I was walking our dog, AJ, in Les Arends Forest Preserve in Batavia last weekend, when I spotted the heavy-duty beaver work you see in these photos.

Enterprising lot, those beavers. You can see in the background, they’ve made some significant progress building a dam between the shoreline and one of the wooded, floodplain islands that are part of the preserve.

According to the Illinois Department of Natural Resources, a flurry of beaver activity occurs in September and October as beavers prepare for winter. Tree saplings are cut and anchored underwater outside the lodge or den. This feed pile can reach a size of 3 to 6 feet deep and 30 to 40 feet across. When ice forms, the beavers swim out of the underwater den entrance, cut branches from their feed pile and return to their den to eat the bark.

“Beavers fell trees by cutting the first notch at a convenient height and then making a second one about three inches below the first. They chew out the bark and wood chip by chip until the tree snaps and falls. The beaver is unable to drop a tree in a specific spot or at a specific angle. However, most trees that grow along streams tend to lean toward the water, so they usually fall into the water when cut,” the IDNR website says.

Jeff Long, of the Fox Valley Park District, said on Facebook that he saw this beaver dam on Big Rock Creek (near Big Rock Forest Preserve & Quarry Lake). “It’s amazing how fast they construct these things,” he said.

You can read more about our forest preserves and wildlife on the Kane County Forest Preserve District website and the Forest Preserve District of Kane County Facebook page.