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Across the vast continent of North America temperatures have plummeted.  As I write this, sub-zero winds sweep across the Great Plains. Buffalo is seemingly gone–buried beneath uncounted tons of lake-effect snow.  Obviously, with all of this November cold, Americans are obsessed with one question:  what happens to snakes in the winter?

This seems somehow wrong.

This seems somehow wrong.

Snakes live in places that get very cold during the winter, yet the poor reptiles are cold-blooded and can’t be slithering around in snow and ice.  In fact, considering that their bodies become the same temperature as their surroundings, how do they avoid becoming snakecicles?  What happens to them when the mercury dips?

Technically speaking, snakes (and other reptiles & amphibians who live in climes which turn cold) do not hibernate—they brumate.   Brumation is a different sort of metabolic dormancy than mammalian hibernation, but there are many similarities. When reptiles go dormant, their breathing and heart rate drop to almost nil.  Brumating reptiles do not eat (or produce waste)—though they wake up occasionally from their dormancy to drink water.

Garter Snakes dormant in a hibernaculum

Garter Snakes dormant in a hibernaculum

As temperatures dip in autumn, temperate reptiles get all Roman and they seek out a hibernaculum—a sheltered environment which protects them throughout the winter. Hibernaculums are usually deep within the ground in holes, crevices, and burrows which reach beneath the frost line.  Certain species of snakes brumate together to share trace warmth.  Just imagine a colony of hundreds of little garter snakes in suspended animation beneath a snow covered rock wall in that picturesque New England snowscape!

Wait, where are the snakes?

Wait, where are the snakes?

Although it is not exactly the topic of this post, amphibians and aquatic reptiles also brumate—sometimes underwater or deep within the wet mud at the very bottom of ponds and lakes! The turtles, frogs, and newts take in sufficient oxygen through their skin to stay alive in their deeply reduced metabolic state—although they occasionally wake up from their torpor and swim about. An indelible memory of my childhood is seeing some little newt swimming beneath the ice of the frozen cranberry bog which I was standing on!

When spring comes and temperatures become warm enough, the snakes depart from their underground dens and sun themselves until they have sufficient energy to become active. Of course some reptiles live in such wintry locations that they have very little summer.  There are snakes (like northern rattlesnakes) which brumate 8 months out of the year!  Scientists believe that this prolonged dormancy allows the snakes to live longer—like an automobile turned off in a safe garage.

Garter snakes awaken en masse in the spring

Garter snakes awaken en masse in the spring

Timber Rattlesnake (Crotalus horridus)

The magnificent timber rattlesnake (Crotalus horridus) is a venomous pit viper which lives throughout the populated northeastern portion of the United States of America from Texas to New England.  Ferrebeekeeper has considerable affection for the dangerous reptile (at an appropriate distance, of course!) and has already referenced the timber rattler as a metaphor for national liberty and, strangely, as a point of comparison for a large sports venue.  But timber rattlesnakes are so much more.  They were one of the first new world animals to utterly fascinate and horrify European colonizers. In the colonial period a serious rattlesnake bite was a death sentence (although we now have anti-venom) but the original natural scientists did not appreciate how complicated and remarkable the snakes were in other aspects.

As I write this, it is November and the rattlesnakes are all abed for the winter.  Because they live in areas with harsh winters, timber rattlesnakes spend more than 7 months a year in hibernation.  Large numbers will nest together in a community den—sometimes together with other snakes such as blacksnakes and copperheads.  The den is usually a rocky chasm which extends deep beneath the frost line, and rattlesnakes may travel many miles to reach their hibernation den (a bi-annual journey which puts the snakes at great risk from predators and from cars).

Because of their large and diverse territory, timber rattlesnakes come in different sizes, colorations, and even have different venom types.  The average timber rattlesnake grows to 100 cm (39 in) long and weighs between a half kilo and a kilogram (1 to 2 pounds).  Much larger specimens are known (although there is considerable ridiculous dispute about the upper ranges of rattlesnake size).  Female timer rattlesnakes are viviparous although, unlike mammals, rattelsankes protect their eggs within their bodies until they hatch.  Rattlesnakes give birth to litters of 6-10 fully formed, fully poisonous little baby snakes, but they can only reproduce every few years since the experience is very hard on them.

Like catfishes, timber rattlesnakes have senses which we do not possess.  Pit vipers are so named because they have nostril like spots (pits!) on the side of the head which they use to perceive infrared electromagnetic radiation. These pits are quite sensitive and act as third eyes.  Snakes (and many other animals) also have special auxiliary olfactory sense organs called Jacobson’s organs which are extremely sensitive to various smells/tastes.  Snakes characteristically pick up chemical traces with their tongues and waft these smells before their Jacobson’s organs in the characteristic tongue-flicking which is such a trademark.

Of course rattlesnakes are not just sensitive—they are also expressive.  Among all other snakes they are distinctive in that they have a specialized structure at the end of their tail for making a warning noise. Rattlesnake rattles consists of hollow button-like segments which produce a distinctive buzzing when the snakes vibrate their tails.  As a rattlesnake sheds her skin (every few months), she adds a new button to her tail.  Rattles however are not perfect records of how many times snakes have shed their skin—sometimes buttons get knocked off, or just become brittle and fall away.  The rattle has a high frequency and varies in loudness between 60-80 decibels from a distance of one meter (which falls somewhere between the noise level of an animated conversation and a garbage disposal).  Ironically, the rattlesnakes themselves are deaf.

