Monday, October 22, 2012

Balancing Beavers

     When beavers first showed up in our pond, we had mixed reactions. I thought it would be great to have nature’s engineers maintaining our pond water levels, adding to a balanced ecosystem. And hey, they are Canada’s national animal and pretty interesting. My husband’s reaction was less than enthusiastic. “Oh no,” he said. “They will take out the trees and cause all kinds of damage.” We were both right. For a while the busy beavers worked nightly to plug holes in the pond and raise the water level. But the destruction – plugging the overflow drain, dropping trees around the pond, even a large cedar at the fence line. Trees landed across fences, resulting in the escape of several sheep. There were simply too many trees in too large an area to save by wrapping with chicken wire. After a few years the parents turfed out the eldest children in their clan, at first by punching a hole in the pond to create a new neighbouring pond. This just succeeded in flooding the neighbour’s field. So the kids moved on to the golf course, and were seen late at night waddling down the road.
       Besides the damage we can all see, there is the microscopic damage caused by the organisms they carry. “Beaver fever” caused by Giardia is a common occurrence when beavers move their homes into open drinking water systems. This organism causes severe gastric distress and diarrhoea and is no laughing matter to those affected. One of my sons contracted Giardia from playing on a river bank when were in California. He had severe diarrhoea for a year, even after diagnosis and treatment. Beavers can also carry E. coli and Salmonella. Even though we do not drink from this pond, we worried that such organisms would affect our garden’s irrigation water which came from this pond. When the damage and health risk from beavers are weighed against their benefits, it may become necessary to remove the beavers permanently from a water body.
      The CRD enlisted the help of a licenced trapper, trained in the Malaspina College (now Vancouver Island University) Resource Management diploma program to remove the beavers from a water system on Saturna Island. Private property owners who use ponds as drinking water systems have also used the same trapper to successfully remove beavers. It is important that people have the proper training, permits and licenses in place when they attempt to remove beavers from an area.
      At one time beavers were found in most ponds and lakes in the Gulf Islands. In fact, they probably built most of the ponds years ago. They would build dams which would hold water, flooding the land behind the dam, creating a wetland area rich with life. The Hudson’s Bay Company had a base on San Juan Island and proceeded to trap all the beavers in the area for their pelts. In recent years, as farmers have been digging ponds for irrigation, developments building their own human-made dams for drinking water and predators (except for man) absent the stage is set for beaver numbers to increase. There is little interest in trapping them for their pelts these days, at least around these parts. Their introduction is believed to be via driftwood logs and log booms, but introduction by humans cannot be ruled out entirely.
      As beavers become re-established throughout the Gulf and San Juan Islands there will no doubt be conflicts between people who see only the cute Canadian symbol on the nickel, the master builders who engineer ecosystems that suit their needs and enhance wetlands, and those who are concerned about the health and safety risks and the unwanted damage and flooding that can occur. There will be a need to understand these animals and balance their presence, often called “the most destructive creatures next to man”.

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