Winter Beaver Activity
We had been worried about a apparent lack of beaver activity over the winter, but there were finally some sightings of fresh bark gnawing along the Lake Trail on the western shore of Lake Runnemede during early March. One of our photographers saw a young beaver swimming in that area yesterday. In addition to whatever food they stockpile in fall, the lake beaver have access to Nymphaea rootstocks that are abundant in the substrate of that section of the lake, so there is no need for them to move above ground in winter, even though that section of the Lake only completely freezes over during sustained cold (below zero F) periods.
They build a second lodge on the western arm of the Lake, directly across the water from the old lodge along the western shore. We thought that they may have moved, but there were fresh tracks sighted in snow on the old lodge, so they may actually occupy both.
We consider the Lake beaver to be a keystone species here, primarily because of their relationship with the aquatic flora which is the backdrop for the aquatic ecosystem. They harvest a great deal of White Water Lily (Nymphaea tuberosa) which apparently both limits the encroachment but increases the density of the extensive water lily glade in that section of the lake. They also dig channels on the lake bottom and "prune" the thick Coontail (Ceratophyllum demersum) growth near the lodges, which in turn allows the rooted macrophytes, including the rare Pondweeds (Potamogeton) to re-establish in spring. Thus this section of the lake, which also includes most of the dozens of springs that feed the lake with calcareous ground water, has the highest biodiversity in the Lake.
Thus the departure of the Lake beaver here could cause a calamitous decline in the overall health of the Lake.
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I should add that at least one, possibly more, young beaver built a dam in the Pulk Hole Brook wetlands to the east of the Lake back in 2021 and maintained that dam through last summer. We believe that this (these) beaver moved in upstream from the Connecticut River, rather than from the lake beaver family, however, since there were cuttings on the river side of Rte. 5. We monitored this activity closely, particularly for signs of them clogging the culvert that the Pulk Hole Brook travels under Rte. 5. We have a beaver deceiver (thank you, Skip Lisle!) and wire fence to prevent them from working that culvert and checked that area frequently with a drone to make sure that it remained clear.
We expected the new beaver to build a lodge, but they haven't. Instead, there was an underground burrow just upstream from the dam. There was no sign of activity there either this winter. It is more likely that beaver here may have moved on. These wetlands are limited in size and while they abound with favored building material (primarily speckled alder), there is not a whole lot of food there, or nearby. There is also a lot of human activity, including having to cross Rte. 5, which is a busy highway. There is no indication that the river beaver moved into the Lake at all, although there are some smaller Nymphaea glades along the eastern shore of the Lake.
Unlike the lake beaver on which help maintain an ecological equilibrium in the Lake, the occasional foray by offspring or new beaver into the adjacent wetlands always warrants careful observation and sometimes actions to curtail their dam-building activities if they threaten adjacent private land. As mentioned earlier, we have a beaver deceiver to protect the culvert under Rte 5, and we also have a beaver baffle, installed by Vermont Fish and Wildlife, which has helped us maintain a causeway which separates the lake from adjacent wetlands north of the Lake within the Hubbard Brook watershed.
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