While it's always fun to come across
any indication of a beaver's presence in the landscape, without a doubt
seeing one of these amazing creatures in the wild is much more exciting! Here in California's Central Valley, I've found those sightings to be rather rare - and therefore all the more special when they do occur. While I regularly come across
signs of beaver activity, such as felled trees, gnawed branches, dams, lodges and tracks, it's less frequent that I get to spend time watching these critters go about their daily business. So, when I came across this beaver on a small reservoir in the foothills, I savored the experience. Any moment with a beaver is an excellent opportunity to sit quietly beside the pond, watch and learn!
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| American Beaver in a small reservoir in the foothills of the Sierra |
Beavers are best known for their sturdy dams, which they construct of logs, sticks and mud. These dams are placed across streams and other areas of flowing water and are effective at slowing the flow of water to the point of flooding the area behind the dam. The resulting ponds provide a measure of safety from predators for the beavers, and the perfect place to build their lodges. These beaver-engineered ponds also develop into ideal habitat for beavers' preferred food to grow: streamside trees and shrubs, like willows, and aquatic plants. This type of habitat modification behavior is exhibited by very few other mammals.
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| Beaver dam in the Central Valley |
In these calm, carefully engineered ponds, beavers build their lodges. These are the beaver family's living quarters, dome-shaped structures with underwater entrances and multiple chambers inside in which they sleep and raise their young. As American Beavers are mostly nocturnal, they typically spend most of the daylight hours tucked away inside these lodges. They also serve as winter shelter in parts of the beaver's range that experience severe weather.
As beaver ponds and the surrounding wet meadows expand, these precious microhabitats become thriving ecosystems, benefiting a myriad of species and teeming with wildlife.
Fish and frogs spawn and grow in the ponds' quiet waters; waterfowl nest in emergent vegetation and herons stalk along the margins; racoons and other nocturnal mammals visit the ponds to drink and hunt; and in many parts of the U.S. (though not in California) moose feed on the aquatic vegetation that thrives in the shallow, calm waters of beaver ponds.
Beaver ponds are one of the best (and often most beautiful and peaceful) habitats in which to sit quietly watching for many types of wildlife.
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| An idyllic beaver pond and lodge in Wyoming's Grand Teton National Park |
In the absence of a suitable lodge site, where river banks are steep and the water is too deep or swift for the construction of a traditional lodge, beavers will construct earthen dens or burrows by tunneling into the bank. Like traditional lodges, the entrances to these bank burrows are underwater.
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| Beaver bank burrow, topped with a small bank lodge. |
One such abandoned bank burrow I found, pictured above, was also fortified with logs and sticks. The entrance was originally underwater, and the falling water levels that exposed it probably contributed to this beaver den being abandoned.
Beavers live in family groups, called colonies, of between two and eight individuals. These include a breeding pair, plus both the current and previous years' offspring. When beavers reach about two years in age, they leave their colony's territory to seek out suitable habitat in which to establish a colony of their own.
My guess is that the beaver that created the bank burrow pictured below was moving into new territory, took up temporary residence in this small reservoir, but failed to establish a colony and so eventually moved on. An adult beaver in search of his own territory may travel five miles or more before finding suitable habitat.
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| Entrance to an abandoned bank burrow |
As largely aquatic mammals, beavers depend on the presence of water for their survival. But while we may picture these mammalian lumberjacks as denizens of idyllic forested ponds, in the Central Valley, beavers make do with irrigation ditches, managed wetlands and reservoirs, in addition to rivers and streams.
Trees are another crucial component of their habitat, and they have a marked preference for willow, poplar and aspen. Not only are these used in the construction of their dams and lodges, but the leaves, shoots, twigs, bark and cambium make up a large portion of their diet. Beavers feed on a wide range of herbaceous plant material as well, particularly the grasses, sedges, water lilies, cattails and ferns that grow so abundantly along the shallow margins of their ponds.
The American Beaver is found across most of North America, including Alaska and Canada, where suitable habitat exists; it is absent from southern Florida and the desert southwest. In California, beavers were hunted nearly to extinction by the early 1900's. They have since made a comeback, and have been reintroduced to many parts of their former range.
Perhaps unsurprisingly (though unfortunately), American Beavers, the largest species of rodent in North America, are considered by some to be pests. Their industrious and efficient damming and burrowing behavior can damage levees and plug culverts, resulting in unwanted flooding. At times, they are simply too good at what they do! But there are ways of mitigating beaver damage and learning to live peacefully alongside these amazing ecosystem engineers.
The beavers in the landscape do far more good than harm, and the many ecological benefits that beavers and their ponds provide are beginning to be more widely accepted.
Not only do beaver ponds create rich habitat for a host of other species, they also serve to retain water, slowing its movement through the landscape and allowing it to soak slowly back into the ground, replenishing aquifers, rather than rapidly running downstream. Streams with beaver activity along them are more likely to continue running year-round, rather than drying up during the summer months. And the ponds and wet meadows created by beavers are extremely beneficial in the face of wildfires, as they create natural firebreaks that slow or even stop the spread of fires.
It should be easy to see how all of the ecosystem services rendered by beavers are especially important in the arid, drought-prone western U.S. Hopefully now we have entered a new era in wildlife conservation, and can appreciate the roles of amazing animals like the American Beaver.
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| Characteristic tail slap behavior as a beaver dives for cover; often this is all you will get to see (or hear) of a beaver! |
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