Hibernators Large and Small

Winter strategies for species without central heating span migrating, toughing it out and hibernating. That last option - damping down the metabolism - has been taken up by species ranging in size from large to small.

Black Bears: In the late summer and early fall these New England neighbors double to triple their food intake in order to add an inches-thick layer of body fat. Come fall the bears find a confined space for a den such as under the trunk of a fallen tree. The den offers some physical protection from the elements, but is not warmer than the outside temperature. Body temperature drops to about 90F degrees and heart rate slows to ten beats per minute (bpm). This semi-hibernating state last for months, but if disturbed a black bear can achieve a fully roused state within minutes. One large puzzle is how bears manage the winter-long rest without needing to eat, drink, urinate or defecate, nor suffer from the bone loss and muscle atrophy humans would undergo from the equivalent months of bed rest.  

Woodchucks: Also known as groundhogs, these mid-sized mammals are true hibernators. They gain thirty percent in body weight, almost entirely as fat, before entering a den in late October to begin a months-long state of torpor: body temperature dropped to 40F degrees, heart rate dropped to about five bpm and breathing rate decreased to less than one per minute. Roughly every two weeks the hibernating animals rouse to full awareness, go to the bathroom and undergo a day or two of normal sleep in order to catch up on their dreaming (confirmed by rapid-eye-motion type sleep). If this coincides with February 2nd then it is Groundhog Day. One puzzle: what late summer signal triggers the beginnings of over-eating to gain all that weight?

Chipmunks: These ground-living relatives of squirrels add some body fat in the fall and store caches of food – primarily seeds – in their underground burrows. The burrows extend below the frost line. Chipmunks enter an intermittent hibernating state. Body temperatures approach 40F degrees. Heart rate slows from 200-300 bpm to under 10. Every few days the chipmunk warms back up to close to 100 degrees and becomes active. Separate areas of the den serve as food larder, bathroom and bedroom. Come late winter the males will begin to surface-wander in search of dens of females. One consequence - spring litters tend to have only one father, whereas summer litters are likely to have multiple fathers.  

Yellow Jacket Wasps: In the fall the virgin queens leave their mother's nest to mate. Like honey bees, yellow jacket queens will mate with 3-10 males. The males die. The fertilized females hibernate under tree bark on in another dry place. Insects have a few hibernating strategies to choose from. Some synthesize glycerol (antifreeze) in order to lower their freezing temperature. Some select a dry place to stay and supercool without ice crystal formation. Others allow themselves to freeze, and in fact synthesize freeze-promoting proteins, with the idea that freezing s-l-o-w-l-y and then remaining frozen all winter reduces risk of large ice crystal formation which would poke holes in cells. Yellow jacket queens employ glycerol and supercooling. Coming out from under hibernation is not triggered by an internal signal. Rather, the yellow jacket queens depend on the warming temperatures of spring to bring them back to life.

Warmer winters in Alabama and other south eastern states have led to an interesting phenomenon. Rather than the nest dying from the cold there is enough food and warmth to get through the winter as an active colony. Come spring, the colony re-expands, and related daughter queens set up housekeeping next door. So instead of scattered annual colonies there is a multi-year, condominium-like complex making up a super-colony of tens of thousands of related but not genetically identical yellow jacket wasps. 

Must be Willing to Eat Bitterness

English translations of help-wanted advertisements in mainland Chinese newspapers might include the phrase “must be willing to eat bitterness.” This is not a mistranslation. The traditional phrase“吃苦” transliterates to Chi Ku (pronounced Cheh Qwea) and translates to “eat bitter, eating bitter” or “eat bitterness.” Meanings for the phrase encompass prevailing over misfortune or in general, to be able to endure hardship. The term is familiar to students of Chinese martial arts. It can include being willing to work hard and suffer now in order to reap the benefits of one’s labor at a later time. 

Eat bitterness (Mandarin)

When a prospective employer in China was asked what he meant by “must be willing to eat bitterness,” he replied "I want workers who will each do the work of two and do two days work in one." Many factories have dormitories, and dozens of rules for controlling behavior while working and not.

Once upon a time, factory workers in Maynard, Massachusetts were also expected to do the work of two and do two days work in one. Much as in present-day China, workers lived in boarding houses owned by the wool mill. Expenses such as rent and meals were subtracted from their pay. Anyone unable to work due to illness or injury was fired. And evicted. Hours were long. A man’s salary was often not enough to support a family, so his wife and/or children would also work in the mill or in mill-related businesses. Children, because of their smaller size, were hired to clean and service dangerous mill machinery while it was in motion.

