Beavers at Summer Star

By Dan Stimson, Assistant Director of Stewardship at Sudbury Valley Trustees.

As you walk the trails at Summer Star Wildlife Sanctuary, you will see many signs of how the landscape has been shaped by humans over the years: Stone walls, forest roads, tree stumps from past forest harvesting, and the placement of the trail you are walking on are some of the more obvious. But there are now signs that the landscape is being shaped by other creatures as well; beavers are making their presence known!

Beavers build a lodge out of branches, mud and leaves they’ve gathered from in and around the pond.  They excavate a chamber inside the lodge and will live in it throughout the year. This photo of a lodge  near Summer Stat Wildlife Sanctuary was taken by Wilson Acuna.
Beavers build a lodge out of branches, mud and leaves they’ve gathered from in and around the pond. They excavate a chamber inside the lodge and will live in it throughout the year. This photo of a lodge near Summer Stat Wildlife Sanctuary was taken by Wilson Acuna.

Beavers are the largest rodent found in Massachusetts, with adults weighing between 35 and 80 pounds and reaching a length of over four feet (including their wide, flat tail). They are a common part of our landscape now, but due to fur trading and farming, they were once extirpated from Massachusetts.

For centuries, beaver fur had been a popular choice as a fabric for warm clothing, but by the early 1600s, the European fur trade had resulted in a massive depletion of European beavers. Fur traders were then able to take advantage of the new European colonization of North America, and they introduced American beavers to the global market. This trapping pressure, coupled with the transformation of the New England landscape from forest habitat to open farmland, resulted in Massachusetts recording its last known sighting of a beaver by 1750.

When farmers started abandoning their farms in the late 1800s, however, much of the landscape of Massachusetts began returning to forested habitat, becoming more welcoming to wildlife such as beavers. In 1928, the first new sighting of a beaver was recorded in West Stockbridge.

The entrance of a beaver lodge is accessible under water. This photo by Jesse Koyen shows the lodge  extending towards deeper water. This adaptation is often built by beavers when water levels drop in  order to ensure that the entrance remains secure from predators and to enable the beavers to access the pond, and cached food, beneath winter ice.
The entrance of a beaver lodge is accessible under water. This photo by Jesse Koyen shows the lodge extending towards deeper water. This adaptation is often built by beavers when water levels drop in order to ensure that the entrance remains secure from predators and to enable the beavers to access the pond, and cached food, beneath winter ice.

A species once primarily valued for its fur is now understood to be extremely important for much of our local wildlife. The beaver has a unique role in our forest ecosystem because of its rare ability to transform its habitat.

Beavers spend the vast majority of their lives in water and are driven to increase the size of their habitat by damming streams and rivers; this grants them greater access to their food source as well as more protection from predators. Their labor also expands the habitat for all sorts of wildlife. Wood ducks often breed and nest in and around these ponds. Great blue herons use beaver wetlands for hunting grounds, and they nest in the tops of large dead trees with flooded roots. Frogs, turtles, insects, snakes, aquatic plants, songbirds, raptors, fish, salamanders, and mammals—nearly all of the wildlife in our forests—make use of the drastically transformed habitats caused by beaver activity. Humans also benefit. Where many of our wetlands have been lost over the years to development, beaver dams help to re-establish flood storage, improve water quality, and recharge groundwater.

The Summer Star beavers are busy at work on Wrack Meadow Brook, a tributary to the Assabet River. They have likely moved north from other beaver colonies along the brook south of the Sanctuary, on lands owned by Sudbury Valley Trustees, the Town of Berlin, and the Town of Boylston. These colonies consist of family units of around eight individuals—beavers may live more than 20 years and generally mate for life—that include the year’s kits as well as the offspring from the previous year. After the second year, offspring will venture out and claim their own new areas.

Look for signs of beavers along the trail, now that their pond has neared the path. The new flooding will be accompanied by chewed stems, tracks, scent mounds that mark their territory, glimpses of their dams along the brook, and all of the increased signs of the other wildlife benefiting from their work.

As conditions change, portions of the trail will likely be closed temporarily. We’ll do our best to post updated signs, but please keep in mind that you may need to turn around and return the way you came.

Beavers build dams like this one in order to raise water levels and increase the size of their pond. This gives them access to a larger area in which to gather food and provides more depth of water around the entrance of their lodge. Beavers will often build multiple dams along water courses, raising its level in steps. This photo was taken at Summer Star Wildlife Sanctuary by Wilson Acuna.
Beavers build dams like this one in order to raise water levels and increase the size of their pond. This gives them access to a larger area in which to gather food and provides more depth of water around the entrance of their lodge. Beavers will often build multiple dams along water courses, raising its level in steps. This photo was taken at Summer Star Wildlife Sanctuary by Wilson Acuna.

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