Solutions to So-called Problems Caused by Beavers

As with wildlife in general, 'problems' caused by beavers are in the eye of the beholder. In a natural setting, what beavers do from day to day is a critical part of any ecosystem. Occasionally, however, beaver activities come in conflict with what human beings have planned for a particular piece of land. In such situations, there is never a need to resort to lethal means as a method of 'control'.

Points to consider when asked to resolve conflicts:

• Educate the public about beavers; this is a keystone species, which means that the well-being of other animals and the local environment in general are dependent on or are substantially improved by their presence and activities. Allowing the beavers to co-exist in your area shall -- overall -- result in a situation that is beneficial to people, as well.
• Long-term, beavers do not cause problem flooding, rather they reduce the chance of catastrophic flooding through their management of a particular waterway. In the short-term, problematic flooding can almost always easily be controlled by the use of strategically located water-flow devices that either fool beavers into thinking no further damming is necessary or control the upstream level of water. These devices have been shown to be effective and less costly than inhumane methods of 'management'.
• Beavers can be instrumental in preventing the spread of wildfires or the renewal of areas devastated by wildfires. See article by Ben Goldfarb for examples.
• Beavers need trees and shrubs for food and there may be concern about the killing of trees surrounding the beaver habitat. Beavers, however, only gather what they need for food, shelter and maintenance of their dam(s). Many species of plants are not at risk, but if there are specific vulnerable trees that someone wants to protect, the most effective way is to put tall, wire-mesh 'cages' around those trees. We have yet to see any beaver habitat in which the beavers have completely denuded the area.
• When lethal means are used, this is likely to increase reproductive effectiveness in the surviving beavers, resulting in higher birth rates or fecundity. One would have to kill every beaver in the area not just once, but 'forever' because others will keep filling the 'vacuum' created.

For more information, you can contact us or other groups knowledgeable about beavers. Listing a group here does not mean that the Refuge necessarily endorses or agrees with the information they provide.

• Beaver Institute, Inc.
• Beavers: Wetlands & Wildlife (non-profit) accessed 2020-04-09
• Wildlife 2000 (non-profit)
• The Beaver Deceivers (commercial) accessed 2020-04-09
• Beaver Management Forum [Facebook]
• Beaver Solutions™ (commercial) accessed 2018-07-23
• Armtec (commercial) accessed 2020-04-09

Here are some references for information on solutions or reasons why learning to cohabit with beavers is beneficial to all:

• Anonymous. undated. Beaver Solutions Flexible Pond Leveler™
• Anonymous. undated. Beaver Solutions Fence and Pipe Flow Device
• Anonymous. 2001. The Clemson Beaver Pond Leveler. Minnesota Department of Natural Resources. accessed 2019-08-13
• Boyles, Stephanie L. 2006. Report on the Efficacy and Comparative Costs of Using Flow Devices to Resolve Conflicts with North American Beavers along Roadways in the Coastal Plain of Virginia accessed 2019-05-08

This study demonstrated the cost effectiveness of using preventive measures: Following flow device installations, the estimated cost - benefit ratio was 1 to 8.37, or for every $1 spent, [Virginia Department of Transportation] saved $ 8.37.

• Callahan, Mike and Perryman, Heidi. undated. What Good Are Beavers?
• Callahan, Michael; Berube, Richard and Tourkantonis, Isabel. 2019. Billerica Municipal Beaver Management Program: 2000 - 2019 Analysis. 8 pp.

A total of 55 beaver conflict sites were studied from 2000 through 2019. This first of its kind study revealed that the sites managed with nonlethal control methods cost significantly less than sites that were managed with beaver removal. In addition, nonlethal control methods provided millions of dollars of ecological services to the town annually that would have been lost with beaver removal.

• Lazar, Julia G.; Addy, Kelly; Gold, Arthur J.; Groffman, Peter M.; McKinney, Richard A. and Kellogg, Dorothy Q.. 2015. Beaver ponds: Resurgent nitrogen sinks for rural watersheds in the northeastern United States. Journal of Environmental Quality 44(5): 1684-1693. accessed 2016-01-24

Ecosystem services may include the abatement of dryland streams (Gibson and Olden, 2014), promotion of waterbird communities (Nummi and Holopainen, 2014), increase in salmon production (Pollock et al., 2004), and the removal of reactive N from the watershed as discussed herein.

• Scarafile, Nancy. 2019. Beaver management plan, Chesterfield, NJ

The Beaver Baffler

At Unexpected Wildlife Refuge, beavers dammed three four-foot-diameter culverts under Piney Hollow Road, flooding a farmer's field across the road. Township officials decided that the only solution was to get rid of the beavers. We suggested a beaver baffler, to keep the beavers from building in the culverts. The township cooperated by building three five-foot-long cones made of heavy concrete reinforcing mesh, but we felt that the length of these would be inadequate, as beavers might build along and around them.

