Duck footprints are one of the more whimsical images of winter on the water. In fact, I was so enchanted by them while walking with a friend that I dropped my handwarmer right out of my mitten and into the Androscoggin River.

If I were a duck, I wouldn’t need hand warmers or mittens because I’d be perfectly adapted to the cold. Imagine walking barefoot on the ice and then plopping into the water and swimming around prowling for food. All of those little trails on the surface of the ice told stories of these hearty ducks’ comings and goings.

There are myriad duck species native to Maine and, while I usually write about ocean life, I’m going to cheat a little and write about a mostly freshwater species this week. This seems fair given the interconnectedness of our rivers and coast, and the fact that they are also sometimes found in salty water. It is easy to be drawn to something rare to focus on, but this species is one of the most common — not just in Maine but worldwide. It is the mallard duck, Anas platyrhynchos.

Mallards are medium-sized ducks, with flat bills (“platy” means flat and “rhynchos” means bill), the males having distinctive iridescent green heads. They are considered dabbling ducks due to the way that they feed by tipping their tails up in the air and their bills down below the surface to eat a variety of insects and plants living in the water. Their ability to eat a variety of foods contributes to their prevalence. In addition, as part of their tippable body design, their legs are in the middle of their bodies, as opposed to diving ducks that have legs positioned farther back.

This means that mallards are easily able to walk on land — or ice. They also have impressively large wings that allow them to fly easily. This allows them to move from place to place to find the best habitats and resources.

Because of their adaptability and versatility, mallards are found all over the place. They are found widely in North America, Europe and Asia. In some parts of the world, these mallards are the same species we have in Maine and, in others, they have evolved into new species, but all of them trace their ancestry back to the mallard.

Closer in scale, mallards are found in the tiniest bits of marsh or seasonal pond, and sometimes have even been found in swimming pools or city parks. Mallards are the stars of the beloved children’s book, “Make Way for Ducklings,” where they take up residence in the Boston Public Gardens and where there are now statues reminding visitors of the story.

The thing that I find most impressive about mallards, though, is their ability to thrive in the cold — and to make those elegant footprints on the ice. Keeping a body’s core warm is less challenging, and mallards use a combination of body fat, insulating feathers and an extra high body temperature (106 degrees) for that purpose. To keep their less-insulated and more-exposed faces warm, they often tuck those into their body feathers, making them appear temporarily, oddly headless. It turns out that their feet don’t actually stay terribly warm, but instead that they have a unique system of blood flow that keeps them from resulting in the rest of their body freezing.

Instead of simply having the warm blood from the body travel down to the cold feet and the cold blood from the feet travel back to the body, the artery carrying warm blood is right next to the one with the cold blood, allowing it to transfer a bit of heat to it before it returns to the body, thus keeping the body from freezing.

I’m still a little bit sad that I dropped my hand warmer, but it was worth the pause to enjoy watching the ducks and to wonder more about how they were thriving out there on the ice in the winter.

Susan Olcott is the director of strategic partnerships at Maine Coast Fishermen’s Association.

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