Monday, April 14, 2014

The Excitement of Spring

Spring is a season of change. All around me, things are changing color, new structures are being built, and a fresh cacophony of sounds fills the air. And that’s just inside the Museum! April is our exhibit construction month. Staff and volunteers demolished (and recycled) our old exhibit in just a few hours. Now the saws are humming, the cordless drills are whining, the carpenters are joking, and the paintbrushes are swishing.

A rainbow of geometric shapes grew to cover our dark green walls. Display boxes of all sizes and shapes, with hidden shelves for video equipment and holes for buttons and cords, seemed to spring up right out of the floor. A flat board metamorphosed into a flying superhero sidekick under the skilled brush of a volunteer artist.

Outside, a similar transformation is taking place. Bright sunshine and warm winds deconstruct winter’s snowdrifts. Eagles and osprey return as the rivers and lakes open up, and they gather sticks to refurbish old nests and construct new ones. Spiders are coming out of hiding to weave their webs, and some insects, suspended in a juvenile form all winter, will soon start metamorphosing into adults.

One color change I’ve noticed is the browning of hemlock needles in my yard. I’ve also noticed discolored evergreen trees along highways. Those I know are from salt spray off the roads. Passing cars splashed up salty water all winter. The evergreen needles absorbed some of the salty liquid. Once enough salt accumulated, it became toxic, and the needles died back from the tips.

I was a little more surprised at the trees in my yard turning brown, since they are not near any road. Serendipitously, a few days after I noticed my browning hemlocks, the Minnesota DNR published an explanation: strong, dry winds, many days of bright sunshine, and low relative humidity all contribute to the needles drying out so much that they die. It is possible I only noticed the damage recently because we’ve only had extended periods of strong sunshine recently.

Happily, the buds protecting new growth on trees are extremely tough, and tend not to experience winterkill. Even on the trees damaged by toxic road salt, new shoots will develop after spring rains wash the salt away.

So goes spring at the Museum, too!

Soon we will forget our winter-dried skin, our season with little color, our spirits that withered during the last (last!?) blizzard. Just about the time that frogs start peeping from the wetlands and warblers start chatting in the woods, first graders will start peeping in the classroom and visitors will be chatting in the exhibit. Come share the excitement of spring with us and our new exhibit—Nature’s Superheroes: Adventures with Adaptations—that opens May 1st!

For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI, at 13470 County Highway M. The current exhibit, “Deer Camp: A Natural and Cultural History of White-tailed Deer,” opened in May 2013 and will remain open until April 2014.

Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com


The balance of fire and ice

The morning stretched on like a cat basking in the sun. Freshly groomed ski tracks led us on a winding journey through golden-barked poplar stands, dense fir thickets, and across sunny meadows of windswept drifts. Wolf tracks, perfectly imprinted onto the smooth ski grooves, trotted along with us. Fox tracks floated across the icy crust; a remnant of last night’s mischief.

We seemed to glide on the boundary between fire and ice. The sunshine toasted our cheeks, foreheads, and tender necks to a crispy shade of red. Our skis swished along on icy snow, carrying our bodies through a dynamic temperature range.

Early spring is a time of shifting balance. The ice, which had been winning the battle for months, finally starts to weaken in the face of an intensifying sun. It is an age-old contest. The early stages of this fight make for absolutely fantastic spring skiing and snowshoeing. Warm sun for your face meets slick and supportive snow for your feet. The scenery isn’t half-bad either, when bluebird skies provide the backdrop for snow-dusted branches and clean white hills.

As the sun dipped low, more magic shimmered through. Glassy jumbles of ice panes on Lake Superior’s rocky north shore captured the last rays of light.  Out in the widening pools of open water, newly broken shards moved against one another in a gentle, tinkling, watery symphony.

By the next morning, the sun had redoubled its attack, and the ski trail softened in retreat. The glorious warmth on my face soon eclipsed the fading quality of the ski trails as a source of pleasure. I changed boots, and changed surfaces. Then, as a strip of wet blacktop road led me winding through hardwoods, the air held the scents of damp wood, wet leaves, and fresh life. Actually, the whole forest smelled like maple syrup.

It doesn’t matter that I woke up to an ice-encrusted car, or that another inch of snow fell throughout the day. It doesn’t even matter that yet another blizzard is hissing through the woods as I write this. The ice is on its way out. It may win another battle or two, but the sun will win the war.