We enlisted the help of Brian Graff of Dolgeville, NY, who had successfully installed a beaver baffler in a road culvert near his homestead, not far from Beaversprite Sanctuary. The Graffs, along with a few other volunteers, helped clear out the culverts and installed a 15-foot-long cylindrical Beaver Baffler with three layers. The core was made of concrete reinforcing mesh wrapped with 1" by 2" mesh fencing wire, around which a larger cylinder of reinforcing mesh was placed, held by wires which kept it separated from the core by a 6" space. One end of this contraption was closed by a piece of reinforcing mesh and the other end forced into the upstream mouth of one of the culverts. We used one of the township stops in another and left the third culvert open so that beavers and other animals could pass up and down stream without having to come out on the road. The downstream ends of the two stopped culverts were capped with reinforcing mesh. All devices were kept firmly in place by metal fence posts driven deep into the bottom mud.

The Beaver Baffler developed by Graff is a modified version of the Beaver Stop™ invented by Neil Thurber of Alberta, Canada.

The installed devices dramatically lowered water level in the neighbor's field, and the beavers have not tried to rebuild around the stops.

Beaver Stop

For more information about the Beaver Stop, contact Canada Culvert.

Beaver Deceiver

This has apparently been used successfully in Snohomish County, Washington.

According to Sharon Brown of Beavers: Wetlands & Wildlife, "The shape can be rectangular, or trapezoidal, with sides at least twice the width of the culvert or spillway opening. Either metal or wood posts are used with large mesh fencing of 8, 6 or 4 gauge. The smaller the gauge #, the thicker the wire; 8 ga. is easier for beginners. If the stream bottom is muddy, a floor of the same material is laid first to prevent beavers from burrowing underneath the fence." (personal communication, 7 December 2015)

Tree Cages

To protect trees from being felled by beavers, there is a simple solution: put cages around the bases. We used cylinders of 2" by 4" by 3' heavy wire fencing. These cages should be large enough in diameter to encircle the trees with at least a 6" space between wire and trunk. A 12" space would be better, as beavers may gnaw between the wires of the mesh. Cut the horizontal wires at one end and next to the vertical wires, and then fashion the cylinder by hooking long ends around the vertical wires. The guards can be removed by merely unhooking the wires.

You can download a sheet containing this information.

Relocation (translocation)

This is almost never a satisfactory 'solution' for many reasons:

• If the habitat is suitable for beavers, more will almost certainly eventually move in.
• They are unlikely to stay where you relocate them and will move to other locations, thus they are likely to cause 'problems' for other people.
• Relocated beavers have a relatively high mortality rate, particularly if they are young or old.
• Beavers are very territorial. If beavers exist at the site of translocation, fighting will occur, with severe injuries or death as the result. Even if this is not the case, one group will be displaced and move to another location, thus starting the cycle of 'problems' all over again.

Here is a limited reference list for the problems of translocation:

1. McKinstry, Mark C. and Anderson, Stanley H. 2002. Survival, fates, and success of transplanted beavers, Castor canadensis, in Wyoming. The Canadian Field-Naturalist 116:60-68.

From 1994 to 1999 we trapped and relocated 234 Beaver to 14 areas throughout Wyoming to improve riparian habitat and create natural wetlands. We attached radio transmitters to 114 Beaver and subsequently determined movements and mortality of release Beaver...Mortality and emigration (including transmitter failure) accounted for the loss of 30% and 51%, respectively, of telemetered Beaver within 6 months of release. ...2-3.5 year-old Beaver had higher average success (measured in days of occupancy at the release site) than older animals. Animals < 2 years old had 100% mortality and emigration losses within 6 months of release.

2. Petro, Vanessa M. 2013. Evaluating "nuisance" beaver relocation as a tool to increase coho salmon habitat in the Alsea Basin of the central Oregon Coast Range.

I trapped and transported 38 individuals to the nine release sites where dams constructed by beavers would benefit coho salmon productivity. All adult and sub-adult beavers were equipped with tail-mount transmitters. ... All radio-tagged individuals dispersed from their release sites. Survival 16 weeks post-release was 47%. Twelve of the radio-tagged beavers died within 90 days of release. Three cause-specific sources of mortality were identified including predation, natural causes, and human related. Mountain lions (Puma concolor) were responsible for the majority of predation based mortalities. Of the 38 nuisance beavers relocated, only five individuals contributed to the nine dams constructed post-release.