Sunday, January 13, 2013

Beavers Under the Ice

Secret Pond is mostly iced over
For the last several weeks our beavers have been living in their lodge and for the most part, remaining under the pond's ice cover. I cut a hole in the ice near the shore and there I've been leaving some assorted branches and apple pieces. Lately, a few of the beavers, including Julia, the adult female, have been seen coming up through the hole. Most of the others have not been seen, which is probably a good sign and an indication that the beavers winter food reserves remain in good shape.
Julia emerges to take an apple piece
The beavers have not been venturing out over the deep snow, which is understandable. Even though they have large feet, which seem like great natural snowshoes, the beavers' bulk makes them especially awkward when traveling in snow. However, when necessary they will brave it and venture out to cut and retrieve trees.
A beaver wrangles a large branch into the pond
One day last week, a gap in the ice opened up on the other side of the pond –right over the original stream channel. I didn't notice any activity around it, until I heard a branch splash into the water. Evidently, one of the older beavers had climbed up a large willow bough and gnawed a smaller branch off of it. Later I saw him towing his prize toward the dam. Upon reaching it,  he dove under the ice and presumably went into the lodge.
Julia busts a large chuck of ice down into the water
In the last few days we've been experiencing a thaw, and the beavers have taken this opportunity to clear the pond of much of its ice. They do this by widening the holes that have developed around the dams and stream channels –including the hole that I chiseled out. They break the ice in a variety of ways, but the most common method is to climb up onto it and use their weight to bust it down into the water. This method is the easiest and the most effective. Occasionally, a beaver will begin a new hole in the ice by using its head to smash up through it from beneath. From my perspective on shore, all-of-a-sudden, a beaver head just pops up through the ice –surprise!
The muskrat isn't able to break up ice like the beavers
The muskrats stay active all winter and have been doing their part to help draw down the beavers’ food reserves. The muskrat kits that were born in the fall, are beginning to resemble their parents now –so much so that I have trouble telling them apart. In a previous bog entry I wrote about how muskrats benefit from the work of beavers. Indeed, everything from food to housing is provided by their beneficent larger cousins. The muskrats also benefit from the ice removal services that the beavers provide. Definitely the muskrats are ill-equipped to perform this task for themselves.

The beaver confronts a Great Blue Heron in its "front yard"
2 weeks ago we had a Great Blue Heron around the pond system. Almost every year, there’s one of these guys that tries to over-winter in the area. They need to fish to survive, and as long as they can find some open water somewhere, they can sometimes manage to eke out a living. A few years ago, one Great Blue would ply his trade right in one of the beavers’ ice holes. This lead to some interesting interactions. The beavers weren't exactly afraid of the heron, but they did negotiate around him with some caution. I imagine the equivalent would be for one of us to confront a Pterodactyl.
The mink also takes advantage of the beavers' ice holes

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