the surface and left us behind.

An impressive loon swimming near our boat. Photo by Heaven Walker.

My next opportunity to see loons was on Lake Namakagon in mid June. As our pontoon slowly cruised through a marshy area of the lake, we kept our eyes scanning the scenery looking for loons. It wasn’t long before we spotted a loon, tucked into the dense reeds and aquatic vegetation, doing their best not to be spotted by us. They were in their nest with their neck and head extended low in front of them, body going as flat as it would go. It seemed to me like they were trying to be absorbed into the reeds to avoid our attention. As a highly aquatic bird, loons only go onto land to nest. By doing this, they are at a higher risk from predators, because they are very poorly adapted to moving on land. To help remedy this, loons nest very close to the waters edge for easy access to the nest, and for easy access to the water. This particular loon's body language on the nest told us that they were stressed by our presence, so we slowly continued on by–doing our best not to disturb them.

This loon's body language indicated they were stressed about our presence. 
Photo by Heaven Walker. 

That day on Lake Namakagon was the first time I saw loon chicks. The cute brown fluffballs with webbed feet were floating around with their parents, learning how to be a loon. I watched as one of the parents dove, and resurfaced with a small fish. Then it was a race from the chicks to see who could reach the parent first, and gobble up their meal. The parents continued to dive and bring fish to the chicks, and the chicks went so far as to attempt to dive themselves. But they never managed to be under for more than a few seconds before their fluffy feathers had them bobbing back to the surface. Diving wasn’t the only behavior the chicks were learning. As I continued to observe the chicks, one of them flapped their tiny wings and stretched vertically into the air. A wing flap! This is a preening behavior done by loons to maintain their feathers, and keep them aligned properly. It was quite adorable, and comical to see the chick wave their wing nubs about.

A baby loon practicing their wing flap. Photo by Heaven Walker

But it wasn’t until finding surprise loon chicks on Lake Owen in mid July that I truly became invested in loons. This pair of chicks were born later than typical, even by second nesting attempt standards. When I spotted them on a Loon Pontoon Tour, they gave me a glimmer of hope for having successful chicks on Lake Owen–as there had been no other chicks on the lake that summer. I instantly became invested in how they were doing. Week after week, I searched for them on the lake. Whenever it would take longer to locate the chicks on the lake, I would get worried that they had fallen victim to a predator. But then I would spot them swimming in the distance, and my worries would be quelled until the next week. As of late August, they were roughly five-to-six weeks old, quite sizable and seem to be doing well.

My summer observing loons was spent taking in all the new information I could on these fascinating birds. I witnessed adult loons call out in warning of an eagle flying overhead, and watched them track its flight as it went by. I watched as they took care of young, preened themselves, dove for food, and swam over to investigate other loons. They have become a new fascination, and I can thank my time in the Northwoods for that.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. Our Fall Calendar is open for registration! Visit our new exhibit, “Becoming the Northwoods: Akiing (A Special Place). Follow us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.