Winter Survival

 

                Transitioning from the abundance of summer’s bounty to the stark depths of winter’s chill, Mother Nature has equipped her creatures with various means of survival.   Migration, hibernation, adaptation – every creature, large or small, has a way to bide its time through the extremes of winter until spring returns with warmth, provisions and a new beginning.

Migration

            Shorter days and cooler nights trigger hormones that cue migratory birds to head south to winter breeding grounds where food is more abundant.  Many warblers,  grosbeaks, flycatchers, waterfowl, sparrows and shorebirds head south to destinations such as Texas, Mexico, South America, Central America and the Caribbean.   To prepare for the long flight, they must eat to bulk up, with some birds increasing fat stores by as much as 50 percent.  Many of these birds rest during the day and travel at night.  Hummingbirds winter in Central America, from Mexico to Panama.  These tiny birds fly by day but must cross the Gulf of Mexico without stopping.  This seems like an arduous trek until you consider the Arctic tern, which migrates from the Arctic to the Antarctic coast, a 40,000 to 50,000 mile trip.   

Hibernation

            In Virginia, woodchucks and black bears hibernate.  After bulking up in the fall, they sleep away the winter in a warm den, undergoing a decreased heart rate and body temperature.  Fat store keep them alive.  Bats hibernate in caves or trees.  Chipmunks are reported to hibernate but actually rely on food stored in their burrows so that can remain underground and inactive during winter. 

Adaptation

            Some animals adapt to cold weather by growing a thicker coat of fur and bulking up.  Others, such as squirrels, spend more time in the nest, coming out only to recover food supplies hoarded during warmer weather.  Opossums may sleep more and eat less, and may forage during the day instead of night to take advantage of warmer temperatures.  As omnivores, flexible eating habits enable raccoons to eat acorns, berries or any available food source during winter.  A thick winter coat and the ability to sleep for weeks in a warm den also help raccoons cope with winter weather. 

Reptiles

            Reptiles do not hibernate.  Brumation or torpor is the dormant state cold-blooded reptiles resort to in order to cope with cold weather.  Snakes may find a protected burrow or rocky area in which to sleep during winter, but they don’t rely on fat stores like animals that hibernate.  On an unseasonably warm day, a snake may wander out of hiding, warm up in the sun and catch a meal before returning to safety and  sleep. 

            Some frogs and toads find a winter home underground or beneath leaf litter or logs.  Here they sleep away the winter months in a dormant state with a very low metabolism.  Others lower their metabolism while remaining under water.  Water, rich in oxygen, provides them the oxygen they need to survive. 

Insects

            Honey bees cluster together to keep  warm in the hive.  Some adult insects, such as the praying mantis, die but their eggs survive and hatch in spring.  Bumble bee colonies die with the exception of a single fertile queen, who seeks shelter and overwinters in a dormant state until spring arrives and she can create a new colony.  Some butterflies, like many insects, find shelter in a woodpile or other crevice and enter diapauses, a suspended state of “sleep.”

Humans

            This species shows impressive adaptability at overwintering.  Some migrate to condos in Florida for the winter, traveling by day or night.  Others bulk up and become dormant with a steady diet of televised sports.  Some hibernate, consume quantities of hot chocolate and read gardening magazines and seed catalogs in preparation for spring’s arrival.