Warm, lazy summer days give way to frosty autumn mornings.  Bull bison become aggressive in the fall rut.  A Plains Bison kicks up prairie dust as it rises from its wallow.  A yellow flash emerges from the haze and diverts your attention from the bison to a Western Meadowlark. Soon meadowlarks will migrate south to warmer climes.  Bison, on the other hand will remain and endure the bitter cold winter of the Prairies.