January 26, 2008 Outdoor Column

As the Woods Edge boys pushed our cart through the store this past weekend, I heard one of my all-time favorite wintertime comments from a fellow shopper.

"Boy, it is sure cold outside, glad I'm not a duck standing out on the ice freezing my toes off!"

I cringed, but kept rolling the cart toward the cereal isle with one hand on the handle and the other over Older Son's mouth to squelch the words I knew were about to come out of his mouth.

"Dad, didn't you say duck's feet don't get cold, 'cause they have those 'circle veins' in their feet to keep them warm?" spouted Older Son as I removed my hand at a distance I deemed out of earshot.

It's true.

In fact, why wouldn't one want to be a duck — to be able to be outside in the dead of winter completely and utterly stark naked and not be the least bit cold?

And, for the record, ducks actually only have three 'toes' as their hind 'toe' is called a hallux.

The feet and legs of ducks are absolutely crucial to their capacity for thermoregulation. Thermoregulation is simply maintaining body temperature. Both cold-blooded animals (reptiles, amphibians) as well as warm-blooded animals like ducks, physiologically maintain their body temperature to adapt to the particular atmospheric conditions in which they live.

Cold-blooded animals' body temperatures may range near freeing to more than 100 degrees, while warm-blooded animals maintain a constant and relatively high core body temperature.

It is, actually, a very simple process by which ducks use "counter-current" circulation to warm their feet and legs:

1. Veins take blood away from the feet where it is recycled through the lungs and heart.

2. In the duck body's warm core, the blood is recharged with oxygen while being warmed to near 100 degrees.

3. Arteries return this warmed blood to the duck's legs and feet. In a duck's feet and legs, arteries and veins lay alongside each other so the warm, arterial blood radiates heat to the cooler blood in the veins, thus limiting heat loss in the duck's tootsies through this "counter-current."

This does not mean that a duck's legs and feet are a toasty 100 degrees like their core temperature, however. Some heat loss does occur when their extremities are exposed to sub-freezing temperatures - so a duck's feet may be closer to 40 degrees than 100 degrees. But, as long as the temperature in a duck's legs and feet does not drop below the freezing mark, they will incur no soft tissue damage.

Ducks also conserve heat through other methods, such as standing on one leg to reduce exposure and reducing blood flow to their legs and feet in very cold weather in order to keep heat loss to a minimum.

Drive by Lakeside Park in Pittsburg the next time Playter's Lake is iced-over and I almost guarantee a sighting of a handful of Canada geese balancing on one foot on their frigid arctic abode.

It is now 19 degrees Fahrenheit at Woods Edge. I think I will run outside barefooted to test how long my "non-counter-current" human feet can stand the frozen front lawn. Mrs. Woods Edge says I have "duck on the brain" half of the time, anyway.

I hope she doesn't lock the door.