The Nina Mason Pulliam EcoLab has two colonies of beaver–one in the main pond and another in the beaver pond along the West Barkchip Trail. Each of these colonies has two lodges, a network of beaver channels leading from the lodge to the food source, and up to six beaver. Beaver dig channels through wetlands to allow them easy access to their food supply. Beaver will fell small trees and shrubs along these channels and either eat them on the spot or transport them back along the channel to their lodges or food caches. In the fall, beaver often work extra hard cutting small trees for food, such as green ash, dogwood, and willow, and bring those cut pieces back to place in their underwater food cache. At the NMP EcoLab, a food cache is often visible in the water of the main pond along the North Shore Trail just east of the beaver lodge at the base of a large sycamore. Several beaver channels are visible from the Rustic and East Barkchip Trails.
Beaver in the NMP EcoLab concentrate their feeding operations in different areas each season. After cutting the saplings in a particular area, say, along the Rustic Trail, they might leave the area alone for a year before cutting again. This allows the cut stumps to resprout and grow to a size worth feeding on a second time. The beaver are farmers – they create an environment that allows their food to grow, then harvest at regular intervals.
You may find very large trees that are girdled at the base by beaver in the EcoLab. Why would beaver kill these huge trees? Certainly not for food–they don’t contain the fresh, soft cambium layer beaver love in smaller trees. They are too big to be transported to the lodge for use as building material. Perhaps they kill these large trees to reduce the shade, so that the small saplings that they do feed on can grow. Or perhaps they do it to keep their constantly growing teeth from getting too long.
You won’t find many dams in the EcoLab. Crooked Creek tends to be too deep for the beaver to dam. They are working constantly, however, to stop the flow of water out of the main pond and in other areas. EcoLab staff have to consistently remove their handiwork to keep the EcoLab trails from flooding. Beaver apparently have a lot of time on their hands!