Friday, May 23, 2014

Bird Muscles and Migration

Sometimes it takes a lot of willpower to put on my running shoes and take off down the road after a day at my desk. Today, despite (or maybe because of) the intermittent cloudbursts and beckoned by the ovenbirds’ rapid-fire teacher-teacher-teacher songs ringing through the trees, it felt like a necessity. As the cool drops misted my face and the raindrops swallowed sunlight while abandoning themselves to gravity, I felt multiply rewarded for my effort.

“What makes aerobic exercise so powerful is that it’s our evolutionary method of generating that spark,” according to Dr. John Ratey. “It lights a fire on every level of your brain…”

Then, to add to the magic of the moment, the flute-like song of a wood thrush floated sweetly above the treetops. Henry David Thoreau wrote, "The thrush alone declares the immortal wealth and vigor that is in the forest. Whenever a man hears it, he is young, and Nature is in her spring.”

A few more minutes down the road, and a bird flew about five feet in front of my nose. I stopped to look as it landed at eye level. Bird watching (and listening) is one of my favorite parts of running. Even without binoculars I could tell it was a yellow-rumped warbler, yet another early spring migrant. Soon a whole flock moved through the branches.

The ovenbirds, the thrush, and the other warblers are in the midst of incredible, ancient migrations from their wintering grounds in Central America to their summer nesting territories in the U.S. and Canada. Their ultramarathon skills put my little four-mile jog to shame, but then again, they are better designed for it.

Birds save energy during flight by having short humerus (upper arm) bones and lengthening their forearms with featherlight structures that are, well, feathers. You can appreciate the difference this makes when you switch from heavy winter boots to your light summer sandals. Every extra ounce your leg has to lift makes each step that much harder! So, light, hollow wing bones, as well as having the wing muscles located on the chest, concentrates weight close their body and their center of gravity.

By selecting easily digested foods like berries, seeds, and insects, birds were able to shrink their stomachs, too. (Just compare a bird gut to the gut of an herbivorous cow.) Birds also traded heavy teeth and jaws for lightweight beaks.

With less room needed for their digestive tract, birds have room for more air. Their unique lung system allows birds to route air through their lungs, instead of in and out like we do. This makes their fresh air exchange incredibly efficient, and allows species like bar-headed geese to fly over the top of Mount Everest—without supplemental oxygen!

In the fading sunlight, the flock of warblers flitted effortlessly as I huffed and puffed down the road. I confess, I have a bit of lung envy.

But it isn’t just that they take in fresh air more efficiently. The hemoglobin in birds’ blood has a high capacity to bind oxygen. Their blood actually delivers more oxygen per unit than ours. Another chemical, myoglobin, takes up oxygen from the blood and delivers it to the cells. This dark red protein is what colors the dark meat on your Thanksgiving turkey. The combination of all these things gives birds an incredibly high VO2 max, a measure of aerobic capacity that will sound familiar to many skiers.

Not only do I wish I had their lung capacity, I also wish I could eat like a bird. Right before migration, birds feast like crazy, and can double their weight in as little as ten days. And it’s healthy for them! The fat gained during this period of “hyperphagia” is stored in masses under the skin on the abdomen and upper chest. It can fuel nonstop flight for three days and nights. Then the birds are lean again.

While birds have adaptations for athleticism that I can only dream about, we do share one behavioral adaptation: both the birds and I choose to exert ourselves when it is cooler to avoid dehydration in the heat of the day.

“Birds are not likely driven by the logic of what they do,” biologist Bernd Heinrich philosophizes in his book, Why We Run, “instead, they are motivated by powerful urges. They behave in ways that feel right and pleasurable to them. Feelings of pleasure are a byproduct of evolution that makes healthy organisms do what helps them survive and produce offspring, in the same way that fear makes them shy away from danger.”

What makes birds begin their migration, Heinrich says, “is probably not fundamentally different from what motivates me to jog down a country road on a warm sunny day.” And, by the end of our respective migrations, both the birds and I feel like singing.

