Beavers: Nature’s Eager and Industrious Engineer

Beavers: Nature’s Eager and Industrious Engineer

Last week I traveled to New Hampshire to walk the forest lands my grandparents purchased in the early 1930s. In the woods are beaver ponds, each in a different stage of use or abandonment. March is a perfect time to get a close look at each of them when the still frozen ground and ice makes for easier walking on wetlands.

In the early 1980s beavers moved onto the land by following a small stream that flows through the property and into a larger flowing water source called Kemp Brook. The stream originates from a spring hidden within a hillside, forested boulder field. In March and April, it can be heard gurgling below the rocks and then emerges as a rivulet of surface water. Increasing to a small stream, it meanders downhill through the woods for half a mile before emptying into Kemp Brook. During the past 40 years beavers built three dams on this small stream, creating three ponds, the largest more than 300 feet across. In the middle of each pond, they constructed a lodge where they raised successive generations of North American beavers – Caster canadensis.

Beavers build dams and create ponds for safety, shelter and food. A stream is not big or deep enough for beavers to hide from predators but a pond serves as a moat to surround their lodge and provides a safe travel route to shore and their feeding grounds.

“Removing the shoreline trees allows more sunlight that encourages more palatable shrubs and saplings like willow, birch, and aspen. When the food supply near the pond is exhausted the beavers move on, leaving dams that become leakier every year. Eventually the pond drains, and the marsh becomes a meadow, a shrub swamp, then finally a forest with its roots in rich beaver soil. Few other mammals, besides humans and perhaps elephants, can so drastically change their habitat to suit their needs,” wrote Janine M. Benyus, from “The Field Guide to Wildlife Habitats of the Eastern United States.”

The first pond we discovered some 40 years ago was abandoned about 5 years later, and the dam has since disintegrated, leaving only a long lump covered in grasses and shrubs. Today we call it the beaver meadow. A few years back I built a small bench and placed it on a knoll overlooking the meadow. It’s a good spot for birdwatching and observing wildlife. The only traces of the old pond are a few old dead pine trees that had been flooded out and that small stream still ambling through on its way to Kemp Brook. Now there are meadow grasses and small saplings of birch and maple sprouting. Over the next few years, it will likely be unrecognizable as an old beaver pond.

The second pond had the most activity during the past few decades. The industrious beaver moved up stream from the first pond and used an old logging skid road for the base, constructing a new dam about 75 feet long. Pond No. 2 is closer to the source of the stream and served its purpose for many years. The beavers abandoned this second pond about 5 years ago. Then returned in 2021 and made repairs to the dam. It didn’t look as if they had repaired the lodge, and there were no signs they had taken up residence, other than the dam repair.

The pond is, however, home to many others. Peepers, tree frogs and other amphibians, including a healthy population of red spotted salamanders, use it to lay eggs. Wood ducks use the nesting box I installed a few years back (a gift to me from Dick Waterman of Sprague). But last week the dam was leaking and the water was down, and unless the beavers return this spring it will begin the slow process of reverting to wetland and meadow.

The most recent dam and pond, No. 3, are about five years old and much smaller than the first two. Like the second pond, the beavers also used a logging skid road as the base of the dam – though only about 20 feet of it. It was only active for one year and the dam is now leaking. If the beavers return, wandering back up from Kemp Brook via the small forest stream, this may be the first location they re-occupy.

The quote above from Janine M. Benyus perfectly describes my experience with beavers on our property. I am glad they moved in, altered the habitat and created ponds that benefit countless other animals. Perhaps later this spring I’ll find the dams repaired and a new family of Caster canadensis moving in.

The property my grandparents purchased in 1933 is within the traditional lands of the Abenaki Tribe, who stewarded the land for many generations. The Tribe likely understood the ways and habits of beavers using the Kemp Brook watershed better than the colonists who moved to the area beginning in the 17th century. By the late 1800s trapping had nearly eliminated beavers from New Hampshire and restocking efforts began with releasing six beavers between 1926 and 1930. When my grandparents arrived in 1933 there were no beavers left in Kemp Brook. By the 1970s, they were back, this time to stay.

For those interested in learning more about the North American beaver and their positive impact on the land I suggest a book published in 2018 called “Eager: The Surprising, Secret Life of Beavers and Why They Matter” by Ben Goldfarb.

Here in The Last Green Valley and throughout New England there is a healthy population of beavers. They are fascinating animals who alter their habitat to suit their needs for safety, shelter and food. Yes, they can be a nuisance when their urge to control flowing water creates flooding on private land and roads, however they also do good by creating new habitat rich in resources for many other creatures.

Information for this column was gleaned from “The Field Guide to Wildlife Habitat of the Eastern United States,” by Janine M. Benyus, and “Eager: The Surprising, Secret Life of Beavers and Why They Matter,” by Ben Goldfarb, and New Hampshire Fish and Game.

Bill Reid is the Chief Ranger of The Last Green Valley National Heritage Corridor and can be reached at 860-774-3300 or bill@tlgv.org

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