Why a duck’s feet don’t freeze in winter and other chilly questions

2021-12-23 07:42:34 By : Mr. TONY CHEN

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We were driving across the Mount Desert Island causeway the other day when I spotted a group of ducks bobbing in the ocean waves. Flashes of white had me guessing that they were either buffleheads or eiders, both common off the coast of Maine. But the birds were too far away for me to positively identify them, and in just a few seconds, we’d left the water behind.

The brief wildlife spotting got me thinking — about multiple things.

First of all, it reminded me of the opportunities to spot birds along the Maine coast during the winter. At a time when many other animals are lying low, a variety of birds can be found spending Maine’s coldest months in saltwater.

Throughout the season, I often visit public docks to find loons mingling with a variety of gulls and ducks.

Loons can be tough to spot in the winter. In the summer, they display striking patterns of white, black and iridescent feathers that include stripes and polka dots. In the winter, their plumage shifts to a muted wash of gray and white. Though they still have those red eyes and distinctive dagger-like bills.

The reason so many loons are spotted along Maine’s coast in the winter is simple: the lakes and ponds where they nest and fish in the summer are frozen over.

For the same reason, ducks such as common goldeneyes and mallards move to coastal waters in the winter. Although you can also find ducks in any open freshwater, despite it being terribly cold out.

All of these thoughts sparked more thoughts — and questions.

“How do you think ducks’ feet keep from freezing?” I asked my husband Derek as we continued to drive away from the ocean. “The water must be so cold.”

Derek had no idea, not even a guess. Neither did I.

I’ve pondered similar questions before. In fact, back in 2013, I wrote a story for the Bangor Daily News about how different animals weather Maine’s harsh winters. For the story, I interviewed biologists about how different mammals burrow under the snow and hibernate. I also explored how frogs can essentially freeze, but not perish. But for that particular story, I didn’t go into depth about birds.

So when we arrived back home, I decided to do a little online research. As it turns out, I’m not the first person to observe a duck swimming through frigid water and wonder: Aren’t their feet frozen?

The answer is more complex than I thought it’d be, and it differs from bird to bird. But I’ll dare to summarize.

A coldwater duck has special vein structures that exchange heat high up in the leg so that the blood that’s flowing down to the foot is fairly cold (and the blood flowing up into its body remains warm). That way, the foot doesn’t lose much heat when it comes into contact with cold water or ice. It simply doesn’t have the heat to lose.

In addition, bird legs and feet lack a lot of soft tissue and muscles that would require warm blood to function. In fact, the muscles that operate the foot are mostly located higher up in the leg, connected to the bones of the feet with long tendons.

There have been multiple studies conducted on the topic if you want to get into the nitty gritty of it, diagrams and all. But for me, the takeaway from all that I read is that animals are remarkable.

When I step outside on a freezing January evening and start shivering because my wool coat isn’t quite warm enough, I’ll think of all those ducks bobbing around in the ocean under the stars. I also think about the white-tailed deer settling down in the snow to sleep and the shrew curled up in its burrow.  

Throughout the winter, I enjoy seeking out some of these hardy animals to photograph from a respectful distance. But it can be a challenge.

The forest is often quiet, though I can usually spot a few birds such as hairy woodpeckers, chickadees, nuthatches and brown creepers. Tracks in the snow tell me that a lot more activity is happening than it seems.

But if I’m really determined to photograph an animal during the winter, I usually head to the coast. I suggest you do the same. See what you can spot out there on the waves.

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Aislinn Sarnacki is a Maine outdoors writer and the author of three Maine hiking guidebooks including “Family Friendly Hikes in Maine.” Find her on Twitter and Facebook @1minhikegirl. You can also... More by Aislinn Sarnacki