It’s midwinter in New Hampshire and the beaver ponds are iced up. Even the Merrimack River in Concord can be seen iced over.
Ice changes the landscape and opens up a whole new world. People are out ice fishing, skating, and even snowshoeing across places that are totally off-limits the rest of the year.
"On skates, the world you can explore expands,” says NH Audubon's Grace McCulloch, co-host of Something Wild. “You are gliding across wetlands and ponds that in summer are thick with cattails and water lilies."
Of course, test the ice before you go out and pay attention to where you are; just because it's thick in one place doesn’t mean it's safe across the whole pond.
Exploring a beaver pond on a winter walk or snowshoe or while skating takes people to the closest proximity to a beaver’s winter home - the “beaver lodge.”
"Some people say “beaver hut," says Forest Society's Dave Anderson, Something Wild co-host, "but that diminutive term may be better suited to the smaller version constructed by muskrats; a little mud and cattail reed structure above the ice."
Beaver lodges are in a whole different league. They’re incredibly well engineered.
In the fall, beavers gather branches and saplings and store them underwater near the lodge; a winter pantry of sorts.
"So while I'm skating above the ice, the beavers are below it, having supper," says McCulloch.
And ice doesn’t just change life for beavers.
Once a pond freezes, it becomes a highway for other wildlife. Tracks tell the story: bobcats and lynx checking out lodges, deer trotting straight across, and foxes and coyotes looking for a meal.
And while you can see those tracks in the snow, there’s also a whole world that humans are missing out on, because beavers rely heavily on chemical communication.
Castoreum
Along the edges of ponds, beavers carefully construct scent mounds, small piles of mud mixed with dry vegetation, that help waft their scent through the air. The beavers maintain these mounds by adding castoreum.
Beavers have two types of scent glands: castor sacs and anal glands.
The castor sacs produce castoreum, a yellowish-brown, musky fluid used for territorial marking and communication. The anal glands produce an oil that is rubbed onto the fur to make it water-repellent.
The scent mounds communicate information about the gender and reproductive status of the beavers in the colony, their health and fitness. An entire complex olfactory language!
Castoreum has had a long history with humans, too.
It has been used commercially as a natural food flavoring, and as an expensive perfume fixative.
"Think about that irony a bit," says Anderson. "Fashionable ladies dabbing beaver gland secretions on pulse points."
(Listen to this Outside/In episode for more on castoreum and natural food flavoring).
The castoreum is also the primary lure used by fur trappers to bait their traps, thus luring beavers to their doom by their own territorial and reproductive instincts. Trapping season is in winter, from the winter coats of fur-bearing mammals.
Much of the early wealth of colonial America, most famously the Astor family fortune, came from the fur trade, fueled by harvesting of Castor canadensis, the North American beaver. This keystone species was nearly wiped out between 1600 and 1850.
A frozen pond looks simple, flat, and quiet. But even in the coldest season, the landscape is still very much alive. Tracks above, messages along the edges, beavers moving below, and maybe, occasionally, the sound of skates.
Something Wild is a partnership between NH Audubon, the Forest Society, and NHPR.
