Friday, March 9, 2012

Great Blue Heron on Ice

For the second time in the last few years, Great Blue Herons greeted me on the ice at Wells Lake in Rice County, Minnesota.This past Wednesday, 27 birds loafed on the ice. Why don't these birds get hypothermic? I have previously posted on counter current exchanges in birds. In the upper legs, many birds have networks of arteries and veins. The arteries bring warm blood from the bird's body. This warmth is captured by the cool veins flowing back from the bird's extremities. These heat exchanges can be very efficient, leaving relatively little heat to be lost to the ice.

The second heron photograph was not taken on the ice at Wells Lake. Rather, this Florida bird had more sense to take on an early Minnesota spring!

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