Biodiversity Benefits of Beaver in Iowa
Beavers are keystone species, creating wetland habitat beneficial for many other species of plants, amphibians, birds, and small mammals in Iowa.
Both beaver lodges (where they nest) and beaver dams (to create a pond to keep the lodge entrance underwater) have many benefits to biodiversity.
At one point, approximately a quarter of Iowa was wetland—a number that has been reduced significantly since, with something near 5% wetland area remaining. With that comes the decline of several native plants and species. Meads Milkweed (Asclepias meadii) and Prairie Bush Clover (Lespedeza prairie) are federally threatened species in Iowa. Dakota skipper, a butterfly native to Iowa, is also experiencing a sharp decline due to habitat loss. Many of the Iowa endangered species list—in some way—rely on the wetlands that have now disappeared the same ones that beavers are actively trying to build.
Dakota skipper on Echinacea pallida. Photo by Eric Runquist
When beavers build lodges, they prefer the entrance to the lodge to be underwater, which helps them be safer from threats above water. Beavers are excellent swimmers and can hold their breath for around 20 minutes. Sometimes, when the water levels drop, the entrance and exit to the lodge dry up. To keep that from happening, beavers build dams that create a ponding effect, in turn helping the lodge entrance stay underwater.
Beaver crawling through plant debris. Photo by Deborah Freeman
Beaver colonies (family) will sometimes build multiple dams and create an incredible ponding system with those dams, which is what we call a wetland. This habitat is crucial for Iowa wildlife, including Great Blue Herons, which greatly benefit from beavers to help create the perfect nests for their eggs. Wood ducks prefer slower-moving water and also benefit from beavers.
Because beavers are experts at managing water levels, they help many amphibians survive through the dry summer, maintaining pond height all summer long by managing dams.
Wood duck
I once got a call from a gentleman who was a duck hunter and wanted me to relocate the beaver colony in the pond on the property he hunted on. When I informed him that beavers create a richer habitat and will attract more ducks over time, he was amused, but still not convinced. “I also want to be able to fish here, and they are eating all the fish.”
Nope, beavers don’t eat fish! In fact, beavers dig out tunnels into the floor of the ponds, which benefit fish. Dam construction can also recharge the groundwater, helping to cool streams and providing a more consistent water temperature for fish.
Many aquatic insects benefit from beaver dams, which then in turn create more food for bats, who can come to the pond to feed.
Beaver dam and the resulting pond
As you begin to explore this complex web of interactions— one thing becomes clear. Beavers are a friend and ally to many species in Iowa, that make Iowa a beautiful and wild landscape.
With on-site management, we can begin to coexist with beavers. By using one of the many proven methods like pond-levelers, culvert guards, and tree protection, Iowa can begin to coexist.
A beaver swimming across its pond
Further Learning:
Eager by Ben Goldfarb (my favorite book on beavers!)
Project Beaver Resources to learn more about coexistence
Human Beaver Coexistence Fund graphic