“…Do you think there is anywhere, in any language, a word billowing enough for the pleasure that fills you, as the sun reaches out, as it warms you…?” –Mary Oliver, The Sun

For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI, at 13470 County Highway M. The current exhibit, “Deer Camp: A Natural and Cultural History of White-tailed Deer,” opened in May 2013 and will remain open until April 2014.

Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com


The Black-Masked Bandit


Let me take you back again to the sunny forest at the North End Trails near Cable, WI. A colorful line of thirty students, several parents, and a couple of teachers – all on snowshoes purchased with a grant from the Wisconsin Environmental Education Board – stretched out behind me on the trail.

The students could sense that the hike was almost over, and I’d already reassured some that it was all downhill from here. I was looking ahead to my next stop at the fox station, and eavesdropping on the students’ excited conversations behind me, when a teacher called out, “Hey, Miss Emily, there’s a dead mouse in this tree!”

Well, that stopped me in my tracks. “Are you serious!?” I called back, nearly bursting with excitement. “That’s awesome!” I stepped out around the students and started tromping through the deep snow back to where she stood. I waved to the kids in the front of the line to turn around and walk back with me.

There, nestled in the delicate fork of two sugar maple twigs, just above my eye level, was a very dead mouse. “That’s awesome!” I said again, probably striking fear into the hearts of the parents who were wondering how someone this weird came to be leading their children through the woods.

And then I started to explain: this mouse was most likely stored here by a bird called a Northern Shrike. When shrikes are able to catch more food than they need in a day, they store it for later use. Sometimes they’ll impale prey on thorns, or barbed wire fences. When those aren’t available, the fork in a twig will do.

Stored prey provides the shrike with food security, and will eventually get eaten when the hunting is poor. A male shrike with abundant prey impaled throughout his territory has a better chance of attracting mates and fathering successful nests, but this bird probably wasn’t worried about attracting mates. Breeding takes place north of 50 degrees latitude around the globe (that’s northern Canada). In winter, shrikes migrate only as far as necessary to find food, which often means they come to Wisconsin!

Surprisingly, these skilled predators are songbirds. Being songbirds, shrikes lack the sharp talons of raptors like hawks and owls. Being songbirds, shrikes have another weapon. Like the winged Sirens of Greek mythology, shrikes sing sweetly to attract other songbirds.

Once prey are lured in, shrikes attack with a solid blow, then finish the job by biting the neck, shaking, or repeated knocks to the skull with their sharp beak. Impaling prey on thorns or sticking them in forked twigs may seem brutal, but it is also a practical way to compensate for having delicate songbird feet that cannot grip food during dinner.
Sporting a black bandit-mask on their gray heads, Northern Shrikes look the part of a feathered villain.

More than half of a shrike’s diet is small rodents like mice and voles. Right now, most of those tasty little critters are safely hiding beneath a foot of snow in the subnivean layer. This unlucky mouse must have been caught running on top of the snow, above the relative safety of the subnivean zone. While foxes and owls have enough mass to break through the crust and dig for tunneling mice, shrikes do not have that ability.

We hadn’t seen a single mouse track on the snow in our two days of field trips, so this mouse might have been caught and stored a few days ago, before the last storm. It certainly looked a tad dehydrated.

After snapping a couple photos, I snowshoed back to the head of the line and kept the group moving. I’m not sure what those kids (or teachers and parents) thought of our discovery. A gross oddity? A cool animal sign? A scientific curiosity? In any case, the naturalist in me is thrilled to find evidence that a shrike is visiting our woods. I’m not the least bit sad that there is one less mouse running around, especially since it came to such an educational end.

“…And you know theirs is a decent task in the scheme of things – the hunters, the rapacious plucking up the timid like so many soft jewels. They are what keeps everything enough, but not too many…” –Mary Oliver from Bowing to the Empress.

For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI, at 13470 County Highway M. The current exhibit, “Deer Camp: A Natural and Cultural History of White-tailed Deer,” opened in May 2013 and will remain open until April 2014.

Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com


Monday, March 24, 2014

A Snowshoe Field Trip

The winter woods rang with the chatter of thirty or so third graders on a snowshoe field trip. Bright spring sunshine buoyed all of our spirits. This was my last group in a two-day marathon that brought 120 students and their teachers from Hayward, WI, out hiking on the North End Mammal Trail.

Along the 1.1 k Ridge Trail loop, just south of Cable, the Museum has placed about 20 life-sized wooden silhouettes of local mammals. The animals were cut out by students at Drummond High School, and their features were wood burned on by Museum volunteers, including local artist, Donna Post. We’re partnering with the North End Ski Club. Soon, we’ll also have a self-guided trail booklet with facts about each mammal.

