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Chewed Beaver Stump. Photo Credit: Kurt Moser.
If you
hang around the stream, you may notice shady evidence of lumberjacks harvesting
wood along its banks. Entire trees are toppled over or encircled with telltale
chunks missing from their midsections. Sharpened stumps dot the landscape like
giant pencils shoved eraser-first into the ground.
But what appear to be signs of human axes at work are traces of a mammal that has inhabited Virginia for millions of years – the North American beaver (Castor canadensis). Despite beaver hunting by Native Americans followed by intensive trapping by European colonists for their pelts, beavers persist. But thanks to legal protection beginning in the late 19th century, beaver populations have rebounded from their extirpation in Virginia to today’s beaver presence in every VA county.
And
the engineering talents of beavers are shaping the habitats of Four-Mile-Run
stream. Peering over the red bridge just before the nature trail, you’ll see a
dam that beavers have been building this summer. It impounds water from Hume
Springs right before it reaches the run, creating a tranquil ponded area
for beaver homes. 
Beaver dam where Hume Spring meets Four-Mile-Run.
Photo Credit: Kurt Moser.
With their hard enameled front teeth (a feature of all
rodents), beavers harvest trees for materials to build dams and lodges. Glued
together with a combination of sticks, grasses, and mud, these sturdy structures
usually hold up well. Although heavy rains washed out the beaver’s dam in early
June, they have been gradually rebuilding it to maintain habitat for their domed
lodges.
A lodge is another engineering feat; one or more underwater entrances lead to a dry platform inside for sleeping and raising litters of 3-5 young per year. A beaver chooses a mate for life, co-parenting each offspring in the lodge for about two years before sending them off to start a colony of their own. Only if a mate dies will a beaver take up with a new partner.
Beaver caught in the act of gnawing bark off wood. Photo Credit: Todd Kiraly.
This time of year, newborn beaver kits are sheltered in the lodges while older siblings explore outside. Because beavers are nocturnal, you’ll be lucky to spot one in the daytime, but they occasionally cruise around at dawn or dusk feeding on plants and adding to their construction projects. If you suddenly hear a SMACK sound, it’s a beaver slapping its tail on the water to send an alarm signal to its family that danger – likely YOU – is lurking nearby.
In addition to using trees for building, beavers eat them.
They’re wholly herbivorous, feeding on leaves, bark, and twigs of riparian saplings
like aspen, willow, tulip poplar, and maple. A suite of adaptations equips beavers
for a stream lifestyle: ear and nose flaps to keep water out when swimming; webbed
hind feet for paddling; a rudder-like tail that stores fat; and a gland that
produces water repellant for their fur. And, if you hear whines, grunts, or
snuffles at dusk near Four-Mile Run, you may be listening to beavers chatting!
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Beaver eating stream vegetation. Photo Credit: Matt Strachan.
