Flight

I love things that help me get a new perspective on the world, so I always request a window seat. Taxiing to the runway, my face pressed to the clear plastic window, I watched a flock of snow buntings swoop in unison above the grass. White flashed on their wings. There was grace in the unconsciousness of their flight.

Birds are so well adapted for travel through the air that their movements can seem effortless. Even when we see how hard they are working, the power in an eagle’s wings and the skill of a hummingbird’s maneuvers fill us with a sense of awe. Human-designed flight was not so easy.

In the years since Icarus flapped his waxy wings toward the sun in ancient Greek mythology (and fell into the ocean when they melted), humans hadn’t had much luck trying to copy birds. Paradoxically, the great success in human flight came when we stopped trying to mimic natural flyers and began designing from scratch, says Professor Spedding, of the University of Southern California.

Now there I was, ready to take to the air, casually fulfilling the dream of flight with millions of other people today. We turned down onto our runway and sped up. As the force pushed me back into the seat, I imagined what it must be like to be a loon – running hard across the lake, splashing and pushing with broad feet, until finally achieving enough speed for liftoff. Even when I was no longer jostled by the bumps of earth, I was still pressed back into my seat by the acceleration.

Loons have the heaviest wing-loading of any flighted bird, so they, like airplanes, must gain speed in order to generate enough lift to leave the ground. They must maintain that speed, too, or risk a crash landing. Have you ever seen a loon fly slowly? Me neither. Also like commercial airliners, loons need their wings mostly for long-distance trips, and use wide-open spaces for take-off and landing. This allows both planes and birds to survive with limited maneuverability.

I’m likewise fascinated to see a bird’s-eye-view of the landscape – to follow familiar rivers, highways, lakeshores and forests in an effort to understand them from a new perspective. Today, however, my view was blocked as we rose through a thick layer of bright white clouds.

Thankfully, the pilot has a sophisticated instrument panel that helps guide our course. Birds, too, have a sophisticated set of tools for navigation. Besides using landmarks during the day, they use the rotation of the stars, the orientation of earth’s magnetic field, and the angles of polarized light at sunset.

New research from the Max Planck Institute for Ornithology in Seewiesen, Germany, has added weight to the hypothesis that homing pigeons (and probably other birds, too) use smell to navigate home. Every place smells a little different, and breezes coming from different directions carry that information to the pigeons. The birds can essentially create a smell map in their head that helps them navigate back home. Amazing! But I’m still glad my pilot is using a GPS.

Although humans only achieved flight when they stopped trying to copy birds, now that we’ve figured it out, engineers are looking back at the more experienced flyers to solve all sorts of problems. For example, jet aircraft engines used to “choke” at supersonic speeds due to air moving around the engine instead of through it. The peregrine falcon – which can dive at over 200 mph – provided a solution. Specialized cone-shaped bones near its nostrils, called baffles, deflect shockwaves of air and allow peregrines to keep breathing. Jet engines now have similar cones in their engines.

Despite the clouds, we found Chicago, and with our loon-like limited maneuverability, swung wide over the lake to start the landing pattern. As we slowed down to land, the plane used another bird-like feature on the wing. Nearing the ground, slats on the front of airplane’s wings dropped down. According to Wikipedia, this “allows the wing to achieve a higher than normal angle of attack – and thus lift – without resulting in a stall.”

On a bird, the alula--a small projection on the leading edge of the wing--serves the same purpose. It is essentially the bird’s thumb, and its three-to-five feathers can be moved freely. When flying slowly or landing, the bird can move the alula slightly upward and forward, giving it the same advantages as the airplane slats in slower or higher-angled flight.

Future airplanes may use a sharkskin-like paint job or butterfly scale-like coverings to reduce drag. Seabird-like moveable wings might improve efficiency with gusts. Humans continue to look to nature for more ways to improve our flight. Even rubber made from Kazakh dandelions may one day provide a more sustainable material for landing gear.

As the old-fashioned rubber tires bumped onto the runway beneath me, I was grateful for the chance to view the world from a new perspective. But I realized that my relatively effortless trip was made possible by years of innovation – just like the snow buntings’ effortless grace came only after eons of evolution.

