On 3 January, Herb and I visited four of the trail cameras that I have in Glen Valley Park, for the first time in two weeks. With about 10 inches of snow on the ground and around minus 6 C temperatures, it was a cold business. I appreciated Herb’s help in changing dead camera batteries and  holding memory cards while I switched them for fresh ones. Fingers numb with cold can easily drop things into the loose, fluffy snow. 

The camera at the “beaver tree” had stored over a hundred short videos of a beaver at work, cutting the big cottonwood tree.

 I have to  assume that this huge task is being done by a lone beaver, as during these many weeks of camera surveillance, never more than one beaver has appeared in the pictures. If it is alone, the question of why it should tackle such a large tree defies imagination. Trails in the snow lead out from the stream to places where smaller cottonwoods have been cut and dragged back to the creek. Of course there is food for a beaver in the smaller branches of the big cottonwood, but a beaver could starve before reaching that.

 Now and then another animal visits the tree, as if to inspect the beaver’s progress. The camera held pictures of a red squirrel, a coyote and two raccoons. 

The raccoons demonstrated some interesting behaviour, which I have not seen before. They deliberately scooted their bottoms on a large bare root at the base of the tree, obviously depositing an intentional scent mark there (see video below).

Video of Beaver at work

On Saturday, when I visited the trail camera that I have monitoring a large cottonwood tree in Glen Valley Park, I found over 100 paired 10 second videos and still photos of beaver at work on the big tree. Mark has edited several of the videos and made a longer, but still short, video, which can be seen by either clicking on the image below, or on this link:  https://youtu.be/OOxK2zg6BMY

I measured the tree, placing my tape just above the beaver cut. It is 102 inches in circumference, which translates to 32 inches in diameter. Cutting such a large tree is a daunting task for beavers. I have been assuming that there are several beavers but to date, I have photographic evidence of only one. I will try to keep a camera at this tree, monitoring the beavers’ work, until the tree falls, or the beaver give up.

Lars.

Beavers at work!

On Saturday, 12 December, Herb and I went to the Glen Canyon Park to check my trail cameras. I finally got some pictures of beavers at work! 

My son, Mark, made a video from four of the best of several segments of beavers at Powers Creek. You can see the video itself here. 

You will notice that all of the beavers are at work on land, one working at cutting the big cottonwood tree that I mentioned in a previous message, and the others dragging small tree trunks and branches toward the creek. None of them are just fresh up, wet and cold, out of the creek. This seems to support my idea that my failure to get pictures of beavers earlier were because the other cameras were located to photograph beavers in the creek or at creek-side, and my cameras were not being triggered by their cold bodies. Trail cameras are triggered by both body heat and movement.

I will remember to measure the girth of the large cottonwood that they are working at cutting. The deepest notch is on the side toward the creek, and does not show in the videos. Beavers are clever engineers but they do not know in which direction their trees will fall. They just cut all around a tree with their chisel-like teeth until it falls.

On Sunday afternoon, 29 November, Herb and I checked the trail cameras that I have in Glen Canyon Park. Only two of them had been in operation, as on my last visit, I forgot to reset the camera at the main creek crossing. The camera at the log bridge had recorded the visit of a raccoon…

The camera at the edge of the meadow had many pictures of work being done in the park to clear dead standing trees and woody debris, as a prevention measure to reduce danger from wild fires. The various photos on that camera showed the work crew in action, cutting trees, removing the logs and chipping the branches.

The beavers have been very busy, working like beavers do--and I am amazed to see the large size of one of the trees that they are working at falling (second picture). This one big cottonwood is about 10 feet in circumference at its base, where you can see the beavers are making their cut. On my next visit, I will carry a tape measure or a piece of cord to determine its size. Cutting a tree this size has to be spread over several days and nights. I first noticed that they had begun work on this tree when I visited the area on Monday a week ago. At first, I found it hard to believe that beavers would tackle a tree this large. But yesterday, I could see that much more work had been done. I wonder if two or more beavers work together on this? I now have a camera trained on the base of this tree. It is programmed for high quality video.

The mystery of my cameras apparently being unable to react to the comings and goings of the beavers may be related to the beavers' very heavy fur coats and the fact that they are usually wet and cold from constantly going in and out of the creek. This has been suggested by two of my Catch of the Day recipients and I have found support for that in the literature that describes how the triggers for the trail cameras function. The sensor lights which trigger the cameras are infra-red, which react to animals' body heat. They do not respond to a target which is at the same temperature as ambient temperature, that is, the temperature of the immediate environment. Perhaps if the beavers work on this large tree for long periods, their coats will warm sufficiently to trigger my camera.

Beavers eat the fruits of their labour, and they cannot go hungry waiting or this big cottonwood tree to be felled. So they continue to also cut smaller trees, which they peel, eating the bark and cambium. The upper right of the second picture shows several freshly peeled sticks in one of their food beds. Some of the peeled sticks and small logs are used to build their dams, of which they have several--well spaced along the creek. The dams raise the water level, and this facilitates movement of the trees that they
cut.

Lars