Friday, November 30, 2012

Why are the geese still here?!

By Jon Ranieri

Every winter I am here at Colgate I am dumbfounded by how long the geese stay here. They swim in the freezing lake, and waddle around on the ice when Taylor Lake has frozen over, constantly pooping on our sidewalks. Well, I wanted to look into how these geese don't get frostbite and die (even though I wish they did).

Geese are warm blooded, but they are generally fine in really cold temperatures because their feathers provide amazing insulation. They have also adapted similar 'shivering' mechanisms to keep their body temperature high. More shivering means higher metabolic rate, which, unfortunately means more eating... and pooping. Ok so fine, their core can stay warm, but what about those little feet? They have no insulation, but geese seem to not mind standing on the ice for hours at a time, staring down their next grass plot to attack.

Lets take a step back. Why do we get frostbite? Because our body determines that sending blood to our extremities (which are poorly insulated and COLD), is not worth the cooling effect that blood will have on our core. Since we need to maintain a high body temperature to carry out normal bodily functions, our body chooses life over fingers and toes.  

How do geese do it? They have something called countercurrent heat exchange. In their legs, geese have arteries and veins positioned very close to each other. Arteries bringing warm blood to the feet, and veins bringing cold blood to the heart. BUT, we are trying to avoid the whole cold blood to the heart part. SO, the cold blood from the feet is warmed by the warm blood going to the feet, so the returning blood is actually somewhat warmer, so the goose doesn't mind sending blood down there. And the warm blood going to the feet is cooled by the cold blood coming from the feet, but thats OK, because the feet are very exposed and are going to be cold anyway. Usually, geese feet are just above freezing, while the core is around 100 F. Its all thanks to thermo equilibrium that allows the geese to stand on ice and snow.
 

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