Bison Napping Covered with Frost
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For hours these bison had been quietly lying on the warm ground next to Scalloped Spring.  Steam from the spring and from nearby Sawmill Geyser had completely coated their hair with frost.  Our first impulse is to think they must feel very cold, but actually this illustrates how well their hair is insulating them.  The heat from their bodies does not escape through their hair far enough to melt the frost, but notice their warm horns are bare.