The Assabet Manufacturing Company [1847-1898] had rules for employees. According to a 1863 poster reprinted in the book “Assabet Mills,” employees  were expected to observe the Sabbath…and be temperate (not consuming alcohol) skillful and honest. Quitting workers had to give two week’s notice in order to get their last paycheck, but could be fired without notice. There was a 9:00 p.m. curfew after which workers were expected to be off the streets.  

The industrial revolution in the United States developed against a backdrop of a transition from labor scarcity to labor surplus. In the 1700s, as Native Americans were increasingly marginalized, the colonizing countries filled the land with emigrating religious minorities, indentured servants, convicts and slaves. Families always had enough chores on the farm to keep everyone busy. One hundred years later the inherited farmland, of fading fertility, had been divided amongst inheritors into smaller farms. Sons and daughters, now representing a labor surplus, sought factory work in cities.

Immigrants, too, came to America to take on any hardship as better than the hopeless, wretched life left behind. The town of Maynard saw influxes of Irish, French-speaking Canadians, Finns, Russians, Jews, Italians, Poles and other immigrants. Many of them accepted horrible working conditions in the hope that life would be better for their children.

For example, in 1912, Maynard’s male mill workers were making 11 to 16 cents per hour, and were pressing owners to reduce the work week to 54 hours – five 10-hour weekdays and only a half-day on Saturdays. This when a new Ford Model T automobile cost $690. Women and males under the age of 18 were working “only” ten hour shifts (for less pay per hour) because their workday had been set by the Massachusetts Ten-Hour Act of 1874.

Americans have to some degree lost the willingness to “eat bitterness.” Instead, many think that mysterious “laws” of attraction, manifestation, abundance and prosperity will reward us with the materials of wealth and health if we just visualize them with enough clarity. An internet search on the term "laws of abundance" finds thousands upon thousands of hits. But in the real world, if a person does not "eat bitterness" they will find that "someone else is eating their lunch" (taking their share of prosperity).

Hydropower at the Woolen Mill

Vertical drop in feet times flow in gallons per minute divided 

by 10,000 equals kilowatts, and kW x 1.34 equals horsepower.

Deep in the bowels of Clock Tower Place there is a space where an antiquated monster once sat – the turbine which converted water power to electrical power. This machine was the last of several generations of hydropower generating engineering in the mill.

Hydropower is all about high school algebra. Vertical drop in feet times flow in gallons per minute divided by 10,000 equals kilowatts, and kW x 1.34 equals horsepower. For the metric-minded, vertical drop in meters times flow in liters per second times 9.81 divided by 1,000 also equals kilowatts. By this math, ten gallons of water dropping 100 feet yields the same power as 100 gallons of water falling ten feet.

Actual power yield is always less than theoretical due to friction and other inefficiencies. An “undershot” waterwheel describes a design with water running under the wheel, pushing the bottom blades forward. For wooden wheels of this design capture of the water’s energy was on the order of 20 to 30 percent.

Wherever greater vertical drop allowed, water was led over the top of the wheel to pull blades downward by force of gravity. This style, referred to as “overshot,” traditionally captured 50 to 70 percent of available energy. By the 1830s wheels would have had wooden blades, rims and spokes attached to iron hubs and axles. Late in the 1800s the Fitz Waterwheel Company was selling all-steel waterwheels, with the advantages of nearly 90 percent efficiency plus resistance to icing in winter.      

Ben Smith dam stored water for the woolen mill

Back to Maynard, or what at the time was known as Assabet Village. Construction of the Ben Smith Dam, the mill pond and the canal between the two in 1847 resulted in a large, year-round water reserve at an altitude above sea level of 175 feet. Outflow from the waterworks would have reentered Assabet River below the mill at an altitude of 155 feet. Flow rate through the system is not known, nor design, but a good guess is two overshot wheels each with a 15 foot drop and a combined flow of up to 45,000 gallons per minute.

That flow is equivalent to 100 cubic feet of water per second (cfs). For comparison, the Assabet River has a year-round average of 200 cfs, but summer months average under 100 cfs. Keep in mind that water power production was never around the clock. Flow through the mill was stopped at the end of the workday to back up as much water as possible in the millpond for the next day.

