© 2007 Donna L. Watkins - Song Sparrow on Winter Morning
Have you ever wondered why it is that ducks can spend all day in near-freezing water and it doesn’t seem to bother them?For that matter, birds never seem to be bothered about cold feet. If we ran around in the ice and snow with bare feet, it wouldn’t be very long before we had a good case of frostbite. So why don’t birds need socks?
Birds have a network of arteries that take the blood down to their feet. These arteries are interwoven with the veins that return the blood from the feet. This network of arteries and veins is called a “wonder net.” The blood going down the arteries is hot at 106 degrees but the temperature of the blood returning in the veins may be as cool as 37 degrees as it leaves the foot. The warm blood reheats the cold blood coming from the foot before it enters the body.
The result is that the bird loses very little body heat, and the blood going into the foot never becomes dangerously cold in normal winter weather.
Source: Creation Moments
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