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 Dandelion Smile

A chilly breeze whipped around my head. Even a pale sun peeking through racing clouds did not seem to improve the temperature. Head down, I hurried toward the post office. Then, a spot of color made me stop and smile. A single yellow dandelion and its star of vibrant, toothy leaves nestled into the snow-flattened grass.

I’ve always loved dandelions. They popped up every summer in the kingdom of make-believe that was my yard, and created a sea of sunshine in the farmer’s hayfield across the back fence. Every spring I still pick one of the hardy flowers to give to my mom for her late April birthday. Unless I’ve flattened it in a card to send through the mail, she still sticks dandelion in a little vase on the sill above the kitchen sink.

As a kid, I continued picking dandelions all summer long. I’d split the stems lengthwise and watch as they coiled into beautiful curlicues when dunked in cold water. I soaked the fuzzy blossoms in water and made “lemonade” that I never drank. I almost hyperventilated while trying to blow every parachuted seed off the stem to make a wish. And every t-shirt I owned was stained with little brown circles from the juicy stems.

Even today, despite my awareness that dandelions are invasive weeds, I can’t help admiring their tenacity. And I’m not alone. Buddhist monk, Thich Nhat Hanh, shared this poem (written by a student) in his book, Peace is Every Step.

I have lost my smile,

but don’t worry.

The dandelion has it.

So I smile whenever I see those cheerful weeds. Sometimes I even brave their bitterness and eat young leaves in salad. Other folks swear by the sap as a remedy for warts or foot fungus. Turns out, the dandelion may be more useful than I ever imagined!

The Kazakh dandelion (Taraxacum kok-saghyz, a relative of the one in your yard), is an excellent source of natural rubber. The milky sap in the root is so high in latex that one field of dandelions produces as much latex as the same size plot of rubber trees. In addition, the quality of dandelion latex is exactly the same as latex from a rubber tree, and can be substituted one-for-one in the rubber formulation. To top it all off, dandelion latex does not seem to trigger allergic reactions!

Russians discovered this amazing dandelion in the early 1930s, in Kazakhstan. They tried to develop it as a domestic source of rubber. During World War II, when the Japanese controlled the supplies of rubber from Southeast Asia, researchers in the United States, Germany, Sweden and Spain all jumped on the dandelion-rubber bandwagon. In the U.S. alone, land grant universities in 40 states conducted research on this lowly plant.

Most research came to a halt after the war ended in 1945. Today, an internet search for dandelion rubber reveals that at least three separate tire companies are partnering with research institutions to make this new source of rubber viable on a commercial scale. Germany's Fraunhofer Institute for Molecular Biology and Applied Ecology is working with Continental. Bridgestone is working with the Program for Excellence in Natural Rubber Alternatives at Ohio State University. Multinational tire manufacturer, Apollo Vredestein, also thinks dandelion rubber has potential, and is collaborating on the project with KeyGene.

Despite the many benefits of dandelions – they grow like weeds on many soil types, reproduce like weeds with lots of seed, and thrive in northern climates instead of sub-tropical forests – there are some obstacles, too. Dandelion juice transforms from a liquid to a solid on contact with the air – a process known as polymerization. This means that processors must use turpentine to chemically extract the latex from dandelion roots.

To eliminate the enzyme responsible for polymerization, German scientists at the Fraunhofer Institute engineered a special virus. According to a Discovery News article, “Once inside, the virus deleted the offending genetic sequence from the Russian dandelion's DNA. Pop the head off an infected dandelion, and the latex begins to flow freely.” (Watch out, Mom!  My shirts will have more than just little brown circular stains!)

It worked. But in Europe, creating transgenic dandelions is pretty controversial. Now German researchers are using traditional selective breeding techniques to accomplish the same thing. At the same time, Continental is working with the researchers to build the first ever commercial-scale processing plant. (Hopefully they are also developing ways to make sure the super-seeds don’t escape into our yards!)