Power production was approximately 50 horsepower. As Maynard’s mill operations grew, water power was supplemented by coal-fueled steam power, hence all the historic images with smokestacks. The book “Assabet Mills” states that by 1879 nearly 40 percent of power was from steam engines. A different source states that the first steam engine was installed in 1862, when Amory Maynard was increasing capacity to meet Union Army contracts for wool goods. 

At some point the waterwheel complex was replaced by a turbine. Turbines are much more compact than wheels. Water drops down through a progressively narrowing pipe. This water, now under high pressure, jets into the turbine chamber at high speed, spins the turbine blades, and exits out the bottom. Turbine efficiencies rival the best wheels.

Records show a hydroturbine used to generate electricity from 1902 to 1968, with a hint that Digital Equipment Corporation may have refurbished the power plant in 1983 and run it until 1992. The Clock Tower Place 2002 petition to surrender electricity generating rights described the last operative turbine as having a pass-through of 128 cfs and production of 125 kilowatts of energy.

CTP has recently had some second thoughts about alternative and renewable energy sources, and according to Joe Mullin, CTP’s Public Affairs Director, is tentatively exploring the process of restoring hydroelectric power generation. Currently, the turbine is long gone, the smokestack is merely a support for cell phone antennae, and all of the kilowatt-hours used to power CTP by day and light up the windows by night are wired in from elsewhere.

Coda: According to an article in the March 14, 1902 issue of The Maynard News, the switch to electric power included the installation of two vertical compound engines directly connected to electric generators. The engines would have been steam engines powered by either coal or fuel oil. The power of the two engines was 2,500 and 800 horsepower. From this time forward hydropower was clearly a minor portion of total energy production at the mill complex. Employment at the newly enlarged complex owned by the American Woolen Company was 2,000. 

Assabet River National Wildlife Refuge

Hunting is allowed in our neighboring wildlife refuge. Details first – the Massachusetts deer hunting season runs from mid-October to the end of December, is limited to bows, shotguns and muzzle-loading rifles, and never on Sundays. These are all short-range weapons compared to hunting rifles, hence lowering the risk of accidental shootings. The application deadline was back in July. The Assabet River National Wildlife Refuge also has hunting seasons for turkeys, grouse, woodcock, rabbits and squirrels. Deer hunters must wear orange. During hunting season, so should you.

Origins of the Refuge date back to the 1942 seizure of land spanning Maynard, Sudbury, Hudson and Stow by federal eminent domain. Landowners were given about ten days to pack up and leave, and by their own accounts received around ten cents on the dollar of what the land was actually worth.

Blueprint of munitions bunker [click to enlarge]

One of the most interesting features of the Refuge is the World War II era ammunition bunkers. The site was chosen to be convenient to railroad shipping to the Boston Navy Yard, which was active over the years1801-1974 and currently home to the USS Constitution, yet far enough inland so that a German battleship could not shell the area. Each of the 50 bunkers, officially referred to as “igloos,” has inside dimensions of 81x26x12 feet, with a curved roof. Sides and roofs were mounded with dirt for extra protection and disguise. Today, from all but the door end, these bunkers resemble small hills, complete with a forest of trees growing on top. Bunker #303 is sometimes open for tours. 

After WWII this site, referred to as the Fort Devens-Sudbury Training Annex, served as a troop training ground, ordinance testing and laboratory disposal area for Natick Labs, i.e., the U.S. Army Soldier Systems Center. A 1980s assessment led to this being categorized as an EPA “Superfund” clean-up site in 1990, as the site was contaminated with arsenic, pesticides and other chemicals. Extensive Army clean-up efforts continued for years, ending with the site being turned over to the U.S. Fish & Wildlife Service in 2000, to turn into a wildlife refuge.        

Tour of Bunker #303

The Refuge covers 3.5 square miles. The prime purpose is to manage land for migratory bird conservation. A website (www.farnwr.org) maintained by Friends of the Assabet River National Wildlife Refuge has maps, photos, activities, and a link to the government’s Refuge website. There is a wonderfully informative, child-friendly, Visitor Center at 680 Hudson Road, Sudbury. For people who just want to park and roam, the north parking lot is accessed from White Pond Road, reachable from Route 117 in Stow. Within the Refuge there are 15 miles of old roads and new walking trails, with the old roads, which are in poor repair, open to bicycles. No dogs allowed anywhere in the Refuge, no other pets, no horses, no fires, no overnight camping, no ATVs, no dirt bikes, no snowmobiles. Use of the Refuge is currently free, but that is likely to change. 

