A beaver can fell a cottonwood tree in just a few hours. Hundreds in a year. The beaver doesn't chew through the whole trunk. Just enough to make the tree unstable. It then retreats and lets the wind do the rest. It cuts branches into more manageable lengths and then swims them down a network of purpose-built canals towards the dam. The pond gives this beaver protection from predators and the canals allow it to forage far into the forest carrying many times its own weight with ease.

Autumn is the busiest time of year for beavers. It won't be so easy to make repairs when the pond is frozen over. The sound of running water is their stimulus to shore up gaps with timber and plug leaks with mud. Moose come here from the forests around to feed on weeds that thrive in the beaver's shallow pond. The weed is rich in vital sodium that the forest can't easily provide. But now that winter is approaching another essential role for the dam is revealed. These smaller branches are not for fixing the dam. They're for eating. The beaver secures them to the mud in the lake bottom. In just a few weeks this lake will be frozen and the beavers won't be able to cut and move trees. But they will be able to swim right

under the ice to feed from this underwater ladder. Moose also eat twigs and branches and often try to take advantage of the beaver's hard labor. This young male is getting a little too close to the beaver's ladder.