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...
and the camera at the edge of the meadow had many pictures of work being done to reduce fuel, 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 for 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
