Beavers Are Back

Illustration by Tabitha Walters

The first signs were subtle but undeniable: last November, Matthaei Botanical Garden staff began noticing trees stripped of bark or cut down entirely, leaving only a pointed stump behind, and a pile of leaves and sticks along the edge of the creek slowly growing into an unmistakable dam. Those efforts soon raised the level of the creek by more than a foot for several hundred yards upstream.

Long coveted for their fur, beaver had been trapped to extinction locally by the mid-nineteenth century. Now they are staging a rapid comeback, thanks in large part to improved water quality. Their long, waterproof outer layer of fur provides insulation essential to their survival but easily becomes gummed up by oily pollutants. As these have been removed from waterways, their numbers and range have greatly expanded.

Matthaei and Nichols Arboretum natural areas program lead Jeff Plakke report that neighbors along Fleming Creek have also noticed beaver activity, including a second dam further downstream. Over the winter, snow and rain twice washed out the center of the original dam; despite rebuilding, it never returned to its previous height. By June, however, it became clear that another kind of growth was happening when trail cams recorded an adult beaver with two kits.

While garden staff were quick to celebrate their tiny new neighbors—an online poll named the family the Gnawsons—living alongside a sixty-pound rodent that engineers its environment to its own liking is not for everyone. “Beavers took down another tree on the boardwalk” at Furstenberg Nature area, an A2 Fix It user reported in early September.

Natural Areas Preservation staff first saw signs of beaver in 2019, and they’ve also been reported at Gallup Park, the South Pond Nature Area, and the Barton Nature Area. Given their continuing territorial expansion, expect to see more of them in the future.