January 27, 2019: The Colors of Ice

This week included a trip up to Arbutus Hill Pond to see what winter there has to offer.  It was after the snow and before the January Thaw, so the skiing was good and the views were beautiful.

The winter scene at Arbutus Hill Pond

Breaking out fresh snow heading up the Magenta Trail

The pond sure looks a lot different in winter than in the summer, and it offers a chance to get up close to some of the nesting sites that are not accessible in summer (nor would it be wise to disturb the residents anyway).  In addition to getting a good look at the beaver lodges, I was able to check out the heron nesting trees.

Heron nest atop a tall pine killed when beavers dammed up the pond

The nest seemed smaller than I remember from the summer - I wonder if it lost some mass during the recent storms, or whether is just looks larger from a distance.

On the way up I came upon a set of tracks running right along the trail that included an unusual mark in the snow that I couldn't figure out.

The mystery mark

It looks like some kind of studded wheel was rolled along beside the track.

This fisher was content to travel a long ways on the trail

I decided the tracks were from a fisher based on their size and track pattern.

A scent marker in a conspicuous location

At one point it also marked a log on the ground, which fisher will do.

Fox and coyote do this as well, but the tracks do not match up with a canine;  they have the all the characteristics of a member of the weasel family (which includes the fisher).

A perfect example of a fisher track set

One clue is that the mystery mark is right at the only place on the long trail where the fisher broke through the crust.  Is it possible that the hunter was carrying a porcupine and when it broke through the snow, its dinner hit the surface and the quills poked all those tiny holes in the crust?  Fisher will kill porcupine, and this trail was leading away from prime porcupine habitat, so it's a possibility.  Also fisher don't usually travel in a straight line;  they tend to weave all around in the forest, searching out rotten trees and tall oaks for squirrel nests.  So that lends credence to the thought that it had already caught its prey and was carrying it straight back to its den.  I haven't come up with a better theory - any ideas out there?

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New Hampshire Public Radio has an outdoor/nature piece every other Friday called "Ask Sam" in which Sam Evans-Brown always has something new and interesing to present.  This week the topic was the color of ice (Why is Some Ice Black and Some Ice White?) and I learned several things I didn't know before.  Right off the bat he corrected a misconception I had that water is colorless.  He explained that water is actually blue - a very faint blue - which is why it usually appears colorless to our eyes.  Only when water is very deep are our eyes able to detect the blue color.

Now what about the black ice we had earlier this winter?

This ice formed on a very cold, calm night back in December

He explained that ice appears black when it freezes under calm enough conditions to form very large crystals, which present few facets from which light can reflect and refract - thus light passes through it, and it appears black.  On the other hand, if water is disturbed when it freezes - for example, churned up by waves or wind, the crystals are banged around, preventing them from growing large, which results in countless tiny ice crystals, each with many surfaces to reflect the incoming light (white light) back to our eyes.

White ice near shore

He also describes the interesting aspects of how glacier ice is formed, and how its own weight squeezes out impurities resulting in extremely pure ice.  You can read or listen to this story as well as previous reports here.  And don't forget, next weekend is Pond Hockey on Meredith Bay.  If you look around, you might find your own little glacier on your local lake.