Thursday, February 23, 2023

The Wandering Grosbeak

The vehicle pulled off to the side of the snow-packed gravel road was the first clue that we were about to see something exciting. I steered our car over as well, and my parents and I peered into the woods.

Movement and bright colors soon resolved into yellow birds with black and white wings hopping around a pile of black oil sunflower seeds. What luck! My parents had driven up from Iowa, and then we’d all traveled over a hundred miles from northern Wisconsin to the Sax-Zim Bog Important Bird Area in northern Minnesota in order to see unusual birds. Here they were!

Evening grosbeaks are colorful members of the finch family. They got their name not because they are the color of the setting sun, but because English settlers thought the birds only came out of the woods to sing at sundown. French settlers reportedly gave them the more accurate name of le gros-bec errant, the wandering grosbeak. These bright birds travel widely toward the best winter food sources in movements known as “irruptions.”

Here in Sax-Zim Bog, numerous bird feeders provide endless pounds of black oil sunflower seeds to entice grosbeaks into easily viewed locations. Out in the winter woods, evening grosbeaks are attracted to the large seeds of deciduous trees like maples, ashes, and boxelders.

As my parents and I checked out several different feeding stations in the bog, we were treated to the antics of flocks of 20-40 evening grosbeaks flitting between feeders and trees and making the sunny air ring with their bright, warbled calls.

While those birds were fun to watch, even more impressive flocks have been spotted at feeders in Washburn, Ashland, and Clam Lake, Wisconsin. Ryan Brady, conservation biologist with the Wisconsin DNR, has been posting photos and videos of more than 100 evening grosbeaks in his yard for most of the winter.

And yet, that abundance is deceiving. Between 1966 and 2019, evening grosbeak populations declined by an estimated 74 percent. The causes of this decline are not fully understood, but likely stem from changes in both their winter and summer food sources.

Spruce budworms – the destructive caterpillars of a little brown moth – are a favorite baby food for evening grosbeaks. Grosbeaks are so good at detecting spruce budworms that an influx of the birds is often humans’ first clue to the start of an outbreak. The birds stuff their chicks full of the juicy, protein-packed larvae, and experience excellent nest success.

After a couple years of high caterpillar numbers and high bird reproduction, budworm outbreaks wane naturally. Large numbers of birds are faced with food shortages. Cycles of natural budworm outbreaks, and shifts in how much humans try to control outbreaks through aerial spraying, impact how much baby food grosbeaks have access to from year to year, and decade to decade.

Back in the 1800s, evening grosbeaks were mostly a western species. In the early 1900s they started to move east, mostly in winter. It was around this time that boxelder was increasing in popularity as an ornamental tree, and would have provided a steady winter food supply.

In the 1950s, their winter food got another boost. During the post-World War II baby boom, boxelder trees became a favorite landscaping tree in new housing developments. While boxelder was native to much of New England, it became much more common and moved north into parts of Maine and nearby Canada where it hadn’t been before. In addition, the 1970s saw extensive spruce budworm outbreaks. The dramatic increase in both their summer and winter food at this time may have meant that evening grosbeak populations were unnaturally high at the start of the period of decline.

Logging, spraying for budworm, and diseases like West Nile likely ended the grosbeaks’ period of abundance. Now climate change threatens to disrupt our forests even more. As balsam firs and spruces shift north in the face of warming temperatures, the summer food sources for evening grosbeaks might decline enough that they can no longer breed south of Canada.

None of that was at the forefront of our minds as we watched the birds in Sax-Zim Bog. Evening grosbeaks were not the only attraction. Eager Canada jays swooped in to lick peanut butter off sticks. A boreal chickadee took their turn at the fatty feast, too. Red-breasted nuthatches snacked on seeds. Pine grosbeaks added their beautiful rosy hue to the bird rainbow. And a northern hawk owl perched stoically in an aspen tree.

For this winter at least, we can enjoy a colorful visit from le gros-bec errant.

Pine Grosbeak

Northern Hawk Owl

Red-breasted Nuthatch
Boreal Chickadee

Canada Jay

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at and at your local independent bookstore, too.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is now open with our exciting Growing Up WILD exhibit. Follow us on Facebook, Instagram, YouTube, and to see what we are up to.