Today, though, I had two backpacks full of wolf and fox furs, track molds, and a deer leg to teach the kids about winter adaptations of animals. At the top of the first big hill, I stopped to let the tail of the line catch up. “This is the best field trip ever!” exclaimed one student. “I’m not going to make it,” countered a short-legged snowshoer with a dramatic flop into a snowdrift. I reminded them to keep eyes and ears open, like wolves on a hunt, as we continued single-file, pack-like, down the trail.

“What’s that?” “A fake wolf!” “No, it’s a bear.” I chuckled at the conversation behind me in line. We stopped by the first visible mammal cutout (the chipmunk at the first station was completely buried in snow-- “hibernating”). Pulling out the wolf pelt, a wolf track mold, and a deer foot, we talked about the advantages and disadvantages of big feet. Appropriately, March is the “snow crust moon” in the Anishnaabe culture, and this gives a huge advantage to wolves with big feet over deer with small pointy feet, just like snowshoes help us humans stay on top of the snow.

A little farther on, my entourage spotted a flying squirrel attached partway up a hollow tree. These little nocturnal mammals have a fun behavioral adaptation for staying warm in winter – sharing body heat by snuggling together in groups of twenty or more. We did our own experiment, huddling in groups of six or so kids. I gave each cluster a thermometer and they had to try to get it as warm as possible. In just ten seconds they raised it ten degrees above the air temperature!

At another stop, we talked about the hunting strategies of long-tailed weasels. Like the small mammals they eat, the weasels spend a lot of the winter in the subnivean zone--in the air pockets and tunnels that open up at the boundary between earth and snow. Stored warmth from last summer’s sun radiates out all winter, and is trapped by the insulating snowpack. This helps to melt little chambers in the snow, and keeps the subnivean zone at a balmy 32 degrees.

I pulled two weasel furs out of my pack, and we all admired the excellent camouflage of their summer-brown and winter-white coats. Students pulled off their snow-crusted gloves to feel the amazingly soft fur, and we exclaimed at how skinny these creatures are – all the better for following mice into their burrows!

Then I asked the students to try and find the subnivean zone. A comical flurry of digging ensued, with colorful stocking caps disappearing down into holes. We never found the ground under all this snow, but we did discover an interesting series of icy and fluffy layers with different snow textures in the snowpack.

The wooden cutout of the black bear was easy to find, and students were eager to share their knowledge about bears. “What do you know?” I asked. We talked about mamma bears having their babies during hibernation, and male bears being more impatient to leave their dens in the spring. “So this bear must be a male,” observed one student.

My question “what do bears eat?” brought many answers. “Humans?” Well, no, but berries, fish, honey, insects, deer (fawns), seeds, and garbage to name a few. “So what’s that called,” I asked, “when an animal eats both plants and meat?” “Omnivore!” came the answer. Then we compared humans, with our omnivorous diets, to bears. I had the students feel their flat molars with their tongues. Those teeth are for grinding up carrots sticks, and bears have flat back teeth, too. Then we ran our tongues over our sharp front teeth. Bears also have sharp front teeth for tearing off bites of meat.

Finally, we ended up at the silhouette of the red fox. We talked about their fluffy, scarf-like tails, warm fur, and excellent hearing. Like owls, foxes can hear mice under the snow, triangulate their position, and pounce. Amazingly, scientists in the Czech Republic and Germany have discovered that foxes are more successful at catching mice in tall grass or snow if they face north to hunt. Over seventy-two percent of successful attacks were made when the fox was facing north, and foxes were also somewhat successful when they faced due south. Attacks from other directions were largely unsuccessful.

Why is the big question, of course, and scientists still don’t know for sure. “If you grow up to be a scientist,” I suggested to the line of bright-eyed explorers, “you could help figure it out!”

Whether or not any of them will grow up to be scientists, I have no idea. But at least we had a positive experience in nature that may inspire them to continue exploring and protecting the woods for years to come.

“To love what we do and feel that it matters – how could anything be more fun?” –Katharine Graham

For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI, at 13470 County Highway M. The current exhibit, “Deer Camp: A Natural and Cultural History of White-tailed Deer,” opened in May 2013 and will remain open until April 2014.


Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com

Welcome Theo!

“Who’s awake?  Me, too...” I love to hear the deep, powerful hoots of a great horned owl billowing through a snowy forest. Their stuttering rhythm -- hoo-h’HOO-hoo-hoo – seems to ask the question, then offers a conspiratorial answer.