Maybe in the future, that field of dandelions across the back fence won’t be full of weeds. It will be full of a cash crop, harvested by the same machines used to pull tulip bulbs. The sticky sap, once a stain on my shirt, will instead help my airplane land safely in Germany so I can go for a ride in a car with dandelion tires. That might even make me smile.

“What is a weed? A plant whose virtues have never been discovered.”

--Ralph Waldo Emerson

The Weird Ones

The scent of snow fills the air, and the hissing plops of wet snow falling off the trees fills my ears. The woods, and its inhabitants, are transitioning between fall and winter. It’s the same for me, as I jog down the road in my summer hat and winter gloves, wishing for ski season to arrive.

Early fall was a time of vibrant colors and lots of action. Colors have faded a bit now. If you have lived in the north for a while, you may have come to appreciate the subtle gold of a tamarack swamp, or the rich browns in an grove of oaks as they extend the fall color season. But have you ever stopped to think about how weird those two trees are?

Tamaracks are conifers, bearing their seeds in cones just like their relatives the pines, spruces, and firs. But conifer isn’t our first choice for describing pines – we’d rather call them evergreens. When we do that, though, tamarack doesn’t fit. It is the only deciduous (losing its leaves seasonally) conifer in Wisconsin. Oaks, in contrast, are in a group known as broad-leaf trees, most of whom are deciduous. Yet oaks cling to their leaves.

Why would a tamarack lose its needles? Why would a pine keep its needles? And why does the oak keep its dead leaves?

There is adaptive value in each strategy, otherwise they would not persist. Needles are really just modified leaves, better suited to low nutrient, low moisture situations. They have basically the same parts as a maple leaf, but everything is more tightly packed and protected. The stomata (pores for gas exchange) hide in a groove, protected from dry winds. A waxy outer layer helps to prevent water loss. By retaining green, chlorophyll-filled leaves all year, evergreen trees can take advantage of any warm days to photosynthesize, and save themselves the trouble and nutrient expense of growing new leaves each spring. They replace only about a third of their needles per year.

On the other hand, broad-leafed deciduous trees, like maples, grow large leaves with a lot of surface area for photosynthesis. The broad leaves also result in a lot of water loss. This is fine when it is raining, but not when it is frozen. Although trees use enzymes to protect leaves from freezing while they are still photosynthesizing, that only works for so long. Then, frost-damaged leaves would be a liability as an entrance for disease.

Why would tamarack combine the two strategies and lose its needles?

Well, we don’t know for sure, but my favorite theory is that it has something to do with how far north the tamarack’s range extends. On the Winter Solstice this year, Duluth, MN, will only have 8 hours and 32 minutes of sun. In Fairbanks, Alaska, near the northern edge of the tamarack’s range, the sun will shine weakly for 3 hours and 42 minutes. Most of the tamarack’s habitat is in the middle of that range. What good are green needles if there is little sunshine? By building more delicate needles that don’t have to withstand harsh winter conditions, tamaracks can save a little energy.

Likewise, what good are the dead, brown leaves of an oak, even with sunshine? Oaks are a broad-leaf tree, but, oddly, they hang onto their leaves until heavy snow knocks them off, or until new leaves push them out. Most deciduous trees (including tamaracks) cut their leaves off by growing a protective abscission layer on the end of the twig, and then encouraging the leaf to skedaddle with digestive enzymes or a new layer of cells.

In contrast, oak leaves start to grow an abscission layer soon after new leaves form, but do not finish the process until the next spring. Scientists call this retention of dead stuff “marcescence.”

Plant physiologists agree that marcescence is a juvenile trait, associated with young trees and newer branches. This makes sense, since the young aspens in the field near my house are still holding onto their leaves. And understory trees, which tend to be younger, always seem to change colors later in the fall.

Marcescence also may be juvenile in terms of evolutionary history. In southern regions, some oaks are evergreen. Our northern oaks may be in transition from being fully evergreen to being fully deciduous. Maybe they are not done yet…or maybe they like where they’ve paused!

