BIOL 1902 Lecture Notes - Lecture 7: Northern Water Snake, Ruffed Grouse, Supercooling
28 Mar 2016
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Subnivean space: the crystalized zone of snow cover next to the ground & through which small animals move around in winter: ruffed grouse bed. Birds are endotherms: on cold nights black-capped chickadees lower their body core temperature by. 12 oc: entering a deep sleep called torpor, shivering is an important means of thermogenesis. Frost line: the level in the ground to which frost affects the ground: snakes survive by moving down below the frost line & becoming dormant, behaviour freeze avoidance, northern water snake leaving its hibernaculum. All adult & most hatchling turtles escape subzero temperatures by going to the bottom of ponds & lakes. American toads dig down beneath the frost line. Many insects survive winter above the frost line: adults die before they die, they mate & lay eggs, some survive winter as eggs ootheca (egg case) Either no water in the egg or antifreeze is used. Glycerol or sorbitol = cryoprotectants: walking sticks also overwinter as eggs.
