By Boak Wiesner
The end of winter’s days brings about a certain sadness in me – yes, it’s true! Maybe because I have been out in it for so many years now involved a wide variety of activities. Minnesota doesn’t see some bird species down from the north unless the winter’s severe. Maybe it’s the full moon that does it to me. As Robert Service relates: “The stillness, the moonlight, the mystery. I’ve bade ‘em goodbye, but I can’t.”
With the end of winter also comes the end of that stillness. As the hectic days of courtship among the animals and plants around here gets underway, there are more and more sounds out there, increasing geometrically it seems from the vernal equinox to our summer solstice. The muffling effect of the snowpack will be gone and with it the utter silence of a winter’s night.
Skeins of geese honking overhead greet me as I wandered into the ravine to look up my old friend the “holey” squirrel from last year – no one home! But instead I chanced to see a little red squirrel lapping up some maple sap from the end of a broken branch. Not the one that I was looking for but it got me thinking about the diversity of life. Like, why are there so many kinds of squirrels in our state but just a few species of chickadees? Does that make squirrels “better” or just luckier? I was once called on to settle a bet between two friends about squirrels – one contending was that the fox squirrel was the same as the red. Which, they’re not. I corrected him and went on about the ten different kinds of squirrels in Minnesota, most of which live underground!
So then, why are there so many kinds of living things? But at the same time, why are there “only” so many different kind of things in a given habitat at any given time. (I’m watching two of our most common woodpeckers side-by-side, the downy and the hairy, two versions of a common theme.) Red oaks stand next to white with the bur oak out in the prairie areas. From whence comes this diversity? The hardwood forest around here supports lots of kinds of trees and diversity is a measure of the health of a forest. Essentially none of the forests around here are all that “natural” as those who came before us burned the areas here at the edge of the prairie in an effort to keep elk around. It what allowed the red oak acorns to get a foothold and grow to the big trees here at the Arboretum, in the ensuing open areas.
I’ll leave you with this much more concrete example of the way things work. Half a millenium ago, Da Vinci noted that the branching of trees follows a mathematical relationship: that the cross-sectional area of the wood is the same at any level in the tree. Research indicates this keeps trees from getting blown over by the wind!
Boak Wiesner is a Minnesota Naturalist volunteer.