Although most of the Northeast is snow-free, parts of northern New England still have a while to go before bare ground is visible. Most beaver ponds, however, are open and the beavers have been taking advantage of their ability to access fresh food after a long winter of water-logged woody plants. While this particular beaver is dining on bark, most beavers head for any green plants, buds, grasses, etc. that are poking their heads above the ground. A particular beaver delicacy this time of year are the leaves and blossoms of skunk cabbage.
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A recent light snow provided an opportunity to confirm that northern New England beavers have gained access to land and are seeing the sun for the first time in several months. They, along with any beavers living north of the 39th parallel, may well reap some benefit from the change in our climate. Further south, there is no real winter and beavers do not have to cope with a limited amount of stored food for there is usually no ice on ponds. Milder winters and early springs mean more time for Northeastern beavers to access herbaceous food and fresh bark, and less time locked under the ice.
Unbeknownst to many, a large portion of a beaver’s spring, summer, and fall diet consists of herbaceous food – grasses, sedges, ferns, fungi, berries, mushrooms, duckweed and even algae. When beavers first leave their ponds in the spring, one of the first foods they head for is skunk cabbage, as it is one of the earliest flowering plants to emerge (often when snow is still on the ground). Beavers also relish the new foliage of aspen, willow and alders. When they are accessible, the rhizomes, leaves and flowers of both yellow and white pond lilies are favorite foods. Come late fall, when lush greenery has disappeared, beavers up their intake of bark (cambium) and store a pile of branches on the bottom of the pond close to their lodge, where they have underwater access to it all winter.
As Skunk Cabbage grows, it absorbs oxygen, and this allows it to produce heat through a process known as thermogenesis. This heat is responsible for the fact that Skunk Cabbage is one of the earliest plants to flower in the spring.
Skunk Cabbage’s flower has two components – the flower-bearing, round spadix and the hood-like spathe that surrounds it. The spadix is able to maintain its temperature at about 68°F., creating a little warming hut inside the spathe for the few insects out this early in the spring. Fueled by the reserved starch in the plant’s underground rhizome, the spadix is able to exceed the temperature outside the spathe by as much as 77°F. for a period of two to three weeks. The combination of the heat produced and the dark, heat-absorbing spathe can cause the snow around the plant to melt. If the ambient temperature drops below 37.4°F., the plant can shut down the heating mechanism until the air temperature rises again. (Thanks to Sadie Brown for photo op.)
When Black Bears emerge from their dens in the spring, they have lost between 15 and 40 percent of their weight, and food is in short supply. About 85% of a bear’s diet is vegetation, and most trees and shrubs have not leafed out yet. Black Bears often head to wetlands, where grasses and sedges are beginning to sprout. Nutritionally the shoots of these plants provide them with some of the protein they need, but this source of nutrients is short-lived, as the shoots are tender for only a few days before hardening with cellulose. Roots, bulbs, corms and tubers of plants such as Skunk Cabbage and Jack-in-the-Pulpit are sought after, as are the buds of trees, but bears must wait for the bountiful supply of berries and nuts that mature in summer and fall. Those bears living near humans come to rely on foods inadvertently provided by these humans, such as highly nutritional sunflower seeds being fed to birds. One can hardly blame bears for taking advantage of this available source of food during this challenging time. Feeders and cans containing seed should be put in a bear-proof location if you don’t want to encourage “nuisance” bears which, unfortunately, are sometimes killed just for trying not to starve to death.