Thursday, February 16, 2023

“The Last of Us” in Real Life

With a firmly packed trail under my feet, I could let my eyes wander. Blue sky peeked through gaps in the red pine canopy, and the orderly rows of their trunks made pleasing patterns against the snow. On this hike, though, I wasn’t looking for uniform trees. This was a scouting trip for an upcoming interpretive hike, and my eyes were peeled for special or unusual bits of nature that would make participants go “wow!”

Through a brushy patch I noted a young boxelder tree with winged samaras still drooping from the twigs. Across the trail, a cherry sapling sported the wrinkled growths of black knot fungus, and the leaves of a young oak tree fluttered in the wind. This could be a stop where I talk about easily visible clues to winter tree identification, I thought.

A few steps down the trail, another oak sapling caught my eye. This one was only chest high and barely half-an-inch in diameter where it disappeared into the snow. And it was hairy.

My second look revealed that the twigs were covered with small, shiny, brown domes, and from most of these domes sprouted a forest of little black clubs. Their shape reminded me of Earth tongue fungi and pin lichens, both of which I’ve written about previously. As I finished hiking the loop, I spotted these odd-looking twigs everywhere!

On a recent snowshoe hike, I found many twigs on oak saplings that were covered in scale insects who had been parasitized by fungi. Photo by Emily Stone.

The domes I recognized. Several years ago I spotted the same type of critter on an ironwood tree. These were scale insects. Like their relatives the aphids, scale larvae insert sucking mouthparts (called stylets) into the leaves and start drinking. In order to get enough nitrogen, they must drink an excessive amount of the sugar-rich sap, which they concentrate and excrete as “honeydew.” Ants take advantage of this just like they do with aphids, and can often be seen drinking honeydew off the scale insects.

As the nitrogen and sugar fuel their growth, the scale larvae molt. With each molt, their bodies become larger, and their legs become smaller. Finally, in late summer before their legs completely disappear, the nymphs walk back down the leaf stalk and onto their winter home on the twig. They build their waxy, protective shells, and do not move again. Spring brings maturity, egg laying, and death.

Death, in this case, came early. I sent a photo of the scale insects with clubs erupting from their shells to Britt Bunyard. Britt is the editor of Fungi Magazine and a frequent field trip leader for the Museum. I affectionately refer to him as “my mushroom guy” and send most fungi-related questions his way. He studied entomology as well, so this mystery was perfect for him.

Here’s an up-close view of what I believe to be the same pair of organisms. Photo by Michael Bohne, USDA Forest Service,

Britt wrote back that these fungi were most likely Cordyceps clavulata. Cordyceps fungi are well known to plant pathologists and agronomists because, according to Britt, “they are one of the rock stars of biocontrol of insect pests on economically important crops.” In other words, these fungi are on our side, and help control pests!

Cordyceps are fungi who parasitize insects (mostly). First, a spore encounters a tasty host, then it sends web-like mycelium throughout the body of the insect to digest it. Finally they send their club-like reproductive structure up into the air to release spores. The cycle repeats.

According to Britt, there is only one known reference to Cordyceps fungi parasitizing scale insects. This could be a unique observation and important to science! I have marching orders to collect samples for further research.

You may be familiar with Cordyceps, because HBO’s recent zombie thriller “The Last of Us” is purportedly about Cordyceps that switch from attacking insects to attacking humans. I’m not sure because I haven’t seen it. I don’t watch the horror/apocalypse genre, especially when it’s based in nature. (Read about the science behind the sci-fi here.) For one, I do NOT want to be thinking about that stuff while I’m in the woods. For two, real nature has plenty of suspense and gore if you know where to look! Luckily these real-life fungi are the good guys! They’ve just taken care of what looks like a huge outbreak of scale insects in this section of forest.

As I searched for more details, I discovered that oak lecanium scale insects become pests most often in cities. Sometimes it’s because the heat island effect in cities both stresses out the trees and allows the scale insects to develop faster. Sometimes it’s because spraying for mosquitoes has killed off the predators and parasites who would control the scale insects. I called around to nearby landowners, and no one admits to having sprayed for mosquitoes in this forest. My friend who hikes there in the summer confirms that there are plenty of skeeters on these trails. So, the cause of the outbreak remains a bit of a mystery.

Happily, mysteries are fun to teach about. Not only did I find something interesting to show the visitors next week, I discovered something that made even my mushroom guy go “wow!” Now that’s a successful hike.

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at and at your local independent bookstore, too.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is now open with our exciting Growing Up WILD exhibit. Follow us on Facebook, Instagram, YouTube, and to see what we are up to.