Although there are tasty new buds waiting to come out in the spring, this year’s dead, dry, crinkly oak leaves are not very palatable, and that may deter deer and moose from nibbling on the new growth. The tardily deciduous aspens probably gain that benefit, too.

Another hypothesis is that the oaks are saving their leaves until spring. When the leaves fall, they will provide the tree with nutrient-rich mulch for the growing season, instead of the leaves decomposing throughout the winter. The leaves dangling from lower branches may also act as a snow fence, trapping extra moisture for the tree.

Of course, there is no way for us to know for sure just what the oak is “thinking” as it rustles its skirt of leaves in the middle of a blizzard. Nor do we understand what the tamarack is “planning” when it turns golden, and then bares its knobby twigs for the winter.

As with humans, the weirdest organisms are often the most interesting. At least, that’s what I hope, since some of you probably think I’m weird to be wishing for ski season in October!

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/.

Woolly Weather

A blustery fall wind swept away any warmth from the pale sun. Brown and yellow leaves skittered across the pavement. As I bent down to dip my hands in the lake, my arm (wrapped in fuzzy fleece) brushed the seed head of a burr marigold—so named because the cheery yellow flower matures into a cluster of pokey stick-tight seeds. Yet another sign of the season…

Distracted, I meandered back toward the car, picking little two-pronged seeds out of my armpit as I went. Then...whoa!  Something caught the corner of my eye, and I pulled my foot back from its next step. There, in the middle of the parking lot, was a woolly bear caterpillar. Not the most exciting find, but it would have been unpleasant for both of us if my shoe had continued on its original path.

I’ve always enjoyed seeing these fuzzy, black and brown-striped critters. As a kid I tortured them—poking one to watch it curl into a ball…patiently waiting until it uncurled...and the poking it again. You’ve probably had your own encounters with these cute little critters, no matter what age you happened to be. A few years ago, while I was teaching in Maine, my class found a woolly bear’s hairy cocoon in the woods. The students just shook their head at my enthusiasm for the discovery.

Seeing this woolly bear didn’t strike me as anything spectacular, but I took some photos anyway, because a friend had asked me about the caterpillar’s famed weather predicting skills. My research turned up a great story about that, and so much more.

Back in 1948, Dr. C. H. Curran, curator of insects at the American Museum of Natural History in New York City, wanted an excuse to get out of the city and enjoy the fall colors. He decided that the question of woolly bears’ weather prediction skills needed some field research (sounds like a great excuse to play hooky from work to me!), and took his wife a nearby state park. They gathered as many woolly bears as they could find, and measured the sizes of the black and brown stripes. This was so fun that they invited friends the next year, and began calling themselves The Original Society of the Friends of the Woolly Bear.

For eight years they “gathered data” in the beautiful fall woods. At first, it seemed like they were on to something. Several years in a row, the brown stripes took up more than a third of the caterpillar’s thirteen body segments, on average. Folklore says that wider brown stripes forecast milder winters, and that did indeed play out for Curran. Then came the year that two groups of caterpillars in neighboring habitats gave opposing forecasts. That year, Curran gave up.

As it turns out, some scientists now think that the width of the brown band IS related to the weather—of the previous spring. Each time the caterpillar gets too big for its skin and molts, one black segment changes to a brown segment. So, a w-bear who starts eating early (they are generalist feeders who eat a variety of plants), during a mild spring, will have a wider brown stripe by the following fall. A caterpillar who gets a late start, perhaps due to snow in April (not that we know anything about that!), will likely have fewer brown segments before the growing season ends again.

So, with one riddle solved, we’re ready for another one. Why do you see so many woolly bears crossing the road this time of year?  To get to an overwintering site, of course! Like many northern critters (bears, for example), woolly bears are short-distance migrants who need to travel a little ways to find a nice place to spend the winter. And they can get there fast (for a caterpillar) traveling at 0.05 miles an hour, or about a mile a day.

Beneath a rock, under a log, in a bark crevice—almost any protected place will do for an overwintering woolly bear. Warmth is not a major factor, since these little guys will freeze solid, and thaw, and freeze again, many times throughout the winter. On a warm day, they may even get out and crawl around.

