One of my favorite activities in winter is to go out looking for animal tracks in the snow. In early-mid November this year, the snow was perfect — not a lot of it, but soft enough to register animal passage and firm enough to hold the tracks’ shapes.
So, off to Eaglecrest I went, with two good friends who like these little explorations too. We found lots to look at. Porcupines had plodded in and out among the trees, in some cases making small highways of repeated use. A few red squirrels had ventured out of their burrows. A weasel had covered a lot of ground, bounding with shorter leaps when it went uphill. It investigated many a fallen log and stump in hopes of a nice lunch. Weasels have to eat a lot, just to keep warm and feed their active metabolism.
Voles (or maybe mice – it’s often hard to tell which) had run over the snow from one grass tussock to another or from log to bush and back again. These were the most common tracks, often right out in the open meadows, where they might be easy marks for predators. But we saw no signs of lethal events.
Near the road, we found a spot where one indisputable mouse had hopped across. On either side of its trackway were marks of a tail flick. It couldn’t have been a vole, whose tails are very short, so it had to be a mouse. Why it had flipped its tail from side to side was not clear, however; we speculated that perhaps it was slightly off balance on the coarse cobbles at the edge of the road and used its tail to restore an even keel.
We found a few lines of tiny tracks that were made by shrews. Emerging from one dime-sized hole, crossing over the snow to an equally minuscule hole, occasionally they tunneled just barely below the snow surface.
Every so often, we looked up instead of down and noted that quite a few trees had long-dead tops. No mystery there, given the howling gales that sometimes whip through this area. But none of the lower, lateral branches had grown upward to replace the missing tops. We’ve all seen conifers whose original “leader” at the top of the tree has been killed but a lateral branch just below it has taken over as leader, creating a kink in the trunk. We puzzled over why this hadn’t happened on the trees in which the entire top was dead.
An answer might lie in the way that hormones control growth. Normally, the leader at the top of a conifer suppresses the growth of lower branches; this is known as apical dominance. But the effects of apical dominance diminish as the distance from the leader increases. So, perhaps, when the entire top of a tree is killed, the distance from the leader was so great that there was no dominance exerted on the remaining branches. Thus, the lower branches had not been suppressed and they did not respond to the loss of the tree top.
A few days later I walked out into the Mendenhall Glacier Recreation Area near Crystal Lake. Tracking was still good and there had been lots of activity. A porcupine had trundled across the ice on the lake, and a weasel (I think) had walked (not bounded) along the footpath. Squirrels and snowshoe hares had crossed the path.
The most interesting marks were made by a bird, whose wingspan exceeded five feet—surely an eagle. Its wing tips brushed the snow in several places around a patch where the snow had been disturbed. Here I could see some heavy-duty bird tracks, confirming the presences of an eagle. All around this area were raven tracks too. But there was no clue about what the eagle was after—unless it might have been a raven (eagles do capture ravens sometimes). It seemed unusual for an eagle to be hunting in a wooded area where the only open ground, where an eagle could spread its wings, was the path itself.
Lots of stories in the snow, so winter was off to a good start for me!
• Mary F. Willson is a retired professor of ecology.