Winter wetlands: what's happening under the ice?

Compared to the thrum of a thriving summer wetland, winter wetlands may seem as silent as outer space.

But they're not empty, nor are they vacant – life's just a little slower, a little less showy, in an ice-covered marsh or swamp.

Mahogany multi-use pathway, Manotick
A beaver on its lodge in winter.

Mammals are still out and about: look closely and you'll likely spot deer, rabbit or coyote tracks in the snow, especially if there's some open water. 

Beavers have been known to be active at night to repair their lodges and habitat, and weasels are often out looking for a meal.

Great Gray Owls hunt all winter long.

Birds can also be abundant – more than you might expect. Chickadees, cardinals and blue jays will hang out in nearby trees and shrubs. Rafters of turkeys will wander the open fields. Mallards and other ducks will spend the winter if there's open water. Even owls will wait patiently in nearby trees for dinner to scurry across the ice.

And if you don't see an owl in the flesh, you might still find evidence of their efforts.

"If you really look, you could see wing prints in the snow of owls swooping down and capturing prey," said RVCA aquatic biologist Jennifer Lamoureux.

During hibernation, snapping turtles take in oxygen through their butts.

But beneath the ice, the wetland is sleepy. Water is barely flowing and underwater plants aren't generating much oxygen.

"The plants go dormant, and they are a driver of photosynthesis, so oxygen levels can be quite low," Lamoureux said.

Frogs, turtles and fish slow their heartrates and drop their body temperatures to compensate.

Some frogs will nestle into the muck to keep warm all winter, while fish move to deeper pools and reduce their feeding habits.

Turtles are another story. Some, like Blandings and snapping turtles, settle at the bottom and take in oxygen through the most unlikely of places: their butts. The musk turtle takes a different approach, using nodes on its tongue to absorb the little oxygen it needs. 

These aren't weather-proof plans, though. In extreme cold, not everyone survives, Lamoureux said.

"Oxygen is in high demand, so you can see a winter kill if the ice gets too thick and we have a prolonged cold winter," she said.

More extreme, frequent and prolonged freeze-thaw cycles can impact fish and wildlife population, too – and they might not make it through the hibernation period.

"Climate change is definitely disrupting some of these hibernation patterns," Lamoureux said.

Stoney Creek wetland restoration, Kanata

So if you're looking for a winter walk, don't discount your local wetland trail. It may look like a lunar landscape from a distance, but up close it's as alive as any of us can hope to be in the depths of winter.

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Wednesday, 12 May 2021

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