If a tomato spent the winter like a woolly bear, it would soon be mush. But woolly bears use chemicals known as cryoprotectants to safeguard living tissue against damage from freezing and thawing. Woolly bears who live in the arctic (the species we know as well as some relatives) may take 14 years to complete their life cycles. They freeze solid every winter, and grow just a little bit during each brief summer.

Our Wisconsin (or Minnesota) woolly bear only needs two years to complete its life. In spring, it will thaw and resume eating. Once large enough, the caterpillar spins itself a cocoon using silk and its own hairs. In two weeks, it metamorphoses into a pale yellow Isabella tiger moth. In another two weeks, the moth will mate, lay eggs, and die.

Tiger moths, in the family Arctiidae, are amazing, colorful creatures in their own right. Some tiger moth caterpillars eat toxic plants, just like monarch caterpillars, in order to protect themselves against predators. The toxin persists in the adult moths, who use bright warning coloration to tell potential predators that they taste bad. Since one of their main predators—bats—can’t see colors in the dark, the moths emit ultrasonic sounds to warn bats of their unpalatability.

All the moths are surely dead by now, and their offspring, the caterpillars, are racing toward their overwintering rocks. I hope the one I almost stepped on found a cozy place in the leaf litter. With snow in the forecast, I’m glad I overwinter in a house. I wonder how mild or harsh this winter will be?  I wish a woolly bear could tell me!

The Forest Rainbow

Sunlight streamed through a golden canopy of maple and poplar leaves, bathing the hiking trail in warm energy. The group chatted merrily, their lively conversations keeping pace with eager hiking boots, bright moods reflected in bright clothes. Pink and purple leaves on the maple-leaf viburnum added color to the understory, while the last remaining berries on blue-bead lily and blue cohosh stalks provided accents. Overall, the fall forest was a rainbow of color.

But not all the most interesting colors were immediately obvious. As my boot scuffed the dry brown leaves on the side of the trail, a glimpse of vivid color caught my eye. Buried beneath the fading leaf litter was a bright red fungus. As I brushed the crinkly leaves aside, my fingertips relished the smooth, slippery texture of the mushroom’s surface.

Aptly named the scarlet waxy cap, clusters of this beautiful mushroom has been livening up most of my hikes lately. Earlier in the fall, their particular shade of red, with yellow on the margin of the cap, blended in perfectly with fallen maple leaves. Now, although buried under more leaves, the colors stood out distinctly.

Since this mushroom is easy to identify, it is tempting to harvest it for my kitchen. Indeed, it is reported as “mild tasting” and is eaten throughout its habitat in Europe and Asia. However, since some mycophagists (people who eat mushrooms) in North America have reported adverse reactions to the scarlet waxy cap, I have decided to enjoy it solely in the woods.

After examining that first patch of waxy caps, I began to see them peeking up among leaves all along the trail. Then I started seeing fungi everywhere! Lichens (composed of fungus and algae) encrusted all the trees, shelf fungi gave trunks interesting silhouettes, and rows of white turkey tail mushrooms lined every fallen log.

Turkey tails are some of most common mushrooms found on wood in the world. They are a type of bracket fungi, meaning that they form thin, leather-like and leaf-like structures in concentric circles. When you flip a scarlet waxy cap upside down, you find rows of bright yellow gills. But, on the underside of a turkey tail, you find tiny pores.

It is the upper surface of a turkey tail mushroom that provides its name, though. Concentric rings of brown, orange, maroon, blue, and green remind us of the iridescent tail feathers on a wild turkey. While not as bright as the waxy cap, the turkey tail has subtle beauty, and is worth close examination. It also has medical uses.

Turkey tail mushrooms have been used to treat various maladies for hundreds of years in Asia, Europe, and by indigenous peoples in North America. Traditionally, our ancestors boiled mushrooms in water to make a soothing tea. Records of turkey tail brewed as medicinal tea date from the early 15th century, during the Ming Dynasty in China. A few years ago, my Aunt Nan used turkey tail tea to boost her immune system during a battle with cancer, and she outlived the doctor’s predictions by several years. Last summer, a promising clinical study showed that the turkey tail mushroom (Trametes versicolor) improves the immune systems of breast cancer patients.

