Friday, March 22, 2013

Furry Little Monsters (or Squirrels Just Have to Eat!)

The vivid blue sky was starting to fade into a rainbow sherbet of color as the warm spring sun sunk toward the horizon. Crusty snow made for fast and challenging skiing, especially where the afternoon sun had shone strongest, resulting in a glaze of ice in the tracks. It took all of my balance and guts to get down the steep hills safely. Naturally, while out on this ski, I encountered something I thought would make a good story!

On a gentle slope through a stand of spruce, suddenly the skiing wasn’t so fast anymore. Hundreds of little spruce branch-tips littered the ground, and of course, they seemed to congregate right in the ski tracks. Sticking and stumbling down the hill, I cursed the furry monsters that ruined my skiing.

Boy, those furry monsters have been busy! Hemlock branch twigs also littered the ground along the Forest Lodge Nature Trail where I was out snowshoeing, and ski trails all over the area have been sprinkled with green through every spruce and hemlock stand. I guess I can’t really be too mad at the furry mon….er….red squirrels. Spruce and hemlock buds are not their preferred food, but at this time of year, the supply of pine and spruce cones is dwindling, acorns are trapped under crusty snow, and squirrels just have to eat. So eat they do, by nipping off a branch tip, turning it around, nibbling off the bud, and throwing the rest right onto my ski trail.

Red squirrels are highly selective in their foraging behavior, harvesting cones from the tree species with the highest seed energy per cone first and systematically working their way through species of conifers by energy density per cone. As spring progresses and hunger gnaws, squirrels will also dine on poplar buds and catkins, elm buds, and maple buds. They will even drink a little sap from the maples once they have opened a wound. Mushrooms are another favorite food.

As the days lengthen, red squirrels also begin to think amorous thoughts, and you may notice evidence of their scramble competition mating system. Males typically invade the territory of females in estrus and pursue them in obvious mate chases. During mate chasing, a single dominant male actively pursues a female and drives off other subordinate males using calls or direct chase. Timing is important, since she will only be receptive for a single afternoon. Keep your eyes and ears open for signs of this wild scramble in the woods.

Nesting sites are located within 30 meters of a cone cache. Red squirrels are highly territorial, with their food cache, called a midden, as the center of focus. Caches help female squirrels assess the resources available for reproduction and weather years of low cone production. You have probably noticed a red squirrel vocally defending its territory with its full repertoire of rattles, screeches, growls, buzzes and chirps. Because red squirrels often cache all their food in a single midden, they must defend it more fiercely than gray squirrels, who have many smaller, dispersed food caches.

As you might imagine, not every cone in the cache will be eaten. Red squirrels use their great sense of smell to locate buried middens--even under four meters of snow! But the death of the owner or other circumstances can lead to middens being abandoned.  When this happens, some of the seeds are left to germinate.

Planting seeds is not the only service a squirrel provides to the forest. Fungi that help young trees acquire nutrients and grow are spread through caching as well. In addition, as squirrels nibble off the buds of conifers, this can cause the trees to grow multiple tops. While this is bad for the tree and timber value, it provides nest sites for a variety of birds and mammals and keeps forest diversity high.

So, while I might curse those furry monsters for slowing down my skis, I can still appreciate that they are an important part of the forests I enjoy so much.

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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