Tuesday, December 17, 2013

Ice Prints

We had a cold November and are having a colder December, but the average high temperature, which for both months is over freezing, will have its days. Because of those highs walking on the ice was iffy, if not slushy, until in mid-December when we had a string of nights around 0F and days in the teens.

Animals are not so circumspect and when they walk on the wet ice as it is freezing, they make an impressions that can last long after their cold wet walk atop puddle, pond, or river.

There is no better way for a beaver to remind us that along with an amazing tail, it has impressive hind feet. A few clicks on some photo editing buttons can make a beaver’s ice prints worthy of being encased in a museum.

Viewed in isolation one could spend hours calculating the size and intentions of the monster who left those prints. Look over the dam it was walking to and you see the water it dived into as it swam under water and under ice for home.

If humans had such flippers for feet more of us would be swimming under the ice from hole to hole.

When I see otter tracks in the ice my reaction is more visceral, though it's hard to describe what I'm feeling let alone what the otter was feeling. The first prints I saw in the ice at the edge of the Deep Pond showed an animal definitely not testing the waters. 

It wasn't walking, nor trotting, it was springing onto the pond, picking up speed

for a slide

It looked like the otter was heading for a little hole behind the dam. I walked around the pond (not walking on the ice just yet) and saw that the otter made a hole in the ice along the opposite shore of the pond, and danced on the ice there.

In the snow on the nearby shore was a generous piles of scats.

Easy to see that the otter got plenty to eat in the pond. Since the tracks in the ice are distinct and deep and the tracks around the hole in the ice indistinct and shallow, the air temperature likely dropped while the otter foraged under the pond.

I see the boldest displays of otter ice tracks on South Bay. In the section of the St. Lawrence River where I live on Wellesley Island the whole river from the Rock Island Lighthouse west to Lake Ontario and beyond
is usually frozen over by February. Because the current picks up at the lighthouse the main channel along much of the south shore of Wellesley Island stays open. 

The process of freezing begins in the bays. Beginning in late November and often continuing through December and the first half of January the ice front moves up and down South Bay depending on wind and warmth.

Otters commonly fish along and under that yo-yoing front of ice. Here is a photo from January 7, 2005, showing the tracks in the snow at the otters’ latrine at the entrance to South Bay.

I have never seen the otters fish there, but I can see their slides along the edge of the ice, clearly marking where they come out of and go back into the river.

Of course, otters navigate the ice when it is covered with snow as this photo from January 6, 2011, shows. Fresh snow on ice can create a slushy interface which can leave a nice frozen slide.

Otters have complete command of the water and the fish they want to eat are under water so my obsession with otters slides and prints on the ice looks at the  otter’s problem from the wrong side of the ice. Once on the ice of the bay heading for open water the drama of the chase is usually over for the otter. It demonstrates its genius for survival under the ice.

Otters know things about the freezing point of water that we will never fathom. During cold calm nights vast expanses of the river can freeze seemingly into one sheet of ice. On January 22, 2006, I saw an abstraction sketched on the ice or was it under the ice or through the ice or perhaps the otter or otters that made the impressions were oblivious to the nearly instant formation of ice all around it as it bore down on a fish?

The photos I’ve shared so far might give the impression that an otter faces winter out on the river alone. Some do but most don’t. On December 15, 2004, thanks to a layer of snowy frost on the ice, a group of otters showed that running and sliding on top of the ice, where there are no fish to be caught, is sometimes more than a matter of getting from one place to another.

My guess back then was that a family, a mother otter leading two pups, was up on the ice. One might suggest that they were playing but young otters have a very short time to be schooled for winter survival. The mother had to show them how to manage the ice which only got thicker in the coming days.

On January 13, 2005, the temperature hit 50F, softening the snow on the ice. On the 14th I saw slides all over the ice but it was too slushy to walk on the ice and examine them. Then the cold returned and I could walk out on the ice and get close to the slides. At first glance the photo below seems to show one otter coming out from a hole along the shore and running toward the middle of the bay.

But there are small prints next to big ones and a bit farther along the trail, the pup's prints separate from its mother’s.

Of course the pup did not make as great an impression but y
ou can almost gauge how much bigger the mother's tail is.

The pup did get in stride and hit speed enough to impress a perfect set of prints in the slush that soon froze solid.

While adult otters do stay in the river all winter even as ice covers all but a few areas of open water, mothers and their pups usually return to the beaver ponds where she reared her pups in the summer. On February 11, 2001, I saw the frozen slides of a mother and her three pups behind the dam of the Second Swamp Pond.

It's in those ponds that I have gotten some videos of how expertly otters manage to survive when water freezes.

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