Thursday, February 9, 2023

Counting Cubs

With bright sunshine to provide at least the appearance of warmth, single digit temperatures didn’t phase us much. Hand and foot warmers took the edge off, too, as did the brisk pace set by college students from University of Wisconsin Stevens Point’s (UWSP) Wisconsin Black Bear Project.

The students weren’t following a designated trail, instead they were following the faint beeps of a radio collar worn by a female black bear in her den.

For over 30 years, students and professors from UWSP have conducted research on the seasonal movements, habitat selection, and reproduction of Wisconsin’s black bear population. During that period, bear numbers have risen from 9,000 to 24,000. The researchers’ hard work has contributed significantly to the body of knowledge about black bears in Wisconsin, and informs bear management, too.

On this late January morning, a small group of Wisconsin Master Naturalist volunteers were lucky enough to join a reconnaissance mission. The sow bear we headed toward had been caught in a barrel trap last fall and fitted with a collar. Although her age was unknown, she weighed more than 150 pounds at the time of capture, (she topped out the scale) which means she was big enough to have cubs. Students monitored her movements using radio telemetry equipment, and noted when and where she entered her den. Now, the question was, did she have cubs or yearlings?

Black bears have a unique reproductive cycle. Mating occurs in late May and June, and eggs are fertilized then. But after each one develops into a tiny ball of cells called a blastocyst, they hang out on pause for five months. If the sow puts on enough weight during her fall period of hyperphagia, then the blastocysts implant into the uterine wall in November and develop rapidly. If the sow has a lean fall, then her body won’t put her through the rigors of motherhood.

Cubs are born in January, weighing only a pound. According to the North American Bear Center in Ely, MN, “newborn cubs are smaller, relative to their mother’s size, than the young of any other placental mammal.” While it’s rumored that mama bears stay asleep while they give birth and discover a cute surprise in the spring, this is just folklore. Mother bears wake up to give birth and care for their young, although they do their best to conserve precious energy and fat stores.

At a respectful distance from the den, we paused to let the college students go ahead. Assistant Professor and Bear Project leader Cady Sartini answered our questions, and prepared us for what we’d see.

Cady Sartini talks about bear biology. Photo by Michael Mucha.

Like many mamas, this bear had excavated a den in sandy soil under roots and brush in a spruce bog. Some bears have been known to just lie down and let the snow cover them, but this expectant mother was a little more picky. Only females are radio collared and ear tagged, Cady told us, since the project is mostly interested in bear reproduction. Males range more widely, and don’t stay with their offspring. Cubs spend their second winter with their mother, too, and, ideally, female cubs who survive to be yearlings get a collar before their mom kicks them out.

A student returned to our group with exciting news—they could see the mama bear’s nose, and hear noises from at least two cubs! Most likely, the young cubs were hidden behind mama, away from the drafty entrance. From previous experience, researchers know that it’s important to observe a den for 20 minutes or so to make sure that they’ve given the cubs a chance to be heard. 

Confirming the presence of cubs or yearlings is essential because the research team plans to return in March. They will anesthetize the adult. The cubs will be counted, sexed, weighed, and aged by measuring the length of the hair between their ears. If there are yearlings in a den, the process becomes more complicated. They would be anesthetized along with the adult, and any female yearlings would be fitted with collars. Knowing what the researchers will encounter, and being able to plan for it, is key to making the process go smoothly. 

Caption: One of the student researchers from UW Stevens Point looks and listens for signs of cubs in an active bear den. Photo by Cheri Schultz.

Carefully and quietly, a few at a time, Master Naturalists were allowed to approach the den. Cady had explained that the bear would know we were there, but she would be trying her best to stay asleep. Disturbing hibernating bears is something that should be done as little as possible, and with valid research goals in mind. Just by nursing young, a female will lose around half a pound a day, and waking up wastes valuable energy.

Under the snow, the den hole seemed sandy, dark, and damp. The mother bear lay with her face buried and a paw over her ear, just as you would if you were trying to sleep in. From behind her came the pulsating grunts of warm, comfortable, nursing cubs. This sound tells mom that everything’s fine and she can stay right where she is. (You can listen to these sounds in the Museum’s current exhibit, Growing Up Wild.)

Later, one of the Master Naturalists reflected that “it is one thing to read that a sow bear gives birth to cubs while she hibernates and quite another to peer into the small opening of a bear’s den mid-winter, see her snout and a paw, and hear her mewling cubs from the darkness of the confines beyond. This was a gift I believe we all received with great gratitude.”

