Wildlife: April 2004

Flooding of agricultural areas such as hayfields, pasture, pecan or oak bottoms by beavers (Castor canadensis) can cause serious economic impact to producers. In Oklahoma, the agricultural damage caused by beavers during 2002 was valued at $1,297,053 by Oklahoma Wildlife Services personnel. The remoteness of many agricultural production areas presents unique challenges. Drainage of beaver-created floodwater for a three- to four-week period during early growing season could substantially reduce the damage incurred.

Beavers are known to repair cut dams very quickly (usually overnight), thus the need for a method to allow continued drainage. Mesh devices on drain pipes are common — however, they usually require frequent cleaning and are easily dammed by beavers. Long, rectangular wooden pipes (three-log drain) have been installed in dams for many years to control water levels in beaver wetlands. These, and similar devices, are usually cumbersome and often expensive, and offer only temporary relief of floodwater. Lethal beaver control devices are often damaging to non-target species such as raccoon or river otter and can be labor intensive.

A cost-effective, easily portable barrier that prevents drainage cuts in beaver dams from being repaired could offer temporary relief from beaver-created floodwater. Preliminary indications are that an electrical wire barrier erected in an hourglass configuration is an effective barrier to beavers attempting to patch or rebuild dams severed for drawdown purposes.

Charged hourglass configuration of wire 1 inch above water surface maintains cut in dam.

Beaver (left side of frame) taking a flying leap after an “encounter” with the barrier.

During the spring of 2003 on the Noble Foundation Wildlife Unit, six discrete beaver colonies were identified and corresponding beaver dams suitable for implementing water draw downs were located. A 12-inch-wide cut was made in each beaver dam to a depth 2 to 3 inches below water level, which provided sufficient flow to attract beaver activity and draw down the water level. An hourglass configuration of "Maxishock" 14-gauge stranded wire was erected in the cut and initially positioned 1 inch above the water surface. Four 18-inch fiberglass rods positioned at the corners of the hourglass held the wire in place. New Zealand-style, mini-strip graze energizers were used to charge the wire and were mounted 3 feet above the water level on a stake. A 20-inch piece of 12-gauge-high tensile wire pressed deeply into the mud served as ground. The device maintained drainage for up to two weeks during the study. In other incidental usages of this device, drainage has been maintained up to four weeks.

Three different styles of D cell battery-powered mini chargers have been used in the study, and all were effective units for this purpose. These units range from $80 to $100 and can easily be transported in a backpack along with the fiberglass rods, 10 feet of stranded wire and a ground wire. A "potato fork" seems to be a suitable tool for making the initial beaver dam cut.

This device is an effective tool for maintaining "cuts" in beaver dams for drawdown purposes and should take its place among the arsenal of non-lethal beaver management tools. Because of the admirable tenacity and dogged persistence of this creature, however, in the overall scheme of things, I would advise, "If you have to put your money down . . . bet on the beaver."