For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI! The current exhibit, “Nature’s Superheroes—Adventures with Adaptations,” opens in May 2014 and will remain open until March 2015.

Find us on the web at to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot,


Shimmering silver globules clung to slender twigs, reflecting the meager light from a leaden sky. More silver globules of a very different density pelted the leaf litter, the brim of my hat, and occasionally my cold-reddened ears. I suppose it has snowed on pussy willows before, since they are one of the earliest signs of spring, but the driving pellets of sleet on fuzzy flowers and tender skin felt like an affront to us both. It was enough to give me a headache.

Just a few days prior, I’d been admiring this patch of pussy willows as it was bathed in warm sunshine. I’d also squinted at the aspen flowers silhouetted against a bluebird sky. And I took note of the alder catkins as they dangled carelessly in the light breeze.

All three of these early spring bloomers have cylindrical flower clusters with inconspicuous petals, or no petals at all. Each catkin, as they’re called, contains many flowers along a drooping, central stem. All the flowers on any one catkin are either male or female and sometimes there is only one type of flower on a single plant. Botanists call this “dioecious” from the Greek words for two households.

Pussy willows are dioecious, as are the aspens (they are both in the willow family, Salicaceae).

Alders are monoecious (“one household”) and have both male catkins and female cone-like catkins on the same plant.

The advantage to having these long, dangling strings of reproductive structures is that a gentle breeze can easily wend its way through the still-leafless branches and carry a dusting of pollen from the male flowers to the female flowers.

It is the male flower buds of Salix discolor that we think of as pussy willows.  As they mature, long filaments tipped by bright yellow pollen, and connected to nectar glands, extend their welcome to bees and other insects, as well as to the wind.

I paused to admire the subtle beauty of the day. Little droplets of water (or was it ice?) sparkled on the tips of the pearly, pussy-footed buds. The little balls of sleet made intricate patterns of expanding ripples on the dark gray water. And rich colors warmed the bark on the dense thicket of stems.

I have to admire willow for its tenacity. It blooms when there is still snow on the ground, lives where its feet are continuously wet, thrives even in marginal soils, and grows back with renewed vigor after being cut. This means that willows can be coppiced, or cut off so that long, straight, shoots grow anew. The new shoots can be used to weave baskets, or burned for energy.

Willow can also be harvested for medicine. Humans in many cultures had been using it for ages, but in 1763, Reverend Edward Stone (maybe my relation, who knows!), from Chipping Norton in Oxfordshire, made the first scientific study of the effects of powdered willow bark. The bark contains the chemical salicin, which we metabolize into salicylic acid. It is the precursor to acetyl salicylic acid, now known as aspirin.

If you’ve ever taken an uncoated aspirin tablet, you’ll never forget the bitter, astringent flavor that dried out your tongue. Chewing on the tip of a twig from a willow or aspen will give you that same awful flavor. “Who would even do that!?” you might ask. Well, budding botanists wanting an easy way to identify a plant sometimes chew on suspected willow twigs, as do naturalists wanting to surprise students and instill an unforgettable lesson.

On this cold and blustery day, I was tempted wade through the muck and chew on a willow twig myself. It just might help to dull the pain of a slow and dreary spring!

For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI! The current exhibit, “Nature’s Superheroes—Adventures with Adaptations,” opens in May 2014 and will remain open until March 2015.

Find us on the web at to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot,


Fresh sunshine warmed my bare arms and legs as I biked along County Highway D east of Lake Namakagon. The joy of speed, freedom, and my trusty steed brought on an irrepressible smile. As we neared the bridge over a marshy flowage, a cacophony of bird songs began to cut through the whirr of tires on pavement and wind in my helmet. We pulled over onto the shoulder for a better look.

Red-winged blackbirds gurgled and trilled their early spring song that is so energetic it seems to cause ice to melt and streams to flow. A pair of Canada geese honked harshly from their grassy hummock; building their pair bond by shouting together. And then a rattling cry ripped through the air. My head snapped up automatically as I followed the sound and the blur with both my ears and eyes. Finally my focus landed on a slate-blue shape just settling on the branch of a broken snag.

