This past weekend, the wife and I packed up the kids and headed west, bound for adventure in the exotic lands beyond the bridges. As much as I love the Cape, I need to head to places with richer woods and bigger wildlife now and again. In this case we were in the Pioneer Valley, out by UMass Amherst, an area special to me and my wife. A long hike we did out there left me thinking about one particular, peculiar critter that we don’t have out here on this big sand bar. This creature creates entire ecosystems for other species using only teeth and paws. It’s the biggest and most industrious of North American rodents, the beaver.
While you may be adjusting your dial, wondering if you’re still listening to the bird report, fear not – no mammal is so intricately connected with birds as beavers. The list of birds who benefit from these furry, 80-pound engineers is long and diverse – everything from Great Blue Herons and Great Horned Owls to bluebirds and Tree Swallows make use of beaver ponds and meadows, some depend on them. Believe it or not, except for one small colony on the Upper Cape, Great Blue Herons don’t really nest on Cape Cod, mostly because we don’t have beavers – the ones you see mainly came from off Cape and likely hatched in a beaver swamp, so thank a beaver the next time you see a Great Blue Heron.
Our hike through conservation land in Northampton led us to two different earthen dams, one made by people and one made by beavers. The human dam was fine - it had created a lovely, shallow pond where we saw Wood Ducks, crayfish and water snakes, and the dam itself had been planted with all sorts of native wildflowers. But for whatever reason, the beaver dam was just better.
As we stood on it, the impact of the big rodents’ public works project was immediately obvious in all directions. The skeletons of trees were everywhere, killed by the flooding behind the dam, but housing innumerable creatures. A huge nest in one seemed to contain a family of Pteranodons, though closer inspection revealed it was Great Blue Herons. A few feet from us, a Great-crested Flycatcher entered a nest cavity in a dead tree to feed young. Elsewhere, Tree Swallows and a Yellow-bellied Sapsucker, a real woodpecker with a fake-sounding name, did the same.
A bluebird called somewhere out in the swamp. Like the Tree Swallows, it was there only because of this habitat created by the beavers in what otherwise would be dense forest. Later, when the dam fails and the pond becomes a lush meadow, it will be even better for them. A big garter snake that had been sitting on the dam slithered way, multiple shed skins showed this was a favorite spot. Even butterflies benefitted – we saw a Red Admiral caterpillar, pink and spiky, using silk to make a shelter in the leaf of a false nettle growing on the dam, then a striking black and orange adult landed nearby.
Lots of things we didn’t see also benefit – Wood Ducks, Black Ducks, and Hooded Mergansers all thrive in beaver swamps, and trail cameras trained on that dam recorded bobcats, bears, and a parade of other mammals crisscrossing it.
All of this makes me jealous that we don’t have beavers, and the rich wetlands they create, here on the Cape and Islands. But like a lot of wildlife, including the bears all over the news lately, beavers are increasing in the southeastern part of the state. So it may not be long before the world’s second-largest rodent paddles the width of the canal or waddles across the bridge. And when we do finally get beavers on the Cape, well, it will be about dam time.
