By Tom Koritansky, Director of Park Operations

Holding the title of North America’s largest rodent, the North American beaver is known for its tenacious work ethic and impressive building skills. Sometimes called “nature’s engineer,” no other animal can manipulate its habitat to suit its needs like the beaver.

As semi-aquatic mammals, beavers can be found in many slow-moving stream and wetland habitats throughout Ohio. Good sites for beavers to take up residence include areas by water with an abundance of vegetation including small trees and shrubs. Beavers are best known for their intricate and impressive dams built to hold water so that they have a safe place to build homed. These highly-adaptable animals are skillful enough to change their environment to make a more ideal living space. Within the deeper water held by the dam, beavers will construct lodges that will become their homes. Lodges are often surrounded by deep water to protect them from potential predators. Not all beavers build dams though—sometimes beavers living in very deep water will not feel the need to build one.

The dams and lodges built by beavers are made from mud, sticks and other plant debris. Their lodges are often constructed in the shape of domed with underwater entrances and floors lined with woodchips to keep the interior dry. Beaver dams average about three to five feet tall and range extensively in length. Many are 50 to 200 feet long, but there have also been some truly massive dams discovered. The largest dam known to exist in Ohio was found in Columbiana County and measured 1,200 feet long. The largest dam in the world was discovered in 2007 at Wood Buffalo National Park in Northern Alberta, Canada using satellite imagery. This dam measured nearly 2,800 feet long!

A beaver’s diet consists entirely of plants. During the summer months, beavers feast on a variety of aquatic plants like arrowhead, cattail, sedge, bulrush and waterlily. To sustain themselves through the long and cold winter months, beavers prepare an extensive cache of twigs and branches near the entrances to their lodges and rely on nutrients derived from the bark and cambium of these twigs and branches. Branches from trees such as willow, cottonwood, poplar, alder, aspen, birch and maple are favorites. Beavers constantly gnaw on wood to keep their teeth from getting too long, since they never stop growing! Many of the stumps left behind from beaver cuttings will re-sprout from adventitious buds. The re-sprouted stems will again become food and building materials for beavers once they grow large enough to harvest.

The ponds and wetlands created after a beaver constructs a dam attract and provide sanctuaries for many other mammals, fish, amphibians, birds and insects. Many of the wetlands found throughout northeast Ohio formed as a result of the tenacious activity of beavers. Beavers even help to maintain the level of Pete’s Pond at Pete’s Pond Preserve in Wickliffe. Beaver ponds and wetlands function so well as attractive wildlife habitats that many of the created wetlands in Lake Metroparks like those at Girdled Road Reservation, Concord Woods Nature Park and River Road Park model the type of habitat formed by the activity of beavers. Instead of a dam made of mud and sticks though, a compacted earthen dam is formed and a manufactured structure is installed to control the flow of water, allowing the pond to maintain water levels in these habitats.

Since beaver populations in Lake County have risen over the years and as they continue to make homes for themselves in the parks, Lake Metroparks has taken steps to prevent damage to ponds and wetlands that could occur if beavers clog water outlets and overflow structures. These measures have included regularly monitoring ponds and wetlands for beaver activity, enclosing outlets in fencing and deepening the surrounding area to make it harder for beavers to plug them, and wrapping trees with wire fencing to prevent them from being chewed. By taking steps to deter beavers from plugging water outlets and overflows, we are able to avoid impairments to dams from unchecked rising water and prevent flooding to unwanted areas surrounding ponds and wetlands. In doing so, we are able to maintain the longevity of ponds and wetlands that host a wide variety of wildlife for our residents and patrons to enjoy.