“Kingfisher,” I said out loud, even though we both knew it already, as I whipped binoculars out of my handlebar bag. Just back from Central America, his breast was pure white with a jaunty blue band to match his powder-blue tux. A female would have had a beautiful rusty bar across her belly. Belted kingfishers are one of the few bird species where the females are more colorful than the males.

In the next moment I realized that he had something in his mouth – a large minnow probably – and he was whacking it against the branch over and over with sideways jerks of his head. At some point he decided that it was sufficiently dead. He tipped his head back, gave the fish a little toss, and down the hatch it disappeared!

While this minnow was comfortably bite-size, kingfishers, who are thirteen inches long at most, have been known to eat fish up to seven inches long. Their trick? They leave part of the fish hanging out of their beak until stomach juices digest enough of the fish that it can slide in all the way. Also, the bird’s tiny tongue stays out of the way.

Young kingfishers have such strong stomach acids that they can digest fish and crayfish completely – bones, shells, and all. Once they leave the nest, kingfishers regurgitate pellets filled with the indigestible bits, just like owls.

Those young belted kingfishers, who hatch in May or June, keep their parents busy by consuming their body weight in food each day. Luckily, kingfishers live up to their name with the help of several adaptations. First, they can scope for prey either from a poolside perch or by hovering in one place high above the water.

Like many birds, kingfishers have excellent eyesight. Oil droplets on their cone cells enhance their color vision and reduce glare as they search for prey. Two focal points in their eyes allow them to adjust for the change in refraction between air and water as they dive after a fish. The position of these two foveae gives kingfishers monocular vision in the air (each eye is used separately) and binocular vision underwater (which allows them to judge distance). A third eyelid, called a nictitating membrane, acts like protective goggles.

When a kingfisher dives underwater, its sturdy, conical beak wedges into the water and pushes it aside with minimal impact or splash. Japanese bullet trains, which operate at speeds exceeding 200 miles per hour, and carry more passengers than any other rail line in the world, imitate the aerodynamics of the kingfisher’s beak to reduce noise pollution and improve fuel efficiency.

After grabbing the fish or crayfish with its vise-like bill, the kingfisher flies up to a perch to whack away, just like I witnessed. The young are fed small fish or regurgitated food. As the young grow up, parents teach kids to hunt by dropping fish into the water for the students to retrieve, just like in loon families.

While their hunting adaptations are amazing, the kingfisher’s strangest adaptation is used for digging their nest burrow in a sandy embankment. Their inner two toes are fused together, resulting in what appears be a single flattened toe. This trait, called syndactyly, is not common, but it is shared by kangaroos, wallabies, opossums, koalas, and wombats.

I will never cease to be amazed by the ways that nature has sharpened its every skill and perfected its many tools for survival. As we hop on our bikes (wonderful products of human adaptation and innovation) to continue the ride, an osprey soars overhead, itself a magnificent example of adaptation. Admiringly I glance back toward the kingfisher, and “with a rough and easy cry…he swings back over the bright sea to do the same thing, to do it (as I long to do something, anything) perfectly.” (Mary Oliver, “Kingfisher”)

For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI! The current exhibit, “Nature’s Superheroes—Adventures with Adaptations,” opens in May 2014 and will remain open until March 2015.

Find us on the web at to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot,

Friday, May 9, 2014

Risk and Consequence

Help! Guys, he’s over here. It looks bad! The dull roar of spring runoff rushing down the rapids filled my ears as we rushed over to the yellow whitewater kayak. Our friend Tim sat in the kayak’s cockpit at a funny angle, fully alert, but complaining of back pain and numb feet. “What happened?” someone asked. “The force of the water threw the boat up on shore,” Tim replied with a grimace. Suddenly, everyone was talking at once. “How can we get him out and keep his spine stable?” What if we move the kayak like this?” “Who’s going to grab his weight centers?” “I’ve got his head,” assured Dan, as he took the lead position and began directing the rescue.”

