Tuesday, January 8, 2013

Big Furry Snowshoes


Skis swished and our breath came out in puffs of white as we traveled through a majestic corridor of snow-laden fir trees. We looked up to a bright blue sky, but on either side of the trail the young evergreens grew tightly packed together, each striving for just a little more sun. Thinner snow under the trees recorded the comings and goings of snowshoe hares.


As the firs gave way to a mixed coniferous/deciduous forest at the trail intersection, small maple and dogwood saplings dominated the understory. The shortest of the shrubs were trimmed to stunted twigs with sharp-angled tips. These little bonsai trees are a result of hares browsing vegetation with sharp, ever-growing incisors, similar to beavers. In contrast, nibbled-on twigs a meter high bore tips shredded by the coarse lower teeth of deer.


Snowshoe hares are well adapted to harsh, snowy winters. Their huge hind feet help them float on top of the snow, and their seasonally white fur lets them blend in.  The hare’s pineal gland (which even in humans produces melatonin, a hormone that affects the modulation of wake/sleep patterns and seasonal functions) senses changing photoperiods in the fall and spring, and triggers the color transition between brown in summer and white in winter. It takes about ten weeks for the change to be complete, and if the hare is not on schedule with the weather, it may stick out like a sore thumb.


So, like us skiers, hares may not fare so well in our warming and less-snowy future. Scientists at the University of Montana are studying the hare’s predicament, and asking questions like: “Will hares continue to shift coat colors on cue, regardless of the presence or absence of snow? Will this drive them to extinction? Or will they be able to adjust their seasonal pattern in time to fit new conditions?” There is evidence that they can adapt varying snow amounts -- not all snowshoe hares change color – some in the far north stay white, and some in Oregon and Washington stay brown.


“Hares are important because they are prey for almost everything in the forest that eats meat,” researcher Scott Mills said. “Without hares, the ecosystem unravels.”


One predator who is particularly dependent on snowshoe hares is the Canada lynx. With its own set of huge, furry snowshoe paws, extra-long legs, and warm fur, the lynx can out-compete other mid-sized predators in areas with deep snow. And I do mean deep. Lynx thrive with an average annual snowfall of almost nine feet.


Fur trapping records going back hundreds of years show that the lynx numbers rise and fall on a cycle of ten years, two years behind the snowshoe hare population cycle. At least they did. The lynx population in Minnesota stopped following the hare cycle closely in the 1980’s.


Lynx have never been common in Wisconsin, but since 1900, lynx sightings in our state have occurred when the 10-year cycle of snowshoe hares in Canada has crashed. (When this happens, the animals have to wander farther to find food.) But a lynx hasn’t been spotted in Wisconsin since 1992.


With less snow on the ground, lynx lose their advantage. It becomes harder to compete with other mid-sized predators like pine martins, fishers, and coyotes. The lynx’s own cousin, the bobcat, is its fiercest competitor. These days, where you find bobcats, you just do not find lynx.


It is hard to imagine that the world is warming when your chin feels like it might freeze off, and your fingers and toes are numb. I tried to ski faster to warm up, but uneven bumps in the trail, shallow tracks, and a few thin rocky places made it hard. With only ten inches of snow in the woods, the North Shore of Minnesota was just barely skiable on New Year’s Eve.


Still, a slower pace made it easier to check for animal tracks along the trail. I co-taught a biology class that tracked wolves and lynx up here during the winters of 2005-2008, and I just can’t break the habit of tracking as I ski. One of our students found a lynx track near here in 2008, and we shared our data with the Natural Resources Research Institute in Duluth, which has radio collared over 33 lynx since 2003.


On this day, we found a perfect print where a wolf had crossed the freshly groomed snow. I slowed a bit to peer over my shoulder at another animal trail, but thought it was just a deer. Then my fellow skiers stopped too, and pointed out four tiny toes in a lopsided C shape, and a three lobed heel pad. No claw marks tipped the toes, and no fur obscured the details in the shallow snow. The whole track was just an inch and half wide. Bobcat.


Skiers, snowshoe hares, lynx. We all LOVE winter. During Birkie week, the Museum is creating an exhibit called “We LOVE Winter,” that will highlight the fascinating winter adaptations of animals. Come visit, learn more about critters who share your love for winter, and gain a new appreciation for this challenging and delightful season.

For over 44 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 13470 County Highway M. The new exhibit, STAR POWER: Energy from the Sun, opened in May 2012 and will remain open until April, 2013.


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/.

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