Most folks know that stream-flow ponds impounded by dams built of sticks, stones, and mud are created by beavers. Conical or dome-shaped lodges surrounded by water are also recognizable signs of Castor canadensis. As summer slips into autumn, reminding us that winter is not that far away, how do we know that beavers are actually in residence within a given pond complex? Here are four signs of active beaver occupancy that one can easily find:
♦ Look for an abundance of freshly cut trees, saplings, and woody shrub stems in the vicinity of the pond. During autumn, beavers shift into overtime for food gathering. A colony may need to store hundreds of woody stems to have enough food for the winter. Fresh-looking sap and wood chips will be obvious evidence on and around recently cut stems.
♦ Freshly peeled sticks and mud will have been added to the dam. It is critical that the dam is strong enough to hold. The pond and its associated canals allow these semi-aquatic rodents an effective means of minimizing their exposure to predators while collecting food. In addition, the pond’s watery environment makes it easier for beavers to access and transport their foods. A pond is perfect for the creation of a safe, weatherproof lodge in which beavers can escape from enemies, rest, keep warm, mate, raise families, and eat during winter.
♦ Look for fresh mud plastered on the lodge. In all but the most gravel-bottomed habitats, beavers will gather and apply a seal of mud to the surface of the lodge, covering all but the air vent. This serves both as weather shield and, when frozen, a cement-hard fortification against predators. In our region, coyotes, bobcats, occasionally bears, and historically wolves and cougars all prey(ed) on beavers.
♦ Seek to find evidence of food caches. In Preparation for winter, beavers collect branches and construct a raft of less desirable species whose collective water logged weight will push down and hold the food branches they like, including poplars, willows, maples, red osier dogwood, and yellow birch stems. When the pond is frozen, the beavers benefit by having underwater access to their preferred foods. The raft’s branch tips can be seen protruding from the water or even the frozen pond’s icy surface. Species that are not generally eaten, such as eastern hemlock, red spruce, white pine, and alder will be visible poking above the surface of the raft.
Susan C. Morse is founder and program director of Keeping Track in Huntington, Vermont.