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Cratering Caribou Keep Cool

Posted By: Martha     All Posts by Martha  

January 14, 2013


While skiing, snowshoeing, and dog mushing in Denali National Park, caribou tracks often crisscross our human paths. Every now and again the caribou tracks are interrupted by a hole dug to the ground with the snow flung nearby.  These holes can be 2-12 inches deep and 1-6 feet in diameter.  Woe to the fast moving human snow traveler who encounters a large “crater” in their path.

Caribou dig through snow to find food, a process that leaves behind craters of various sizes and to the human observer in seemingly random locations, including on well-packed ski and dog mushing trails. The name caribou comes, through French, from Mi’kmaq qalipu, meaning, "snow shoveler". The caribou in Denali National Park are recognized as Rangifer tarandus by modern day scientists.

The Mi’kmaq, First Nations people of the Canadian Maritime Provinces, watched caribou move large quantities of snow. They shovel the snow with their hooves usually to ground level to find lichens, dried willow and birch leaves, sedges, grasses and lingonberries. In the winter up to 70% of their diet can be lichens but not just any old lichen will do; mostly they feed on a particular genus of lichen often referred to as reindeer moss, Cladonia sp. In areas of shallow or patchy snow, it may take only a few minutes to expose enough food for the day. On the other hand, cratering may occur for more than two hours each day as caribou labor to break ice crusts or move heavy, deep snow. They are using their nose to smell the correct lichens and thus choose a place to crater.

The caribou nose was recently discovered to have a remarkable role, not in olfaction, but in thermoregulation. Caribou have specialized noses featuring nasal turbinate bones (shaped like a spinning top) that dramatically increase the surface area within the nostrils. Incoming cold air is forced over the extensive mucosa covering the turbinates and thus warmed by the animal's body heat before entering the lungs, and water is condensed from the expired air and captured before the breath is exhaled. Thus the nose helps keep caribou warm and hydrated. The newly discovered role is that the same increased surface area is used to keep caribou cool. When running from a predator or in hot weather caribou need to dissipate heat. The first defense is to pant but when the brain temperature is about to go over 102 degrees F, the blood to the brain is re-routed over those turbinate bones. The increased surface area allows the hot blood to cool before it causes brain damage. *

The amazing caribou uses its nose to stay warm during frigid winter days while creating craters for unwary snow travelers to stumble over. And it uses its nose to stay cool in the summer when fleeing from a wolf. Of course, Rudolf, that legendary reindeer used his nose for an entirely different purpose.

*Knight, Kathryn, Rudolph’s Cooling Strategy Revealed, J Exp Biol 2011 214:i.  doi: 10.1242/jeb.066621

Thanks to Matthew Iverson for the sketch.

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A Week in the Life

Posted By: Martha     All Posts by Martha  

March 04, 2010

This past week has been busier than usual but is emblematic of the activities this Camp Denali year-round staff member partakes in during the dark, cold winter months.

My name is Martha McPheeters. I am a Naturalist Guide in the summer and the Personnel Coordinator in the fall, winter and spring. Right now it is hiring season. My work life is full of interviewing potential staff, setting up in-person interviews, checking references, revising last years hiring documents and deciding who will work at Camp Denali/North Face Lodge during the upcoming summer.  The rest of this blog is about my non-work hours.

First to set the scene, it is NOT dark or cold by interior Alaska standards as this February week unfolds.  The most recent snowfall and sub-zero temperatures were in January and it is now late February. The minutes of sunlight each day have been increasing steadily since the winter solstice so that now we have nearly 11 hours of sun-above-the-horizon time each day.  At Solstice we had 4 hours of sun-above-the hypothetical-sea-level-horizon time. The light comes rushing back at 4-7 minutes per day. From the beginning of this week to the end, the amount sun-above-the-horizon time has increased by nearly 49 minutes.

Friday: On certain Fridays after work I join the Women’s Ice Hockey Team in Healy, AK to scrimmage. Today is the tenth day of above 32-degree temperatures and the outdoor rink is a big puddle. Hockey practice is cancelled so I head home.

Saturday: The DERT bags (the newly organized Denali Emergency Response Team) execute a practice search and rescue. Sixteen of us show up at 10 AM and pretend to find four skiers buried in an avalanche at some distance from our meeting point. With the rescue complete, the DERT retreats to 229 Parks Restaurant and Tavern to debrief the experience.  Many participants suggest improvements for next time.... the real rescue we hope will never happen.

Sunday: Sunday begins with brunch at my cabin. We eat artichokes that a California friend mailed to me after listening to me complain about the scarcity of the vegetables in the interior of Alaska in the winter. Brunch is followed by a ski trip up Riley Creek in Denali National Park on no-wax skis. My preference is waxable skis but today the snow underfoot has been thawed and refrozen maybe 10 times making proper wax selection impossible.

In the evening, I put my books and homework into a pack and walk over to a neighbor’s house for Physics Class.  This small group of older women who had Math or Physics majors in college have been getting together weekly to take an online Physics course from MIT. Actually that was last winter, this winter we have become less formal and choose topics of mutual interest to research. Tonight we are making telescopes from cardboard toilet paper tubes and lenses we acquired from broken cameras, broken magnifying glasses and toys. We find ourselves flummoxed by the need for a parabolic mirror. In the process we discover that collectively we do remember the equation for a parabola and how to calculate the focal length of the mirror we do not have.