Four people positioned themselves at Tim’s shoulders and hips, others stood nearby, ready to help free his legs and boots from the molded foam foot and thigh braces. I grabbed the bow of the kayak, ready to steady it and then pull it out of the way. “Anyone not ready?” asked Dan. Alert silence. One, two, three, go. With a fairly smooth movement, the rescuers removed Tim from the boat, I pulled it out of the way and went to support his feet. Carefully, we levitated him a few feet up the shore to flat patch of grass.

“Lowering on three,” warned Dan from the head position. “Anyone not ready?” With a slow movement, bending at our knees not our backs, we gently placed our patient on the ground.

“Hey, that was pretty good. Nice job team!” commended Tim while he sat up and brushed off his pants.

Conversation irrupted among the group of Wilderness First Responder (WFR) students as we discussed the details of what worked and what didn’t during our simulation. By now, halfway through the course, we were getting pretty comfortable with the patient assessment system, and responding to (simulated) traumatic injuries, even in awkward places.

All week, this group of 21 students has been learning about risk assessment, emergency care, and wilderness medicine. We’re here for a variety of reasons: some students will be working for Voyageur Outward Bound or other outfitters leading expeditions to the Boundary Waters; others are leading trips for a college outdoor rec program; one woman from Chicago will be leading high school students on service learning trips to Central America. I will be leading kids down the Namekagon River, and adults to the Boundary Waters on public programs for the Cable Natural History Museum.

One thing we all have in common is a passion for adventurous travel, and a need to keep ourselves and others safe while doing it. Could someone really have had a kayak accident like the fake one we just responded to? Absolutely. Would just the possibility of that unfortunate event keep any of us in the class out of the water? It depends.

 “Risk is a function of both probability and consequence,” declares our textbook’s introductory chapter. Therefore, the best way for us to stay safe is to avoid the combination of high probability and high consequence risks. Any sort of outdoor activity requires good risk assessment and risk management skills. By understanding what could go wrong, and how serious different outcomes could be, we are becoming better at both reducing the probability of risk, and reducing the consequences through good patient care.

After this drill, I might scout that rapid one more time before running it. If the water was too high, or I was by myself, or I was in a remote location, I might not run it. That situation has a high probability of huge consequences. After doing simulated CPR on a classmate acting convincingly like she’s just been hit by lightning, I might not watch a thunderstorm roll in on a rocky point. But if someone else takes those risks and gets into trouble, as least I can respond with the basic life support that gives them the best chance for survival.

Wilderness medicine isn’t all about broken bones and serious accidents, though. Much of our class has been about determining if an ailment is serious or not serious, and making sure the minor things stay that way. The best way to cure a blister? Don’t get one in the first place. The best way to deal with infection? Clean even minor wounds well right from the beginning. The best way to prevent injuries from a hasty and risky evacuation? Be able to tell that your patient’s intestinal distress is just a little gas from dinner instead of appendicitis.

In the end, accidents like the ones we simulate in class are pretty rare. I took my first WFR course in 2001, and in the subsequent 13 years, the most I’ve used my knowledge for is blister care and risk management. I’m at more risk for injury while I’m getting to the wilderness in my car than while I’m actually traveling by canoe in the back country.

What if I didn’t go? What if I got scared about the “what ifs” of wilderness travel and stayed home? I think that would create a high probability, high consequence situation, too. The probability is 100% that I would be missing out on life-affirming adventures in beautiful places that bring me deep personal satisfaction. That’s not a risk I’m willing to take.
Once again, Mary Oliver says it well: “Tell me, what else should I have done? Doesn't everything die at last, and too soon? Tell me, what is it you plan to do with your one wild and precious life?”
For over 45 years, the Cable Natural History Museum has served to connect you to the Northwoods. Come visit us in Cable, WI! The current exhibit, “Nature’s Superheroes—Adventures with Adaptations,” opens in May 2014 and will remain open until March 2015.

Find us on the web at to learn more about our exhibits and programs. Discover us on Facebook, or at our blogspot,