I usually hear great horned owls in early winter, as they form pair-bonds and defend territories in preparation for nesting season. These large owls don't build their own nests, but take over nests made by crows, squirrels, hawks, or herons--whether their previous owners were ready to move out or not.

In late January and February things quiet down as the larger female owl lays from one to four, but most often two, eggs. She must begin to brood immediately, and then for the full 35 day incubation period, so that the eggs don’t freeze. Because of the necessity of constant brooding, great horned owls have a very strong pair-pond, and the attentive male brings food for the female, and eventually the chicks.

Why must owls nest in the depths of winter? It takes a long time for the owlets to grow up, and they require parental care well into July. If the owls waited until June, like the smaller birds, the young owls would not be strong enough before the next winter.

Just thinking of a 3 ½ pound owl, right now, sitting in a snow-covered nest with eggs or young chicks, makes me feel cold. But the owls are tough.

Excellent eyesight, precise hearing, and silent flight make great horned owls intimidating nocturnal predators. Their super strong talons (reported to crush prey with a force somewhere between 30 and 300 pounds per square inch) allow them to hunt such formidable prey as porcupines, geese, and scorpions. Speaking of tough, they are the only regular avian predator of skunks.

From their place at the top of the food chain, the only things great horned owls have to worry about are territorial disputes with each other, eagles, and snowy owls. Oh, and those pesky crows. Great horned owls are crows’ most dangerous predators, but if crows find an owl during the day, they will flock to it and harass it with the safety of numbers. One author hypothesizes that the long hours of darkness during their breeding season helps to protect the owls from crow harassment.

As tough as they are, owls do have one more predator to worry about – humans and our vehicles. Road ditches – where trees for perching meet grass with small rodents – are tempting places for owls to hunt. When you throw your apple core out the window, it attracts even more rodents, which lure  even more owls. Unfortunately, when an owl is focused on its prey, it won’t notice your headlights closing in.

Most of the Museum’s collection of owl specimens were picked up on the side of the road. Their wings and feet make great educational tools, but we’d much rather have live birds in the wild.

Not every car-owl collision ends in the salvage freezer, though.

Last summer, Joe Papp, a Museum volunteer who has experience with raptors, noticed a great horned owl in the ditch along Highway 63, just south of Drummond, several days in a row. When Joe was finally able to catch the owl, it was obvious that its wing was injured, and the owl couldn't fly.

Well, Joe brought the owl to Katie Connolly, our Museum Naturalist/Curator, and she delivered the owl into capable hands at the Raptor Education Group, Inc., in Antigo, WI, where they have licensed rehabilitators.

“Unfortunately his wing had been broken at a joint, and had already begun to heal, leaving him crippled and unable to fly ever again,” Katie told me. “The rehabilitators believe he was struck by a car on Highway 63 and began eking out a living next to the roadside because he couldn't fly away. We can only imagine him running down mice and other rodents to eat!” she added with a chuckle. That’s just one more example of owl toughness.

Because the owl can’t fly, he wouldn't have a fair shot at surviving in the wild, and is non-releasable. Six months after the accident, the male great horned owl, now named Theo, is safe and well fed in his home in the raptor mews at the Cable Natural History Museum. With Katie as his trainer, Theo will soon be an education bird who can help kids of all ages learn about the amazing adaptations, and toughness, of great horned owls.

We’ll be posting updates about Theo’s training progress, construction of his new home in the Museum’s outdoor classroom, and public programs where you can meet him, on our website (www.cablemuseum.org) and Facebook page.

While you wait to meet Theo, don’t forget to keep an eye—and an ear—out for his wild cousins. Who likes owls?  Me too.
For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI, at 13470 County Highway M. The current exhibit, “Deer Camp: A Natural and Cultural History of White-tailed Deer,” opened in May 2013 and will remain open until April 2014.


Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com

A Walk Through the Summer Woods

I’m going to take my imagination on a walk through the summer woods. Would you like to come with me?

The day begins with a cacophony of birdsongs, crashing through my bedroom window. Robins shout “Cheer up, cheerily, cheer up, cheerily” on incessant repeat. Northern parulas buzz up a scale, then alternate with a call that sounds like Porky Pig’s classic “Th-th-th-th-That's all, Folks!” All the while, the blue-headed vireo announces his presence with short, loud phrases: “See you. Be seeing you. So long.”