As I examined a log covered with little bracket fungus, I noticed that some of them looked purple around the margin instead of the typical white. When I broke one off to examine it more closely, I found a very different mushroom!

The plain white and cream cap of a violet-toothed polypore hides a gorgeous lavender underside. If you tilt it, the color becomes almost iridescent as light bounces around the brightly colored pores. While not medicinal, this mushroom always makes me smile. I can’t wait to bring my four-year-old niece Kylee mushroom hunting, so she can look for her favorite color on every fallen log.

What she won’t see as easily is the true body of the fungus. Scarlet waxy caps, turkey tails, and violet toothed polypores are saprophytic fungus, meaning that they decompose wood to obtain nutrients. The mushroom you see is simply the reproductive structure, tasked with releasing spores. The true work is done by a network of fungal cells (called mycelium) penetrating the decaying wood. One analogy is that the mushroom is like an apple, with the mycelium is like the tree.

You can sometimes find a web of black or white mycelium under the bark of a tree, beneath a rooting log, or under thick leaf litter. By some accounts, the world’s largest known organism is an interconnected web of genetically identical mycelium in Oregon’s Blue Mountains. This honey mushroom occupies 2,384 acres of soil (approximately 1,665 football fields) and could be as ancient as 8,650 years old.

All those mycelium are extremely important links in the food chain, since they play an enormous role in recycling nutrients from old plants and animals into new plants and animals. Can you imagine a forest without fungi? In the absence of wildfire (another decomposer) dead trees and plant debris would pile up horribly, and new trees would not have enough nutrients to grow.

As our hike ended, the chatter continued right on in to the cars. What fun it was to take a closer look at all the components in the forest’s rainbow on a beautiful fall day!

Migration Season at Hawk Ridge

“Hold it like an ice cream cone,” instructed Gail Johnejack, Education Director at Hawk Ridge Bird Observatory, as she skillfully wrapped her hand around mine, and guided my fingers into a careful grip on feathers and legs. When she transferred the bird into my care, I could feel the heartbeat in my own skin. A breeze ruffled the Sharp-shinned Hawk’s feathers, and I imagine we were both eager for it to continue its long migration journey. Beyond the bird stretched the city of Duluth, and the shimmering water of Lake Superior.

Hawk Ridge in Duluth, MN, is one of the top five hawk migration sites in North America for overall numbers and diversity of species. Each fall, about 82,000 raptors pass through this bottleneck on their southern migration. Understandably reluctant to cross a large body of water, the birds funnel southwest along the shore of Lake Superior. The high, rocky outcrop of Hawk Ridge Nature Reserve makes a great viewing platform, and people come together from all over the country to watch the migration here.

Harry, a Hawk Ridge volunteer, lives in central Minnesota, and drives three hours to volunteer a few days each week between September 1 and October 31. Harry is retired, like many volunteers, and enjoys interacting with the other main type of volunteer—college students fulfilling requirements for courses.  Harry loves his job, because “volunteers and visitors both find commonality and community in the birds – they draw us all together as a group. It keeps me young!” says Harry.

The natural setting is also a bonus. Bright sunshine, a warm breeze, and a terrific view are a stunning combination. Even chilly gray days have their own beauty. Harry likes the full spectrum. “When we hawk watchers arrive on the first of September we look down on the city in full summer green. By the time we leave on October 31, most of the leaves are gone. We are blessed with seeing the complete transition of fall.”

I gripped the Sharp-shinned Hawk carefully, amazed at both its sturdiness in my hand, and also the strength I could sense in its muscles. Erik Bruhnke, Count Interpreter, positioned himself just over the cliff, camera in hand. All day, Erik alternates between spotting and identifying birds, answering visitors’ questions, and taking photos of hawk releases. He is a wealth of information, and one of the reasons Harry loves his volunteer gig.