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at and at your local independent bookstore, too.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is now open with our exciting Growing Up WILD exhibit. Follow us on Facebook, Instagram, YouTube, and to see what we are up to.

Thursday, February 2, 2023

Patterns in Sand

Sand scuffed under my boots as I hiked up and out of the river bottom. The desert stream we’d eaten lunch near was running high after winter rains near Sedona, AZ. As we climbed, the chill I’d felt while sitting dissipated, and I paused to take off a layer. Hiking in a tank top in January was quite a treat.

“Check it out!” I exclaimed, as the patterns on the steep bank next to the trail caught my eye while I stuffed my long sleeves in my pack. Pausing and looking down is often a recipe for spotting something fun, and this time was no different.

The soil on the bank was sculpted into miniature towers, buttes, spires, and hills. Some high points—standing an inch or two tall—were capped by a pebble. That hard surface would protect the sand below from the erosive force of raindrops, just like a layer of harder cap rock forms the top of a full-size butte.

Little flecks of dark brown lichen covered some of the petite hills, their odd shapes fitting together like puzzle pieces. In one patch, pale pink lichen flakes glowed in contrast. Truly minute bits of lichen coated the sand in a black film, and tiny tufts of green mosses stuck out of them like beard stubble.

“Cryptobiotic crust,” I’d learned to call this strange microcosm when I first worked in the desert of Southeast Utah after college.

Cryptobiotic crust is the community of tiny living things who glue together the surface of some soils. Cyanobacteria move in first. While often referred to as blue-green algae because of their ability to photosynthesize, they are actually ancient bacteria who played a part in creating the oxygen-rich atmosphere we enjoy today.

Although dormant when dry, the sheaths surrounding cyanobacteria cells swell and produce filaments as they absorb rainwater. Damp filaments weave among the soil particles and grab on. As the cyanobacteria dry out, the filaments secrete complex sugars which harden into glue.

Over many years and many cycles of wetting and drying, a fragile crust develops. It prevents the sand from blowing away in dust clouds or becoming shifting fields of dunes. “Crusts are the glue holding this place together,” claims my well-worn Naturalist’s Guide to Canyon Country.

But the desert isn’t the only place woven together with life.

This past October, on one of those last sunny days, I hiked the Lakeshore Trail in the Apostle Islands National Seashore. The path begins above Meyer’s Beach and winds northeast through the woods.

Over millions of years, water has carved the reddish sandstone bedrock into headlands and inlets, cliffs, and of course the sea caves. If you’re willing to hike up and down through steep ravines, along narrow boardwalks, and up several sets of stairs, the rewards are spectacular.

Lured by the lake’s cerulean blue and the craggy form of a tenacious red pine, I ventured out on a narrow headland with cliffs falling away on three sides and spectacular views of the sculpted rocks on the headland next door. The view commanded me to pause and take a long look. Before turning to leave, I closed my eyes and inhaled a deep breath of sun-warmed pine needles.

I’d laid my trekking poles near the base of the red pine tree to leave my hands free for my camera, and as I bent to pick them up, a new view—no less spectacular than the waves and cliffs—recaptured my attention. “Check it out!” I exclaimed.

Tiny forests of mosses poked up between pale sand grains. Carpets of bluish lichens protected little hills, and pixie cup lichens raised their chalices as if waiting for the right vintage of raindrop. Here, miles from the desert, was another community of cryptobiotic crust holding together sand as the stone falls apart. The sandstone on the South Shore is five times older and gets twice as much rain, but otherwise is not so different from some of the rocks of the Colorado Plateau.

Crouching in front of the little garden—protected from crushing footsteps by the twisted roots of that tenacious pine—my eyes roamed through the miniature landscape on an epic adventure. Climbing hills, seeking rest in the soft swales, discovering new life forms on every peak, I traveled while my feet stayed still.

Looking up from Lilliput, I saw the patterns of diversity and connection in that small patch repeat themselves in the forest, across the landscape, and throughout the world.

Author’s Note: Portions of this article were originally published in 2019.

Emily’s award-winning second book, Natural Connections: Dreaming of an Elfin Skimmer, is now available to purchase at and at your local independent bookstore, too.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. The Museum is now open with our exciting Growing Up WILD exhibit. Follow us on Facebook, Instagram, YouTube, and to see what we are up to.