Thursday, January 23, 2014

Walking on water.

Walking on water is often a metaphor for an almost-impossible task, 
for breaking through personal limitations and achieving dramatic success. 
And today, on my way back from the deli, I saw the birds of Emdrup So walking on the water. 

However, the real extraordinary tasks they do, is swimming in the water just before it freezes up.

Every time I see a bird swimming along on the partially frozen lake or standing on ice, I wondered how its feet don’t freeze! Those feet are not thick enough to have an insulating layer of fat, nor are they covered in feathers.

So I did the research thing and googled:

Packed into those birds are physical and behavioral adaptations to keep them provisioned throughout the year.

While a few birds have feathers on their feet to help keep warm, many birds have naked feet. A counter-current blood exchange in the feet helps keep the heat loss to a minimum while preventing frostbite. A bird might also tuck one foot up under its feathers, balancing on only one leg!

In these birds, blood flow is carefully regulated to maintain the delicate balance of providing blood but maintaining core body temperature. While the core temperature of a duck or gull standing on ice may be 40 degrees C, its feet may be only slightly above freezing.