“I watched birds all my life, but I’m not a bird watcher,” Harry says humbly. “I’m just trying to become one! One of the benefits of Hawk Ridge is that amateurs can really learn from all the real birders that are here.” Erik is equally thrilled the arrangement. “Teaching is the best way to learn. Working here really helps me learn about birds on a deeper level.”

I learned a lot from Erik, too. For instance, the bird in my hand, a Sharp-shinned Hawk, is an agile and acrobatic flier, able to navigate dense woods at high speeds by using its long tail as a rudder. Short, rounded wings help Sharpies zip through tight spaces after small birds. During migration, they leave the dense forests of their northern nesting grounds and take to the open sky.

“Now you’re going to be the Statue of Liberty,” Gail instructed. “Hold your arm up high. When Erik counts to three, give it a little toss into the air.”

I raised my right arm high—thrilled to hold such an amazing creature for even a few seconds—and thrilled to be a part of its freedom. “One...two...three!” counted Erik. I released my grip with a gentle toss, and watched in awe as the hawk took flight. It swooped down below the cliff, and darted around trees before disappearing from sight. Close on its tail, three more hawks materialized out of the north, and zipped past the eager crowd.

Today, with a south wind, I wasn’t expecting to see much. Why would raptors fly with such a headwind? But, to my great delight, Sharp-shinned Hawks, American Kestrels, Merlins, Peregrine Falcons, Ospreys, and even Northern Goshawks zoomed past low enough to identify with the naked eye. Rain a few days ago delayed migration and created a backlog of birds. Now, the southerly winds force the birds to fly low, within easy view, and where they can be baited into the nets that researchers have set up.

Researchers carefully extricate each bird from the net, take a variety of measurements, and attach a numbered band to its leg. About three percent of birds banded here are recaptured. “Our utmost priority is to keep the raptors safe,” assured Gail. “When a raptor is captured for banding, it is held for a very short time, and then we let it get on its way.”

The bird I just released has a band, and if researchers recapture it again, Hawk Ridge will be notified. Since I sponsored the bird’s release, (with a donation to the private non-profit Hawk Ridge Bird Observatory) they will also let me know that this bird I connected with is alive and traveling.

“It’s hawk migration season!” exclaimed Gail. “We love having people come and visit and learn about this great migration event!” If you would like more information on the migration at Hawk Ridge, visit their website: www.hawkridge.org or find them on Facebook, or on their blogspot—http://hawkridgeblog.blogspot.com/.

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/.

Sharpies at Hawk Ridge (combined)

“Hold it like an ice cream cone,” instructed Gail Johnejack, Education Director at Hawk Ridge Bird Observatory, as she skillfully wrapped her hand around mine, and guided my fingers into a careful grip on feathers and legs. When she transferred the bird into my care, I could feel the heartbeat in my own skin. A breeze ruffled the sharp-shinned hawk’s feathers, and I imagine we were both eager for it to continue its long migration journey. Beyond the bird stretched the city of Duluth, and the shimmering water of Lake Superior.

Hawk Ridge in Duluth, MN, is one of the top five hawk migration sites in North America for overall numbers and diversity of species. Each fall, about 82,000 raptors pass through this bottleneck on their southern migration. Understandably reluctant to cross a large body of water, the birds funnel southwest along the shore of Lake Superior. The high, rocky outcrop of Hawk Ridge Nature Reserve makes a great viewing platform, and people come together from all over the country to watch the migration here.

It’s not easy, though, the migrants of are often tiny specks against the blue. Raptor biologists here have a special trick for getting close-up views of the hawks – bait. Using a technique a lot like fishing, researchers pull the string on a lure to make it look like an injured bird. When a raptor swoops down for an easy meal, it becomes tangled in one of a series of nets. Researchers carefully extricate it from the net, take a variety of measurements, and attach a numbered band to its leg. “Our utmost priority is to keep the raptors safe,” assured Gail. “When a raptor is captured for banding, it is held for a very short time, and then we let it get on its way.”

