Monday, January 21, 2013

Moose Tracks and Trends

A few inches of crusty snow reflect the sunshine brightly, and the sounds of dripping icicles fill the air. A stiff breeze tousles my hair, but even that is not enough for me to put on a hat. Thirty-one years ago today, my birthday, a blizzard howled through the Midwest, and my parents were lucky that a short break in the storm allowed them to get safely to the hospital. Today, in only a sweater and jeans, I am overheating like crazy. Mittens dangle in my hands, and my windbreaker flaps around my waist.


This warm spell triggers a little daydream about canoe season. My mind drifts back to a calm August morning near Long Island Lake in the Boundary Waters. It was the first portage of the morning, and as we slid up on the smooth sand, we noticed that someone else had been there first. Someone with six-inch long toes, two per foot, shaped like a mirrored pair of commas.


Thinking of the large, gangly moose that made those tracks takes me back to a very different adventure in the Green Mountains of Vermont. I was snowshoeing up through a drifted alpine glade with some classmates, and we came upon a moose trail. The moose’s feet had punched huge round holes in the snow’s crust, which destabilized it. The fractured crust could no longer hold us on top either, and we sank through up to our hips.


The depth of the snow did not seem problematic to the moose. Moose’s bellies are about 35 inches off the ground, twice as high as a deer’s, and just about up to my waist. In addition to having a height advantage, moose can lift their front feet nearly shoulder high, enabling them to travel easily over fallen trees and through deep snow. Hollow insulating hair and a huge body mass (1,000 pounds easily), combine to make them well adapted to cold, snowy winters.


We clumsily followed the tracks for a little bit, and in one shrubby opening I noticed a strange pattern. The moose’s footprints went on either side of a 10-15 foot-tall mountain maple. Why was the moose straddling a tree? I grabbed as high up as I could and bent the top of the flexible sapling down to eye-level. Sure enough, the tips were torn off raggedly, a result of the moose’s lack of upper incisors. The huge herbivore was walking over shrubs, bending them underneath its huge belly, and then munching on the most tender buds.


Have you seen a moose in Wisconsin lately? Probably not. You’re lucky if you have, since only about 20-40 remained in the state as of 2003. Historically, moose were common in the northern third of Wisconsin. Hunting, habitat change, and competition from deer caused their extirpation in the early 1900s. Moose from Michigan and Minnesota have since wandered back into our state, but have not established a significant population. The two primary reasons, according to biologists, are a lack of habitat and relatively high deer numbers. Deer carry brainworm, a parasite that can be tolerated by deer, but that kills many moose.


It is days like today that make it harder for moose to live here or in neighboring states. In winter, moose tend to exhibit heat stress at 20 degrees Fahrenheit. When the entire winter is warmer, moose are stressed all season. Higher temperatures in the summer are no better.


Add this to the fact that the moose’s pests like mild winters, and you have a problem. Biologists are now documenting individual adult moose infested with from 50,000 to 70,000 ticks, a ten- to twentyfold increase over what used to be a normal load. The stressors were too great for the moose population in northwestern Minnesota, which plummeted from 4,000 animals in the 1980’s, to less than 100 just a few years ago. In northeastern Minnesota the population has been halved in just six years, dropping from 8,840 animals in 2006 to just 4,230 in 2012.


"A variety of factors may be contributing to the decline, but ultimately I think the real driving force is the climate," says Dennis Murray, main author of the northwestern Minnesota moose study. "The climate change is tipping the balance."


As I hoof it back up the hill toward home, I can empathize with the moose. Thirty-one is a fine age, but a terrible temperature for January. What little skiable snow we had is melting, my expensive winter gear is languishing in a closet, and all sorts of insect pests are surviving cozily in their warm hibernacula, just waiting for spring. At this rate, they will not have to wait long. Sobering thoughts for a warm, sunny, birthday walk.


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 current exhibit, STAR POWER: Energy from the Sun, opened in May 2012 and will remain open until April, 2013.


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