http://www.wqed.org/birdblog/2008/01/21/coping-with-cold-anatomy/ A Bird Watcher's View of the World Thu, 20 Nov 2008 21:35:52 +0000 http://wordpress.org/?v=2.6.3 http://www.wqed.org/birdblog/2008/01/21/coping-with-cold-anatomy/#comment-380 Marjorie Vantassel Fri, 01 Feb 2008 05:48:59 +0000 http://www.wqed.org/birdblog/2008/01/21/coping-with-cold-anatomy/#comment-380 Thanks for that information. I live across from the Kiski River and it amazes me that the geese (we have anywhere from 30-80 who spend time in a farm field behind me, and wander up into the beginning of my back yard at times) look like they are just cruising/swimming upstream in between the chunks of ice or they sit on a huge pond that is 2/3 frozen some days. The pond is in an industrial park not far from me also. Now I know how they do it. Thanks for that information. I live across from the Kiski River and it amazes me that the geese (we have anywhere from 30-80 who spend time in a farm field behind me, and wander up into the beginning of my back yard at times) look like they are just cruising/swimming upstream in between the chunks of ice or they sit on a huge pond that is 2/3 frozen some days. The pond is in an industrial park not far from me also. Now I know how they do it.

]]> http://www.wqed.org/birdblog/2008/01/21/coping-with-cold-anatomy/#comment-284 Anthony H. Bledsoe Mon, 21 Jan 2008 19:00:03 +0000 http://www.wqed.org/birdblog/2008/01/21/coping-with-cold-anatomy/#comment-284 The unusual adaptation in the feet of many birds that experience cold weather actually operates as a counter-current exchange system, so that nearly all of the warmth in the descending blood is transferred to the ascending blood. It's just one of many examples of that highly efficient way of transferring from one fluid or gas to another. A second example in birds involves their lungs. Unlike mammals, which have bulk flow respiration, air in the lungs of birds actually passes over the gas exchange surfaces in only one direction, with the blood of the lungs passing in the other direction. This allows for nearly complete uptake of oxygen from the blood, and almost complete depletion of carbon dioxide from the blood. The unusual adaptation in the feet of many birds that experience cold weather actually operates as a counter-current exchange system, so that nearly all of the warmth in the descending blood is transferred to the ascending blood. It’s just one of many examples of that highly efficient way of transferring from one fluid or gas to another. A second example in birds involves their lungs. Unlike mammals, which have bulk flow respiration, air in the lungs of birds actually passes over the gas exchange surfaces in only one direction, with the blood of the lungs passing in the other direction. This allows for nearly complete uptake of oxygen from the blood, and almost complete depletion of carbon dioxide from the blood.

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