An adult beaver can cut down more than 400 trees per year for dam and lodge construction—and for food, as tree bark is the beaver’s primary diet. Their work is not just destructive, as their cutting down sections of forest near a pond actually opens the area for lush new growth of grasses, shrubs and young trees, thus increasing the food supply for wildlife that also benefit from the increased abundance of pond water. The beaver’s work renews and sustains the ecosystem. When the pond eventually fills with silt and plant debris, the beavers move on, having created a new meadow. Their old dams, hidden from sight by the overgrowth, cause water to be trapped under the new ground surface, which helps to protect the area from future drought.
Dr. Glynnis Hood has spent years studying and documenting the activities of beavers and their impact on landscape. Alberta’s Elk Island National Park was a perfect laboratory, providing 54 years of records on beaver populations and open water in times of rain surplus and drought. Her work, published in a book entitled, The Beaver Manifesto,documented the impact of the beaver in drought-proofing the ecosystem. She found that long-standing ponds and lakes with beavers had a staggering nine times more open water than ponds where beavers were not present, regardless of rainfall amounts. In 2002, Alberta had one of the worst droughts in its history. In Elk Island Park, the only places with much ponded water were those with beaver populations (p. 47).
Despite the good the beavers do, some still consider them a problem. Michel Leclair, manager of Gatineau Park in Quebec, for years tried to control beaver activity by dynamiting dams and killing beavers. Yet the efficient and industrious rodents would quickly rebuild, blocking culverts and flooding roads. So, as depicted in the Canadian Broadcasting Corporation documentary The Beaver Whisperer, Leclair decided to work with the beavers. Since the sound of moving water motivates them to build dams, he produced the sound of running water by placing posts in streams, directing the beavers to build in locations where he wanted a dam to be. Today, he runs an efficient water management system in a huge park—with hundreds of beavers serving as his willing, eager, non-union, unpaid civil servants! As Leclair describes in The Beaver Whisperer, the process of human dam-building—even for a small dam—requires expensive and time-consuming design, engineering reports, environmental assessments and construction contracts. Instead, Leclair coaxes the beavers to do the job for free in a matter of days, once he directs them to the work site.