Beaver Lodge Occupancy
Beaver Lodge Occupancy Surveys
By Larry Roy. Banner photo Phil Walker.
In the late winter/early spring of 2021, some 30 volunteers - including at least 13 Friends of Elk Island members and some very dedicated parks biologists, performed beaver lodge occupancy surveys in Elk Island National Park. These surveys were performed in support of a larger program run by Dr. Glynnis Hood, professor of Environmental Science at the University of Alberta, Augustana Campus, and Manager of the Miquelon Lake Research Station.
Why beaver surveys? Beavers are semi-aquatic mammals that play a crucial role in shaping the landscape in and around the Beaver Hills. The dams they make create wetlands that support diverse floral and faunal communities and contribute to the knob and kettle formations that abound in this area. The trees they cut down allow shrubs, herbs and grasses room to grow, further increasing the biodiversity across the landscape. Therefore, the health of beaver populations is an indicator of the heath of ecosystems in the Beaver Hills region.
Surveys in areas that had not been sampled before involves first finding all the marshes that might support beavers. This is easily done using satellite imagery. The next step, a much more difficult one, is actually accessing those spots, which is mostly done on foot through thick brush. Once reached, the GPS locations of beaver lodges are recorded so they can be surveyed again in the future.
Beaver use of a lodge is determined by a series of clues; lodges are considered occupied when a fresh feed pile is adjacent to the lodge (Figure 1) and fresh cut trees and stumps are evident on the nearby shoreline (Figure 2). Occupied lodges are also usually devoid of growing vegetation and have new mud deposits (Figure 3).