The lack of snow and ice this year has encouraged more than the usual numbers of ducks and geese to overwinter. I recently found signs that ducks have been hanging out in the small pond on my own land in central PEI – unusual for this time of year.
Duck tracks are easily identified by their webbing, size, and inward-toed gait (Photo 1); those shown here are from a Mallard (Anas platyrhynchos). Canada Goose tracks are roughly twice as large. Some Gull tracks are within this size range but wouldn’t show the backward-pointing toe (called the hallux) that you can see here.
I followed these tracks and found a spot where the duck stopped to preen (Photo 2). Using its bill, this duck cleaned its feathers and re-aligned the tiny barbs on them that help with warmth, waterproofing, and flight. It also spread oil from its preen gland – located near the base of the tail – over its feathers to further help with waterproofing. Preening is essentially the avian version of a wash, comb out, and bit of Byrlcreem.
Feathers aren’t the only adaptation waterfowl have to protect them from winter weather. Their legs and feet have a remarkable circulatory system to prevent heat loss while in ice-cold water or snow. If you put your hand in ice water, it will feel very cold – painfully so – within minutes. That’s because the large difference in temperature between your warm hand and the cold water causes heat to be lost very quickly.
In waterfowl, arteries carrying warm blood out from the heart are intertwined with veins carrying cool blood back from the feet. This does two things: first, it cools the blood heading to the feet so the temperature difference between foot and environment is minimized. Less difference in temperature means slower heat loss and reduced risk of freezing. Second, the heat removed from the blood heading to the feet warms the blood returning to the heart. This helps the bird maintain its core temperature by not bringing that very cool blood on board.
So, while we warm-footed humans would be dangerously uncomfortable standing on ice or snow, cool-footed Ducks and Geese barely notice it. In freezing temperatures, only 5% of the body heat lost by a Mallards is through its feet. In very cold weather, you’ll see birds standing on one foot. This is done from time to time, both to prevent frostbite and to further reduce overall heat loss by limiting the surface area in contact with ice or snow.
Winter wildlife adaptations are another part of PEI untamed!
I found this so interesting . I love ducks and watch them all spring and summer out on the Lake here in Quebec.