Connecting people with nature in Ontario's Mississippi Valley

The Beaver, nature’s great watershed engineer

Press Release
Mississippi Valley Field Naturalists
September 21, 2006

by Sheila Edwards

Michael Runtz brings to life the work of one of nature’s great engineers in the watershed – the Beaver

BeaverA large crowd gathered on Thursday the 14th for Mississippi Valley Field Naturalists (MVFN) September lecture. Michael Runtz was the keynote speaker for the first of a series of talks exploring the “Mississippi Valley Watershed”.

One sign of a great educator is when an audience doesn’t realize how much they are learning. In his presentation “Beaver Ponds in the Watershed”, Michael Runtz showed he is one such educator. His enthusiastic delivery style brought to life information based on his astute observations of nature. A well respected naturalist, nature photographer, and author, Runtz captivated his audience with stories about beavers, the topic of his next natural history book. Based on the response Thursday, it should prove as popular as his other Canadian best-sellers such as Wild Wings, Algonquin Seasons and Moose Country .

Runtz showed us how beavers play the role of engineer when it comes to creating nutrient rich ponds, teeming with life. Water levels are raised, new species are attracted, and the forest gradually acquires a pond, marsh, and ribbon of grassland. The habitats thus created by this impressive rodent are vital to the health of our watershed.

As the seasons change, a beaver pond changes as well. In the spring, nutrients will be washed out, enriching the water downstream; frogs will be at their noisiest, many birds will be arriving to nest in the forest and on dead trees standing in the pond; and the beavers will be busy feeding and working on their dams and lodges. Beavers feed on tree bark, the soft layer under the bark, and also herbaceous plants like pond lilies. As fall approaches, the beaver becomes more visible during the day as it works on creating a food pile for the winter and does fall maintenance on its structures; the lodge’s insulation is upgraded by piling more mud on top and the dam must be high enough to ensure the pond does not completely freeze. The lodge’s exits are about 1.5 m below the water’s surface, at a depth which hopefully will remain unfrozen throughout the winter. The beaver swims underwater to the food pile, eating the branches that are weighed down by less edible wood like alder. Beavers keep the lodge’s upper chamber clean for sleeping by eating and defecating in the lower chamber. Like the rabbit, the beaver has a ‘two-pass’ digestive system to maximize the nutritional benefit of its high-roughage diet.

If you are interested in observing beavers, Runtz had some good suggestions. For the paddler, beaver can stay underwater for as long as 15 minutes, so if they startle and dive down, they could be gone a long time. For the XC-skier, if the hole at the top of the lodge is open, and surrounded by frost; the occupants are alive and well. When watching a beaver cutting wood, they may use their tail as a stool by leaning back on it; they will also use either their front teeth or side teeth depending on whether they are eating or cutting respectively.

On Thursday October 19th, MVFN welcomes guest speaker Aquatic Ecologist, Brian Potter (OMNR) who will discuss “Wetland Habitats in the Watershed” (7:30 p.m. Almonte United Church, 106 Elgin Street). For more information on the lecture series please contact Program Chair Joyce Clinton at 613-257-4879/email , or visit our website at www.mvfn.ca . For those interested in an MVFN nature walk, the next one will be hosted and led by Joel Byrne at his property “Big Creek” near Watsons Corners, Sunday October 15th. If interested, and for more information, please contact Mike McPhail at 613-256-7211 or email