A Toothily Tireless Engineer

The castor Canadensis, commonly known as the North American beaver, has increased its population in Saskatchewan, causing a great headache for some farmers and landowners. Due to the number of beavers culled, concern has arisen from both sides of what could be called the “beaver war.” There are those who see the beaver as a pest and those who see it as an integral part of the wetlands and ecosystem.

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The beaver is classified as a “keystone” species, meaning a great many other species depend on its activity for existence. The pond a beaver creates will encourage the creation of wetlands. In a wooded area, the beaver creates a clearing by felling trees. This opening in the canopy permits sunlight to reach the floor, which encourages life in the form of algae and small insects. This encourages small invertebrates that become a source of food for mammals, birds and larger aquatic creatures. As the beaver pond is becoming established, grasses and bushes are attracted to the perimeter, creating the beginnings of a wetland. The pond improves the water system of the area by acting like a sponge, storing runoff that is slowly released over dry periods. The algae and plants remove toxins such as fertilizers and pesticides from the water, acting as a natural purification system. The ponds also have the ability to recharge water aquifers, stabilize the water table, and better maintain stream flows during droughts.

These attributes have led beavers to be introduced to drought-stricken California in an attempt to attract water. Beavers will find even the smallest trickle of water and, to create a safe haven for themselves, will form a pond. These ponds then cause moisture to rise which then, if there is enough, attract rain. Dry atmosphere and desert repel moisture; wet atmosphere attracts moisture in the form of rain.

In Patagonia, South America, where the beaver population has exploded, landowners are facing problems due to the inept attempts at eradication since the 1940s. The forests of Patagonia have not fared well under the onslaught of the beaver and the vulnerability of the native trees has been proven as they fail to re-establish themselves once gnawed at or flooded. This has led to 50% of Tierra del Fuego’s riparian forests being damaged by beavers.

Given time, North American trees like aspen, birch and willow will rejuvenate, providing more building material for the beaver. Take the resource out of the area and the beaver will move on.

We naturally associate the beaver with dam-building. However, beavers will inhabit rivers and large streams that have deep enough water, and they will live in bank burrows if the noise of the water flow does not exceed 53 decibels. Once the water flow noise or depth changes, a beaver lodge or dam will be constructed to create deep water as protection from predators and also to quell water flow noise. The beaver will dam the noisiest part of a stream; it is akin to us installing sound-proofing to reduce traffic noise. Corrugated culverts are especially annoying to the beaver because of the sound the water makes as it runs over the ribbed metal.

Beavers are territorial and unless the population is totally eradicated, new beavers will move into old or disused ponds and lodges. However, they won’t use the old dam. They will build a new dam, felling more trees and creating a larger pond in the process. In Patagonia, if the authorities had understood the life cycle of the beaver and its traits back in the ’40s and ’50s, the eradication attempts may have been radically different from the failed attempts of the past.

In certain areas, scientists and animal groups have found ways for the beaver to coexist with the landowner. In one experiment, it was noticed that the beavers did not keep increasing the height of their dam once it reached a certain height. They were content with a certain water level and would only change the height of the dam if changes in the water level occurred with the onset of rain, and if the water flow noise was above 55 decibels — when the water rose and ran over the top of the dam. But once the dam reached a certain height and the noise of the overflow was 51 decibels, the beaver seemed to tolerate it and built no higher.

Installed on this particular pond was a pond-leveler, a pipe that took excess water downstream to a place where the sound of rushing water could not be heard by the beavers. The animals showed no signs of further damming or enlarging their pond. It seemed they were content with the size and quality of their habitat. Over a period of time the beavers produced only two or three kits per year. These stayed for about two years before leaving to find new pastures. This experiment and final solution to the plight of the landowner and beaver pollution were in Mission, B.C. Landowner and beaver now live in harmony.

In another experiment, speakers were placed on the bank of a canal in Illinois, where most beavers live in bank burrows. The speakers emitted the sound of rushing water at 76 decibels. Overnight the beavers completely buried the speakers in mud and timber, but no dam was built!

Other controls that can be used to prevent beavers from coming onto and inhabiting property are to cover trees and put flow devices into streams. These devices prevent the beaver from being able to dam the river or stream. The flow control is a five-sided shape that sits in the stream. Its design works against the engineering skills of the beaver, to the extent that the beaver moves on in frustration.

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A wildlife conflict manager spent three hours building this device, which will prevent damming and last for years. The angles of the fence’s construction prevent the beaver from stopping the flow of water. -Photo courtesy TheFurBearers.com

Experimentation is the key. According to beaver-removal specialists, what works in one stream in one area may not necessarily work in another.

Both Ontario and B.C. have taken on this new approach to working with the beaver and controlling it in this unique way. But, and this is a big but, Saskatchewan does not have the same topography and where the beaver has inhabited is already considered wetlands.  What the beaver is doing in Saskatchewan could be construed as increasing the size of the wetlands. Many landowners and farmers have, over the years, spent time and money on removing the creatures on a nearly annual basis, to the extent that in 2014 a total of 37,645 beaver tails were turned in, a 56% increase in one year from the 2013 count.

One landowner east of Wadena says that the beaver population has increased over the years and the annual problem of eradication takes valuable time and resource away from the farm.  Local RMs are spending more and more time unblocking culverts and removing dams, only for the eager beavers immediately to block up the culvert again or to reconstruct a new dam, all in an attempt to quiet the noise of rushing water.

Because of the damage beavers do and the growing understanding of how the beaver can complement the environment, specialized groups have become more prolific and now focus on resolving human/beaver conflict. Many companies will design and create solutions so that the landowner and beaver can live in relative harmony.

The Wadena News contacted a Vancouver-based company, whose spokesperson said, “We are aware that Saskatchewan is keeping Canada alive with the food that is produced, and that has to take precedence over beaver welfare.” They also indicated they would like to be able to show what they can do to positively influence the farmer/beaver conflict. As yet they have not been contacted for help by any landowner in Saskatchewan who is willing to experiment so that a long-lasting solution to beaver-related flooding problems can be effected.

Whichever way one looks at this problem, a solution needs to be found, as land that is lost is a drawback for the farmer and a blow to the capacity for food production. It is obvious that failed attempts to limit the damage from beaver behaviour has led to an environmental problem for the authorities in Patagonia. It is only a matter of time before this problem becomes an even more expensive one in Saskatchewan.

By Andy Labdon

















Wadena News


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