Back to deer hunting – this is an example of a need to manage a native species acting like an invasive species. Unrestricted hunting through the 1800s resulted in the New England extinction of wolves and mountain lions, and near-extinction of whitetail deer. But what with restrictions on hunting and return of farmland to wilderness, the state’s deer population is roughly 100,000 or 10 per square mile, and much higher in favorable terrain. Without population management of some sort, deer destroy ecological balance. ARNWR allows deer hunting so it will be a refuge for all wildlife, not just deer.

Trees growing on top of bunker, next to roof vent

One gray wolf made his way from Canada to western Massachusetts in 2007. Unfortunately he took up sheep killing rather than deer hunting, and was shot. A mountain lion walked from South Dakota to Connecticut, where he was then hit by a car in 2011. If more apex predators emigrate from the west then the Refuge will become a more interesting place to walk, as these animals hunt year round, including Sundays.     

Death by Exercise, Marathon, Triathlon

Sudden cardiac death – as in the college-age basketball player or the hyper-fit triathlon participant – tends to make the news. As it should. Newsworthy death while exercising provides every non-exerciser with rationale for not exercising. “See” they say, “this person was an avid runner [cyclist, swimmer] and dropped dead at 40.” The contrarian point being that the endurance sports that are supposed to protect against heart disease sometimes appear to do just the opposite.

There is an iota of truth to this observation. Estimates are that just under one person per 100,000 participating in a half-marathon or marathon, or 1.5/100,000 participating in a triathlon race will die during or immediately after the event. The great majority of triathlon deaths occur in the swim phase. Figure a collective three million participants in these types of races each year and that comes to maybe 30 deaths per year. There are fuzzier estimates of perhaps one sudden death per every million exercise event for other forms of exercise. So the true answer is yes, exercise can kill the physically fit, but no, not a risk factor worth avoiding exercise entirely.

There is more truth in the observation that exertion by the physically unfit can result in fatal cardiovascular events. The classic case is the middle-aged office worker who drops dead shoveling snow while attempting to clear the driveway and get to work. Contributing factors include the fact that blood pressure peaks in the morning a few hours after waking up, and the fact that exertion in cold weather constricts arteries, further adding to heart stress (triathlon deaths in cold water probably for the same reason). Snow removal related heart attacks frequently occur in women and men with no known pre-existing heart disease.

Exercise can also result in accidental death. In the U.S., walking, running, bicycling, swimming, boating and winter sports add up to about 10,000 deaths per year. Subtract half who are either children or are adults under the influence of alcohol (as in walking or riding a bike home from a bar, at night), and it’s still a big number. But the total pales compared to the 2,500,000 total deaths per year, of which many are premature cardiovascular deaths brought on by a lifetime of inactivity.

The good news is that benefits from even modest amounts of exercise are becoming clearer. In a 2011 article in The Lancet, C.P. Wen and co-authors reported that for a multi-year tracking study of 416,175 Taiwanese adults, as little as 90 minutes per week of moderate-intensity exercise reduced the risk of death by fourteen percent. Each additional 90 minutes per week added four percent further reduction. Other studies have also reported the greatest improvement for modest exercise compared to no exercise at all, and diminishing returns for progressively more exercise.

The theory that over-doing exercise may cause more harm than good has neither been confirmed nor disproven. A science journal article by Masaru Teramoto reviewed fourteen studies of longevity of elite athletes. Athletes from endurance sports had 3-6 year longer life spans than the general population, but the results were mixed for athletes in power sports. The latter may be disadvantaged by larger body size typical of their sport or from a discontinuation of exercise as they age. The authors caution that elite athletes may by genetically different from the population as a whole, with both their abilities and lifespan being consequences of their genes rather than one causing the other.

There is a non-fatal problem with exercise – it is potentially addictive. As one well-known fitness expert author put it, “…people reduce their lives to fitness routines, training as many as 40 hours a week. That the effort may wreck marriages and compromise immune systems isn’t even relevant. To these people – demographically a diverse lot – exercise is addictive. The more the body gets, the more it wants. In return, the drug of exercise infuses the swimmer, cyclist and runner with two powerful illusions: that he/she is escaping the horrible, and progressing toward the divine.”


Beyond the story: Exercise-related articles on this blog include "Avoiding Overhydration" (Feb 2010), "Hypothermia" (Nov 2010) and "Recovery from Donating Blood" (March 2011). For a detailed, referenced take on death from exercise, go to the entry "Sudden Death and Exercise", in the Encyclopedia of Sports Medicine and Science:  http://www.sportsci.org/encyc/suddendeath/suddendeath.html.