Monday: It is still above freezing so I go for a bike ride to Carlo Creek on completely bare roads. Then I move firewood from a tarp-covered heap to my now half-empty woodshed.  I wonder if wood-burning season is half-over.

Tuesday: Today is cooler, a high of 20 degrees and we’ve had a whiff of snow greatly improving the ski conditions. I go for a six-mile ski on my waxable skis.

Wednesday: Now there is an inch of new snow and the temperature is 10 degrees. I hook up a neighbor’s dog and skijor for nearly three hours covering more miles than I could ski in the same period of time. (Skijor means to use a dog to assist a cross-country skier. The dog and the skier wear harnesses and are connected by a length of rope.  The skier provides propulsion with skis and poles while the dog pulls.)

Trudging home in the evening, the snow has the unmistakable and satisfying squeak that accompanies sub-zero temperatures. I get home and sure enough, it is 4 below zero.

Thursday: I attend my weekly Tai Chi group in Healy. This group learned a Yang style short form in 1999 and has been meeting weekly ever since to read from the Tao Te Ching, do Shibashi and practice the form.

Friday: Three more inches of snow have fallen. Yippee! A friend asked if I would be willing to exercise her sled dogs while she is gone. This friend, Nan Eagleson, former Camp Denali guide, is going to “town” to guide Exploritas (formally Elderhostel) trips to the Fur Rondy and the Iditarod dog sled races. I love mushing dogs and this afternoon I hook up Nan’s six mellow, aging sled dogs and go for a run. There is nothing quite so thrilling or quite so Alaskan as riding the runners behind eagerly pulling dogs.

In the evening there is a dessert potluck to kick-off Winterfest. (I did find time to make cookies.) Winterfest is a three-day celebration of winter for those of us living just outside the eastern boundary of Denali National Park.  The keynote address this year is given by our very own Jerryne and Wally Cole, the owners of Camp Denali. They give a wonderful presentation that starts with baby pictures of Celia Hunter and Ginny Hill, the founders of Camp Denali, and end with baby pictures of their grandchildren, the potential inheritors of Camp Denali.

Closing: Perhaps these few paragraphs will give the summer guest to Camp Denali pause to re-consider the inevitable question that year-round staff answer repeatedly, “What do you do all winter in Alaska?”

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Darkness and Light in Denali

Posted By: Martha     All Posts by Martha  

July 17, 2009

    Living at latitude 63° north, we observe wide swings in the amount of light and dark in the days; more darkness in the winter, more light in the summer. Denali National Park is south of the Arctic Circle, which is at 66.7° north, so technically the sun rises and sets—i.e. goes above and below the horizon—each and every day in our part of Alaska. However, because we live in the mountains, the ridges and ranges surrounding us often obscure when and where the sun rises and sets.
    At the winter solstice, the sun is technically above the southern horizon for a mere two hours, creating four hours of visible light. At the summer solstice the sun dips below the northern horizon for two hours, creating twenty-four hours of visible light. The effect of these extremes on my mood or circadian rhythms is slight. We are either gaining or losing mere seconds of light each day. Neither extreme changes my work schedule or indoor activities. During the months before and after the solstices I either awake in the dark and go to sleep in the dark, or I awake in the light and go to sleep in the light. There is a pleasant sense of stability in this pattern. My life feels calm and balanced.
    Since I do not suffer form seasonal affective disorder, the 20 hours of darkness has little effect on my emotions. I find myself happily skiing, skijoring, and mushing with a headlamp on my head and an extra one in my pack. The darkness, the stars, or upon occasion the northern lights are all welcome visitors to my outdoor pursuits. Also, I find the cold, dark times very conducive to introspection, which my busy summer life precludes.
    The balance and calm I experience around the solstices is upset during the months around the equinoxes, vernal in March and autumnal in September. At these times we are gaining or losing up to seven minutes of daylight each day! This means that on Monday I can awaken with sunrise at 6:30 am, but on the following Monday, a mere week later, I awaken at the same 6:30 time in almost full daylight or almost full darkness. Losing seven minutes a day for seven days—that’s a change of 49 minutes in one week.  My body and circadian rhythms get all out of whack, and neither stability nor calm seep into my cells during months before and after the equinoxes.
    Contrary to what many of my Lower 48 acquaintances may think, the darkest month is not the most difficult time of year. For me, the most grating times are those twice yearly periods of rapid change, when it seems all the world is in flux and no new day is like the previous.

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Denali Dispatch

It is our pleasure to present Dispatches, a journal of the goings on at Camp Denali & North Face Lodge. Written by members of our staff, Dispatches is an opportunity to peek into the special sightings notebook, brush up on Denali National Park issues, read about our ongoing projects in sustainability, and maybe get a whiff of what’s cooking in the kitchens. Dispatches will carry on through the winter, when we hope to share stories of snowy ski adventures, deep cold, and the events of a small Alaskan community.