About three percent of birds banded here are recaptured. Based on the data collected from recapturing banded birds, sharp-shinned hawks migrating over Hawk Ridge generally head southeast to Illinois, and then southwest toward east Texas and Mexico, following the prevailing wind pattern.

Sometimes naturalists bring a recent captive down from the remote banding station so that folks on the overlook can get a better view. Moments after we arrived, two naturalists called everyone over to see a couple “sharpies” in hand. To prevent the hawks from hurting the humans or themselves, the naturalists held their wings, tail, and legs gently but firmly in the fist of one hand. The birds, both hatch-year females, looked quite calm.

Sharp-shinned hawks are the smallest hawks in North America, and have the biggest size difference between males and females. Females are up to one-third bigger than males, and this size difference means that they focus on different sizes of prey. Males tend to hunt smaller birds, such as sparrows, while females can concentrate on larger prey, like robins. This has two big advantages: males and females do not compete for the same food source, and chicks can get appropriately sized food as they grow.

During the first few weeks after hatching, the female sharp-shin broods the chicks while the male hunts and brings in small songbirds. He typically removes and eats the head before delivering the meal. As the chicks mature, the female joins in the hunting and brings larger prey for the hungry fledglings.

Sharp-shinned hawks are agile and acrobatic fliers, navigating dense woods at high speeds by using their long tail as a rudder. Short, rounded wings help them zip through tight spaces after small birds. During migration, they leave the dense forests of their northern nesting grounds and take to the open sky.

To help make the journey easier, these and other hawks will ride thermals, which are rising pockets of warmer air, formed by the uneven heating of the surface of the Earth. Thunderheads are visible thermals, where clouds of water droplets show just how high the warm air is climbing. When you see turkey vultures or other birds soaring in lazy circles without flapping, they are riding thermals.

For every mile a bird rises on this avian elevator, it can coast downwind seven miles without flapping. Still, sharp-shinned hawk’ migration from the top of this continent to the bottom takes strength, endurance, and stored energy. In order to be ready for the journey, these small hawks grow furiously—going from egg to adult size in just over 7 weeks.

I gripped the sharp-shinned hawk carefully, amazed at both its sturdiness in my hand, and also the strength I could sense in its muscles. Erik Bruhnke, Count Interpreter, positioned himself just over the cliff, camera in hand. All day, Erik alternates between spotting and identifying birds, answering visitors’ questions, and taking photos of hawk releases. He is a wealth of information.

“I watched birds all my life, but I’m not a bird watcher,” Harry a Hawk Ridge volunteer, says humbly. “I’m just trying to become one! One of the benefits of Hawk Ridge is that amateurs can really learn from all the real birders that are here.” Erik is equally thrilled the arrangement. “Teaching is the best way to learn. Working here really helps me learn about birds on a deeper level.”

Harry is retired, like many Hawk Ridge volunteers. He enjoys interacting with the other main type of volunteer—college students fulfilling requirements for courses.  Harry loves his job, because “volunteers and visitors both find commonality and community in the birds – they draw us all together as a group. It keeps me young!” says Harry.

The natural setting is also a bonus. Bright sunshine, a warm breeze, and a terrific view are a stunning combination. Even chilly gray days have their own beauty. Harry likes the full spectrum. “When we hawk watchers arrive on the first of September we look down on the city in full summer green. By the time we leave on October 31, most of the leaves are gone. We are blessed with seeing the complete transition of fall.”

And I’m thrilled to help this hawk transition back to its journey. “Now you’re going to be the Statue of Liberty,” Gail instructed. “Hold your arm up high. When Erik counts to three, give it a little toss into the air.”

I raised my right arm high—thrilled to hold such an amazing creature for even a few seconds—and thrilled to be a part of its freedom. “One...two...three!” counted Erik. I released my grip with a gentle toss, and watched in awe as the raptor took flight. It swooped down below the cliff, and darted around trees before disappearing from sight. Close on its tail, three more hawks materialized out of the north, and zipped past the eager crowd.

“It’s hawk migration season!” exclaimed Gail. “We love helping people experience this great event!”