Soon, bright sunshine follows the birdsongs into my room. “Hello, sun in my face.
Hello, you who make the morning…and spread it…into the windows of, even, the miserable and crotchety,” muses poet Mary Oliver. Rolling over, I look at my watch: 5:30 a.m. I wipe the sleep out of my eyes and put on shorts, a tank top, and hiking shoes. After all, Henry David Thoreau claims that “An early morning walk is a blessing for the whole day.”

Sunshine glows through vibrant green treetops, and dew clings to the grass as we grab our binoculars and head down the driveway. In the big maple tree, we can hear the northern parula buzzing away. First I listen, tilting my head like an owl or a fox for better triangulation. When I think I know where he is, I lift my binoculars to my upturned eyes and search for the little singer.

The sun, rising higher, begins to feel warm. There! A sunbeam catches his gorgeous blue head, yellow throat, and…OW!!! Binocs slam to my chest as I swat three mosquitoes that simultaneously penetrate the skin on my neck, my eyebrow, and my lower lip. Time to get moving.

We cross the road and duck through a gateway of little hemlocks onto the trail. The cool shade feels good since elsewhere sunbeams and dew have combined to raise the heat index. Sun flecks play on the forest floor, highlighting tender green leaves pushing up through last fall’s brown carpet. A patch of bunchberry flowers glows white in the diffuse light, and I hurry toward them for a closer…aaarrrrgh!

My face went right through the sticky net of a spider web. Clinging strands send shivers down my spine, and delicately tickle the nerves of my nose, cheeks, hair, and neck. Not far from my right ear, I notice the web owner herself, looking fairly large and not so happy with me. Every night, orb-weaver spiders like her eat, recycle, and re-spin their webs using only their sense of touch. I just ruined a work of art that took hours to create.

Forgetting the bunchberry, we forge on, still picking spider silk out of our hair, and also swatting mosquitoes. Naturally, they land almost out of reach on the backs of our arms, between our shoulder blades, on ankles and knees. These are female mosquitoes looking for a blood meal. Once satiated, they will rest for a few days to let the blood digest and its nutrients (our nutrients!) develop into eggs. After just two or three days, they will lay those eggs and look for a new blood host. The cycle repeats itself until the female dies. On average, each female lays 200 eggs during her short life.

More spider webs lie in wait across the trail, so I pick up a stick from the moist duff to wave in front of us. The swinging stick keeps most of the webs off my…ewww! Something squishes under my fingers, and I feel sticky slime coat my skin. Turns out, my spider-stick was also the home to a small slug. I rub my hand in the dirt to get rid of the slimy feel.

Soon we emerge from the deep shade of the forest into an emerald green field. Wild roses bramble along the edge between forest and field, the purple canes of blackberries are dusted with five-petaled, snowflake-white flowers. “There were violets as easy in their lives as anything you have ever seen or leaned down to intake the sweet breath of…” (Mary Oliver) They cluster in the grass at the edge of the trail, their purple faces delicately fringed with white beards.

As I rise from smelling the violets, I notice something on my shin. A tiny nymphal black-legged tick (aka deer tick) is crawling up my leg. Actually, two…no, three little ticks had quested right onto my ankle. It is amazing that I even noticed these little disease vectors, since they are just the size of a poppy seed.

Flicking off the ticks, and frantically brushing at any suspicious tickle, we hurry down then trail, suddenly sweating profusely in the sweltry heat. It has become so hot that even the birds have stopped singing.

And here, my friend, is where I will part ways from our imaginary field walk. The grass may be greener in June, but green grass isn’t everything. Right now, today, in March, there is clean, white snow covering the ticks. Some mosquito adults hide out in diapause—a state of suspended animation—while the larvae of other mosquito species are trapped beneath several feet of lake ice. The orb weaver died last fall, after creating a thick, silken sack for her eggs. As for me, it is twenty degrees, the sun is out, the bugs are gone, and I just bought new skis! Carpe diem!

“Now comes the long blue cold. And what shall I say but that some bird in the tree of my heart is singing.” –Mary Oliver

For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI, at 13470 County Highway M. The current exhibit, “Deer Camp: A Natural and Cultural History of White-tailed Deer,” opened in May 2013 and will remain open until April 2014.


Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com

Thursday, March 6, 2014

Martens and Wind


Fierce gusts of wind rocked the treetops above me, sending shivers down their trunks. Among the boles of swaying aspens, maples, and firs, I skied with one ear to the sky. Twigs clattered, snow plopped, and cold wood fibers moaned up and down the musical scale. One tree almost buzzed with a high-pitched popping, while another groaned from deep within. I listened carefully to determine the location of the loudest trees, and to gauge their ability to strike me if they came crashing to the ground.

