Monday, December 19, 2011

They're Back: Beaver along Cherry Creek!

American Wigeons dabbling in Cherry Creek

Walking a stretch of the Cherry Creek bike path lined with the naked willows of winter and the occasional cottonwood tree looming large, I heard the unmistakable sound of a child’s squeaky toy. Well, perhaps it was a dog’s squeak toy? I looked around for a shaggy canine sporting a well-worn rubber toy in his mouth but found none. Glancing further and looking into the stream, I saw the noise makers. There they were - a pair of adorable American Wigeons - complete with their unmistakable pale blue beak. Now, seeing a blue-beaked duck may not excite very many people but to me it is like finding a semi-precious jewel in the dirt. Something not expected on my daily sojourn. I am used to seeing the ubiquitous Mallard in the creek, a handsome duck indeed; yet when I see something other than the Mallards I tend to get excited. And then, not a minute later, I saw a different duck with a huge white cheek mark vivid against its otherwise dark head, a Common Goldeneye. Not that a casual observer can really see his “golden eye” from this distance but that is this duck’s name nonetheless.

These dabbling ducks were enjoying a glassy-surfaced little lake that had been created by twigs, branches, brush, and a felled tree that were slowing down the water flow of the creek. For a few weeks it was hard not to notice the chewed-up remains of tree trunks I had observed along the path, and I knew there could only be one animal doing the chewing. Indeed, it was the North American Beaver (Castor canadensis). This hard working animal had inhabited this creek on and off for centuries. Long ago, about the time that the historic Four Mile House (located a mile downstream) stood as a respite for Colorado immigrants, travelers, and Native Americans, they frequented Cherry Creek until trapping diminished their populations.  How lucky I was living in a city and seeing wildlife doing wildlife things right before my eyes not from a TV screen.
The hard work of the North American Beaver
Beavers are what is called a “keystone species,” which is a term given to an animal that alters an ecosystem in such a way that it paves the way for other species to exist in this environment. Like the keystone in antique arched doorway, if it is removed, the whole arch collapses in on itself. The beaver’s diligent dam building creates a wetlands environment that opens a door for other species to inhabit. While it is true that none of us want every cottonwood tree felled along the creek because of the negative impacts this would cause, nor do we desire flooding from the ponds onto private property. However, there are ways to mitigate the beaver’s behavior without destroying this amazing animal. Wouldn't it be interesting if both beaver and humans could both live in and enjoy this area?

Beaver tree sculpture?

For people to coexist with beaver there are several solutions that have been developed. Flexible pipe can be installed as “pond levelers”; these devises are simple (see "beaver solutions"). They allow a creek to continually flow through an opening in the beaver’s dam without completely restricting the water flow thus managing any flooding that is the goal of the beaver's dam. This is a win/win situation; it allows a portion of the beloved pond habitat to remain and the beaver's living quarters while minimizing damage. To protect important riparian area trees from being felled by the beaver, various cylindrical wire cages can be wrapped around the trunks to discourage this behavior. Both solutions are not expensive or difficult to apply.

An amazing feat of dam building

A recent success story of beavers living alongside human development occurred in Martinez, California.  After the town spent huge sums of money to restore a once channeled creek called Alhambra Creek, the waterway became not only more attractive to the human eye but also to a beaver family that quickly took up residence. The beaver started building dams along this nicely refurbished waterway and flooding certain locations. Soon, the beavers and their dams were slated for removal or extermination in October of 2007. An outcry throughout the community allowed for further investigation, research, and education to determine the best way to solve the situation. A community effort called “Worth a Dam” coalesced that saved the beavers along Alhambra Creek. Experts were brought in (Skip Lisle from Vermont) to install a flow device made from flexible pipe. Today the Alhambra Creek beavers, now known as the “Martinez Beavers,” are a large tourist attraction. Their antics are viewed from a town bridge to the delight of children and adults. It has made the locals proud and happy to live successfully with wildlife.

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