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On the Trails: Puzzles near Peterson Creek

Posted: March 28, 2014 - 12:01am
Mouse feet and raven wings left tracks in the snow near Peterson Creek.   Photo by Kathy Hocker
Photo by Kathy Hocker
Mouse feet and raven wings left tracks in the snow near Peterson Creek.

The lower reaches of the present-day Peterson Creek near Amalga Harbor were under salt water for thousands of years. Two or three hundred years ago, as the Little Ice Age waned, however, post-glacial isostatic rebound gradually raised the land, forming the level meadows, now dotted with spruces and alders, that reach from the present shoreline to the Peterson Lake trailhead. Peterson Creek wends its way down from the lake, through rocky canyons, and then cuts a route through the sediments of the flat meadows to a salt chuck and the sea.

One day in early March, instead of taking the trail, I headed out into meadow adjacent to the parking lot, just to see what I could see. It was snowing, so any animal tracks had been obliterated. I soon noticed that most of the numerous elderberry bushes had been mutilated by some critter that removed the youngest twigs or, occasionally, neatly gnawed off their bark. Some of these bushes stood erect, over eight feet tall.

Who was the perpetrator? The most likely twig and bark eaters were porcupines, which are known to browse elderberry branches. And I’ve seen several porcupine lairs under large trees on the nearby ridge. But how to account for the missing twigs ten feet above the snow line? Barring the unlikely prospect of a giant porcupine (left over from the days of Beringia), there seem to be two possibilities. One might be that the foraging porkies climbed up to the top of these shrubs. But porcupines commonly weight fifteen to twenty pounds, sometimes even more, and elderberry branches are both small and rather brittle. So I have a hard time imagining even a half-grown young one up in the skinny tops of these shrubs.

OK, so perhaps these tall stems had been bowed down by earlier, heavy snows, as lots of the alders still are, but somehow they have now sprung free and resumed the erect form. This too is somewhat difficult to imagine—bending a tall elderberry trunk down to snow level without breaking would seem to be no mean feat. One outstanding example was a tall trunk at the edge of a gully: to account by this idea for the browsing at the tip-top, the trunk would have had to be bent so that its top was lower than its base. It’s a puzzlement!

The fringes of this meadow are characterized by lots of alders, many of them of good size. Some years ago, a friend took a group of us here, so we could see that the majority of the alder trunks were scarred by bear claws, sometimes up to twenty feet high. On my current ramble, I didn’t see any scars that looked relatively new; some were nicely healed-over and others were mostly so. Why so many scarred trees? One idea is that mama bears parked their cubs there while they went fishing in the nearby creek. But not recently, it seems, because I could find no scars that looked even moderately new. Do today’s bears just have different behaviors than their predecessors? Has something changed in the neighborhood to make this site less popular?

There were signs that smaller creatures were active under the deep snow. In a stand of salmonberries, there were several small, deep holes at the bases of the canes. These were not made merely by wind wagging the canes back and forth, but rather by mice or voles that surfaced occasionally. The holes were also big enough for a weasel to access the runways beneath the snow.

Remember those two sunny, cold weeks in late February and early March? On one of those days, with two friends, I plodded across that first meadow, over a small ridge, to the creek. We slowly ambled upstream on the thick ice. The creek had seen big seasonal changes earlier in the winter. A heavy layer of ice had formed, over a foot thick in some places, but a prolonged warm spell had brought down a lot of high water. The old ice was torn up, chunked, and tossed around, adding new scars onto old scars on trees at the creek’s edge. The ice chunks themselves varied in structure, some neatly layered, like slate, and others clear with enclosed air bubbles, and so on. Many of those chunks had been reassembled into large creek-side berms of consolidated blocks; we called these re-frozen piles “ice conglomerate’ (by analogy with structurally similar rock formations).

The new ice was solid and stable, great for walking, but until recently there had been some short stretches of open water, now filmed over with very newly formed ice. Before the last deep freeze, mink and mice had run from bank to water’s edge and back, many times. Along the side of one previously open stretch, some animal had walked around and left scuffled patches in the snow. Lots of activity of some sort, but no clear clues indicating what had happened. Judging from a few indistinct footprints and some wing marks, we thought that ravens had been here. But doing what?

At another newly iced-over reach, an eagle left marks of its massive toes and long wings. Perhaps it was bathing? Or just being hopeful of lunch?

More questions than answers!

• Mary F. Willson is a retired professor of ecology.

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