Although the bluster threatened above me, it didn’t quite reach all the way down to the swooping hills and rippled snowpack. I felt protected in the understory of this forest. My eyes were scanning for animal tracks in the days-old snow, but I only saw signs of other skiers. Deep drifts and bitter temperatures have driven many creatures down into the next level of protection: the subnivean layer.

Fluffy snow captures summer warmth still radiating up from the ground. A thin zone opens up under the snow, right at the surface of the ground. Here, the temperature stays at a fairly stable 32 degrees Fahrenheit. Compared to a negative 45 degree wind chill at the surface, that feels pretty balmy!

American martens are one of the many creatures that exploit the subnivean microclimate. These small weasels tunnel through the snow to find food, stay warm, and escape predators. Phil Manlick, a Master’s student at UW Madison, has been studying the “Habitat-mediated foraging and predation risk in reintroduced American Martens.” Recently he gave a dinner lecture on the topic at the Rookery Pub and Fine Dining near Cable, WI. One of his hypotheses is that martens need lots of structural diversity – lots of fallen logs – in their habitat to help them gain access to the subnivean layer.

Once under the snow, martens can forage along the log-lined runways where red-backed voles, mice, shrews, and squirrels also travel. When satiated with a tasty meal, martens have been known to curl up in the den of their prey for a nice warm nap. The snow is an excellent blanket for this lean mammal, who stores little fat and burns lots of fuel to stay warm. Snow also provides cover from other predators. The diets of foxes, fishers, and bobcats overlap with martens’ diets, and those larger carnivores will kill martens to eliminate competition.

American martens were extirpated from Wisconsin in the 1920s, due to unregulated fur harvest and widespread habitat loss. In 1986, wildlife managers developed a marten recovery plan with the goal of reestablishing two self-sustaining populations of martens in the Chequamegon-Nicolet National Forest. But even with cooperation between the Wisconsin DNR, the US Forest Service, and the Great Lakes Indian Fish and Wildlife Commission (GLIFWC), and multiple reintroductions, marten populations in the Chequamegon National Forest are not rebounding as well as wildlife managers and researchers hoped. Phil is trying to figure out why.

Although he’s still mostly in the data collection phase, preliminary results indicate that one issue limiting the American martens’ recovery in the Chequamegon National Forest might be poor juvenile survival. Adults are doing fine, he says, but the young martens, kicked out of their parents’ home range after just a few months, may not be finding enough high quality food to make it to adulthood.

Phil’s research techniques involve gathering hair samples from martens as they explore PVC tubes baited with beaver meat and equipped with a brush. By comparing the ratios of stable isotopes of nitrogen and carbon in the martens’ bodies to the ratios of those isotopes in their various prey species, Phil can get an idea of what martens are eating. Other researchers also identify animal remains found in marten scat to identify specific prey.

The surprising results are that in northern Wisconsin, martens’ diets consist of 40% shrews and 30% deer. In contrast, healthier populations of martens out west and in Minnesota eat many more red-backed voles and squirrels. Why might eating shrews and deer be a problem? Shrews, like the martens themselves, don’t store fat for the winter. With an extraordinarily fast metabolism, shrews must feed voraciously night and day. This makes them the skim milk of the small mammals.

Deer might seem like an improbable food source for a two-pound marten, but evidently, martens are feeding opportunistically on winter-killed and wolf-killed carcasses. The trouble is that deer carcasses are a risky food source. Fishers, wolves, coyotes, and other scavengers are attracted to those same banquets, and make things dangerous for the martens. That competition with other species may be another important factor limiting the martens’ recovery.

Phil suspects that habitat quality has an impact on both food availability and competition. During his summer habitat surveys, Phil found that martens need “nasty forests that you don’t want to trudge through.” By which he means forests with lots of blow downs, snags, large trees (greater than 39 cm diameter), and coarse woody debris. If further data analysis supports that hunch, it might influence how foresters manage the landscape in the future.

Thinking back to those trees groaning and swaying in the tempest above me, it might not be a bad thing if a few of them fell down...after I’ve skied past, of course.

“But these are the woods you love, where the secret name of every death is life again…”  -- Mary Oliver, from Skunk Cabbage

For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI, at 13470 County Highway M. The current exhibit, “Deer Camp: A Natural and Cultural History of White-tailed Deer,” opened in May 2013 and will remain open until April 2014.


Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com/.