Beavers and their Benefactors

By Todd Miller

After walking through a mile or more of second-growth woods, it was visually refreshing to see an opening ahead in the forest.  It coincided with the appearance of some bogwalks - logs hewn in half, flat side up, to provide a dry surface to walk across otherwise wet and squishy soil.  Beyond the wood line, a seeming monoculture of sedges, perhaps two feet tall with small patches of cattails, their fruit stalks jutting five feet upwards.  And over there, a third of the way across the dozens of acres of open water, a rounded, conical mound of bare branches.  This was not a glacially formed lake.  It had been a forest surrounding a stream, perhaps only a few feet wide.  But some years ago, from the complete lack of snags emerging from the water, perhaps, 30- 50 years ago, it became impounded, drowning the trees.  It probably looked like a swamp in its first few years, a forest with water instead of soil for a floor.  But this was not a cypress swamp.  The dead and dying trees were probably forest species, much like on the rest of the Hills to Sea Trail: hemlock, red spruce, balsam fir, white pine, yellow birch.  Since it was daytime, I knew there wasn’t any point to looking for the inhabitants of the lodge; they were fast asleep, on a wooden floor above the waterline, but below the protection of several feet of small trunks and large, twigless branches.  In the unusual event of a bear attempting to take apart the lodge from the top, the owners would simply take a breath, slip from their bedroom into the water below, and swim underwater to silently surface a hundred feet or two from the lodge.  There was simply no potential predator that could match its swimming ability.  Safe in the water, it might look on as the brute destroyed days of craftsmanship.  Nevertheless, building came effortlessly, and it would only be a matter of time before a new lodge would reappear. 

It was spring and somewhat chilly.  The surface of the water seemed otherwise uninhabited.  In June, July, and August, one would be able to spot turtles basking on some object at the water’s edge, and large dragonflies skimming above the water for low-flying insects. 

I continued on the trail, taking the “Scenic Route” of bogwalks through the water.   Later that afternoon, after reaching Route 7 and trucking it back towards the Tech Center, I heard a chorus of spring peepers: I was approaching the marshy interface of the beaver pond and the forest.  Stopping in early dusk to stare at the beaver lodge, I noticed a small Canada goose only a few feet away, floating on the surface.  Out of the corner of my eye, I saw some movement on the side of the lodge, a brown, furry animal, perhaps the size and shape of a housecat, creeping.  No doubt, this was the lodges owner: a beaver, not the somewhat chipmunk-squirrel sized muskrat that made its similarly shaped lodge by mounding herbaceous plants rather than the more sturdy wood of the beaver’s mound.  Three little pigs.  There was no creature other than humans that would make a lodge from bricks.

The beaver seemed completely unperturbed by the goose, who had approached within a few feet of the lodge, and even started climbing on it.  Another beaver emerged from the water, some 80 feet away.  I quickly struggled to get my phone out of my pocket, quietly for that quintessential photo of a beaver swimming, with its lodge in the midground.   How was it that the beaver knew not to be afraid of the goose?  Probably over hundred, if not thousands of years, it either learned or was instilled with knowledge that this large oval floating on the water with its arched neck was no threat.  I’d seen geese nesting on beaver lodges before and realized that this one, too, was probably nesting on the lodge, a safe distance from upland predators.  Not only was the goose benign, it could sound a raucous alarm that the beaver could understand if it saw any threat.  For that matter, the goose probably had hard-wired into it that the splash of a beaver tail on the water signaled potential danger nearby, and would get ready to take flight, if confirmed.  So, here was an unexpected example of mutualism: the beaver creates an island, its lodge for the geese to nest on and the geese provide and alarm system for the beaver.

The beaver took a dangerous forest, where it could only slowly scramble away from predators into a watery kingdom, where it could swim to feed, sleep surrounded by the safety of water, and easily transport food stores for the winter to an underwater cache.  How strange that these giant rodents reverted to a below-surface lifestyle for the winter months, swimming underwater to their caches to bring a tasty aspen or maple branch to their living room for a meal, then off to sleep in the bedroom until hunger would rouse them, and they’d repeat the routine.  While some other mammals hibernated — when I was a child, I thought hibernating or migrating was a way of avoiding the cold, but I later learned it was more a way to avoid starvation — the beaver had figured out how to both stay awake and eat through the frozen months.  Incredible!  We, too, have learned to alter our environment and survive frigid temperatures.  One difference though is our modern use of concrete building materials.  Unlike the beavers, who will dam up a stream in the forest flood it and over the years, eat the surrounding hardwoods to eventually abandon the area, and move to another undisturbed forest that they flood, leaving their old pond to succumb to succession over the course of hundreds or thousands of years, we permanently alter the landscape, be it with steel and concrete, chemical pollutants or nuclear radiation.  Maybe, just maybe, one day, we could live like the beaver, a keystone species that makes changes that are positive for our fellow travelers…