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       Not all migratiions span the globe,however.Many species make short trips,sometimes only a few miles,to take advantage of local conditions known as microclimates.Elk in Colorado move from high country to nearby valleys.Bald eagles in Alaska seek open water.White-tailed deer in these Wisconsin woods search out a southfacing slope to catch the morning sun.
       Other creatures devise their own ways to deal with the harsh realities of winter.Musk ox stand with their backs to the belowzero wind,slowly breathing through nostrils that warm the supercooled arctic air before it is taken into the lungs.Polar bears stay warm by laying on layers of fat up to seven inches thick beneath a coat of fur with nearly10000hairs per square inch.Their rough footpads are skidresistant on the ice.
       The survival of some spevies seems nothing short of miraculous.The chickadee,for example,weighing just onethird of an ounce,seems a tiny spark of life to throw to the merey of frigid,40m.p.h.winds.
       To keep their intermal fumace stoked,chickadees eat twice as much food in winter as in summer.They feed almost constantly during daylight to accumu;ate a layer of fat that will burn slowly through the cold night.They also have 30-percent more feathers in the winter and can fluff them up,trapping a layer of warm air.
       When it gets very cold,chickadees lower themselves into a lind of controlled hypothermic state,dropping their body temperatures as much as 20 degrees below the normal 104,thereby slowing energy consumption.With any hint of warmth,chickadees emerge from their sheltered cavems of thick brush,chirping softly and eating.
       Many cold-blooded species bury themselves in the mud to avoid freezing,slowing themselves to near-death states.Wood frogs actually freeze solid,like lumps of ice,and thaw when Spring comes.The frog floods its bloodstream with glucose,a natural antifreeze prevents cell damage-a trick also used by garter snakes,insects and painted turtles.


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