Timber Rattlesnakes can be masters of camouflage

The venom of timber rattlesnakes varies in toxicity depending on the subspecies, but the most toxic rattlesnakes are extremely venomous.  Type A venom is a neurotoxin whereas type B venom is hemorrhagic and proteolytic (which is to say it causes bleeding and breaks down fundamental body proteins).  Type C venom is largely harmless.  In Arkansas and Louisiana, timeber rattlesnakes are particularly dangerous because cross-breeding has resulted in snakes which have type AB venom (yikes!). To a lesser extent rattlesnake venom also contains esoteric myotoxins which rapidly kill muscle tissues.  This deadly cocktail of different venoms is of great interest to pharmacologists who continue to study the various toxic proteins to tease out potential medicines.

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Fortunately timber rattlesnakes are good-natured and do not generally bite without much posturing, rattling, hissing, and feinting.  They keep their retractable fangs folded up in a mouth sheath when not in use and they are capable of varying the amount of venom they inject based on how they are feeling.  It is best not to antagonize rattlesnakes lest they abandon their amiable disposition.

Timber rattlesnakes are gifted ambush predators which particularly prey on small mammals such as squirrels, chipmunks, mice, and other rodents, but they also eat amphibians and birds.  In turn rattlesnakes  are preyed on by owls, hawks, bobcats, foxes, crows, skunks, and even turkeys! Rattlesnakes are an important part of the woodland ecosystem, but they face serious threats from habitat loss and traffic (cars being indifferent to the protective poison of snakes).

C. horridus eating a chipmunk by unhinging its jaw (Photo taken by Kevin Ostanek)

Not only are many rattlesnakes killed by traffic, they must also face persecution. Many are killed by angry villagers carrying torches and pitchforks.  Gawping Texans take this to a particular extreme and organize great “rattlesnake round-ups” where huge numbers of rattlesnakes are wantonly tormented and killed for no particular reason (except perhaps to demonstrate a hatred of the world and its creatures).  This is particularly sad since rattlesnakes, like whales, or elephants (or ourselves) are k-selected animals.  They live long but reproduce slowly, which makes them especially vulnerable to population crashes.

If, by some appalling circumstance, you have read this far while a timber rattlesnake sits nearby buzzing its tail, you should run away from the snake!  Do not attempt to molest it.  If you feel threatened, call animal control.  The timber rattlesnake is already vanishing from great expanses of its territory.  It would be a shame if this beautiful and fearsome serpent were to slip away from the earth.

Timber Rattlesnake by Hazel Galloway

The Groundhog, Marmota monax (photo by Bill Smith)

Happy Groundhog Day!  Preliminary reports coming in seem to indicate that the nation’s most eminent groundhog oracles are not seeing their shadows today (what with the continent bestriding blizzard and all).  Oddly, this is interpreted as a sign that spring will arrive early this year.  However I tend to think those groundhogs on TV are media personalities who have forgotten their rural roots.  When I lived on a farm, the concept behind the holiday was more straightforward:  if you saw an actual groundhog on Groundhog Day, then winter might indeed end early, but if you didn’t (and I never did) winter would not be over for six more weeks.  Today most non-celebrity groundhogs did not stir from their deep hibernation chambers.  We probably still have plenty of winter left.

Groundhog Day is observed on or around Candelmas, which ostensibly celebrates the presentation of Baby Jesus to the temple:   Mary and Joseph took Jesus to the Kohens & Levites to perform the redemption of the firstborn and ceremonially purchase their firstborn son’s life back from the priests (I’m not sure Jesus ever really escaped the priesthood or the temple of Solomon so maybe his parents should have gotten their money back–but that’s a different story).  Candelmas was elided with pre-Christian holidays involving the prediction of the weather by animal augury.  The holiday’s roots in America are from the Pennsylvania Germans.  Apparently in pagan Germany, the original animal weather prophets were badgers or bears.  Imagine how exciting this holiday would be if we stuffed our pompous civic officials together with a disgruntled bear who had just been prodded awake from hibernation so people could take flash photographs!

At any rate we have gotten rather far afield of the day’s celebrated weather oracle, the groundhog or woodchuck (Marmota monax) which is actually a rodent of the marmot family, Sciuridae. Marmots are large solitary ground squirrels which, like pikas, generally live in the mountains of Asia, Europe, and North America.  The groundhog is an exception among the marmots since it prefers to live on open ground or at the edge of woodlands.  The deforestation of North America for farms and subdivisions has caused groundhog population to rise.  Although groundhogs are omnivores, the bulk of their diet is vegetation such as grasses, berries, and crops.  They are gifted diggers who construct a deep burrow with multiple exits.  This burrow serves as their chief living quarters and refuge from predators.  Since groundhogs enter true hibernation, they usually also maintain a separate winter burrow (with a chamber beneath the frost line) for the sole purpose of their months-long suspended animation.

A Groundhog Enjoying a Garden

Groundhogs, however, have a deeper utility to modern humankind than as primitive weather gods.  Devoted readers will know my fascination with liver research, and groundhogs are the principal research animal used in studies of Hepatitis B and liver cancer.  Since groundhogs are prone to a similar virus in the wild, they always develop liver cancer when infected with hepatitis B.  Laboratory groundhogs have thus been responsible for many advances in understanding liver disease and pathology–including the discovery of a vaccine for Hepatitis B and the realization that immunizing against hepatitis B virus can prevent liver cancer.  Currently 350 million people around the world are suspected to have hepatitis B.  Forty percent of those infected will develop chronic liver damage or cancer.  According to the World Health Organization, an estimated 600,000 people die every year from complications related to the infection (which is more than the total number of United States citizens killed in World War I and World War II combined).  Perhaps the Groundhog should be thought of as a profound benefactor to humankind thanks to its utility as a laboratory animal.

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