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A Partnership of UNH Cooperative Extension and NH Fish and Game

Beavers

In comic books and in Hollywood movies, arch-villains are often highly mechanized and possess awesome super powers. We watch battles unfold pitting good versus evil as they unleash their devious plans against each other for control of the earth.

Landowners and communities are often forced to close trails, roads, and bridges due to beaver activity that prevents use.Here in New Hampshire, many face an equally colorful and tenacious foe in the form of a large, robust rodent – the beaver. This worthy adversary is able to decimate well-tended orchards and landscape trees, stop streams, and flood out roads, fields and basements in a single night.  

They seem to possess a singlemindedness of purpose that can appear malevolent, bordering on maniacal, as they continually thwart mankinds efforts to control their activities.

According to Webster’s Dictionary, beavers are large, semi-aquatic rodents having webbed hind feet and a broad flat tail, constructing dams and underwater lodges, and yielding valuable fur and castor. Hardly the definition of a cunning and formidable adversary, but who ever said a villain can’t be cute.

History

An aerial view of the Meadowbrook property in Sandwich, NH shows the large scale impact beavers can have on the landscape. (photo by John Pries)Historically, beavers have had a big impact on our landscape by periodically flooding large areas along almost every watercourse in the state. Some of these beaver ponds were hundreds of acres in size and they provided habitat for a variety of other species.

According to Helenette Silver in her book, New Hampshire Game and Furbearers – A History, “More often than not beaver were responsible for the laying out of towns and highways.  Colonists built where they could take advantage of the wild grass in beaver meadows to feed their cattle.  Beaver dams served as bridges for crossing swamp and streams.  Mills were operated on the power of their dams”.

In early settlement times, fur was used widely by native Americans and Europeans as currency, and beaver pelts in particular were especially valuable for making hats in Europe. By the late 1800s, beavers had disappeared from NH’s landscape.

According to NH Fish and Game, six beaver were released in the state between 1926 and 1930 as part of a restocking program. By 1955, the entire state was repopulated, and beaver are now found again in nearly every watercourse in the state.

Biology

Beavers are vegetarians, eating leaves, bark, twigs, sprouts, fruits and buds of shrubs and trees, as well as aquatic plants such as sedges and rushes. They live in extended family groups called colonies, and young beavers often disperse to establish new colonies when they are two years old.

An adequate food supply is essential for beaver colonization. A beaver colony will build a dam (or series of dams), flood an area, and remain there until their food supply is depleted.  Then they will abandon their carefully-tended dam and move to an area with a better food supply to create a new dam.  When the old dam is no longer being maintained, it will weaken over time and eventually become breached, releasing the water and draining the old beaver pond.  Over time, grassy meadows, shrubs and eventually new trees will become established on the enriched soils in this newly drained area.  Eventually, beavers may move back in when the food supply again becomes suitable for their occupation.

Ecology

One of the remarkable things about beaver is that while most wildlife species will look for suitable habitat, beavers choose to create their own habitat. Awkward on land, beavers flood areas so they can easily reach and store their food supplies near their lodges.  And while they are creating their own habitat, they simultaneously provide habitat that suits the needs of many other animal species.

Great blue herons, mink, muskrats, ducks and spring peepers are only a few of the many wildlife species that benefits from the wetlands that beavers create.

Beaver ponds and wetlands also provide important habitats for species listed in NH’s Wildlife Action Plan as species of conservation concern such as blandings turtles, New England cottontails, northern harriers, least bitterns, osprey and spotted turtles.

With all these benefits, how can we find compromises that allow beavers to live among us?

Depending on what you are trying to protect, you have a few options to deter beavers and/or minimize the effects of their activities.

Exclusion:
Individual trees can be protected by wrapping them with hardware cloth. Ornamental plots, culverts, and small ponds can be fenced with small mesh woven wire fences.

Cultural Control:
Eliminating potential food supplies and habitat by clearing trees and shrubs near ponds, and keeping crops at least 100 yards from streams and ponds may persuade beaver to not occupy, or to leave an area.

Water Control with Beaver Pipes:
The installation of beaver pipes is an effective way to control water levels and keep beaver from flooding valuable timber stands, roads, and other areas.  Beaver’s keen senses immediately detect flowing water and the beaver will respond to any breaches of their dams by quickly repairing holes to ensure that the water in their pond stays at a suitable level.  Beaver pipes are placed with the intake structure underwater so that beavers will be less likely to recognize the water flow.  The outlet end of the beaver pipe should also be underwater, or if that is not possible, a standpipe can be used to regulate the water level in the pond and minimize the sound of moving water.

Below are some photos of a modified “Clemson Beaver Pond Leveler” that Steve Eisenhaure, UNH Woodland Manager, and his students installed this past summer on a UNH property in Durham to lower pond levels around homes in a nearby subdivision, and to keep good, functioning wetland habitats intact for their wildlife benefits.

The intake pipe is set in place.

The intake pipe is installed.

To eliminate the sound of water trickling, which can result in beavers attempting to dam up an area, the intake pipe is submerged under water.

The intake pipe of the pond leveler should always be under water, preferably a minimum of 2 feet deep. Note that these photos were taken in early summer 2016, when water levels were very low.

As tireless and obstinate as they may seem, when it comes to the important role they play in creating habitat, beavers are not villains at all – and to some they may even be considered superheroes. 

For more information about beaver biology and habitat, visit: wildlife.state.nh.us/wildlife/profiles/beaver.html. To learn more about beaver dams and management, read Beavers and Their Control from UNH Cooperative Extension

By Wendy Scribner, UNH Cooperative Extension
Fall 2016 Taking Action for Wildlife Newsletter

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