On Temperature and P olar Bears

Frequently, on this site, especially on the journal pages, were comments about the temperature.  The more intriguing mention of temperature was the windchill.  There are days when the windchill temperatures were -1700 and -1900.  The school closes around 2200-2400!  Now, really, what is this?  In this section, an attempt will be made to answer this question.  The explanation will be based on information from the Atmospheric Environment Service division of Environment Canada.  The stronger the wind speed, the colder it will feel even though the actual air temperature has not changed.  The rate of cooling is called the windchill factor.  This effect can produce uncomfortably cold and dangerous conditions that are not indicated by the air temperature alone.  Windchill indicates how quickly an object that is warmer than the air will lose heat and cool down to the surrounding air temperature.  The effect of windchill on people will vary depending on their level of physical activity and the amount of sunshine.  In Canada, the windchill factor is measured in Watts per square meter (W/m2).  This represents the rate of cooling or more specifically how quickly heat is lost from an exposed warmer object.  Here are some examples of the windchill factor in W/m2.
    1000 - Conditions are comfortable when warmly dressed
    1400 - No longer pleasant, even on sunny days; frostbite possible
    1800 - Freezing of exposed skin begins depending on activity levels and sunshine
    2300 - Walking outdoors becomes dangerous, exposed facial areas freeze in a minute
    2700 - Exposed flesh will freeze within 30 seconds; dangerous conditions
According to other data, windspeed that is less than 6 km/hr have little effect on the windchill values.  And, windspeeds greater than 64 km/hr have little additional chilling effect.  Whatever the case, these numbers of the windchill factor do sound dramatic!!
 

Now, what about the polar bears?  The Churchill area (northern Manitoba) actually hosts the world's largest concentration of polar bears.  Each year, the bears move along the coast, waiting for the ice to freeze in anticipation of the winter hunt of seals on the frozen expanse of Hudson Bay.  The bears do not fill up the town and are not normally found behind or under each house or down each street.  But, there are occasions that a bear may wander through the actual town of Churchill.  Most polar bears are found outside of Churchill, actually heading to a point that juts out into Hudson Bay known as Cape Churchill.  Most of the bear activity in the Churchill area takes place during the months of September, October, and early November.  Sometimes, though, there is a chance that someone may encounter a polar bear along the rocky shoreline or some other area.  The scientific name of the polar bear is Ursus maritimus meaning a maritime (or sea) bear.  Visitors (and residents) of this area are reminded that the land is a place for bears and people.  And, that the polar bears are one of the natural hazards in these northern areas.  Polar bears can injure or kill people (as mentioned in the journal pages).  These animals are the largest land carnivores in North America.  They have an incredible sense of smell.  They can detect seals several miles away, hiding under the ice!  They also have acute vision and hearing.  Polar bears, like most bears, are extremely curious and fast learners.  Brown and black bears tend to avoid people, but polar bears might come right over to see you!  Each tends to have a distinct personality and are individualistic.  It is possible to predict behaviour patterns, but separate actions are different.  With this in mind, visitors (and residents) are reminded that is unlawful to bait, feed, touch or disturb a bear.  There are several populations of polar bears around Canada, Greenland, and Alaska USA.  The world population of polar bears is estimated to be 20,000-40,000.  It is hard to determine, as most places where they exist are inaccessible.  The Wapusk (white bear) National Park population numbers around 2000 (this is the Churchill population; but not this many are seen in the area).  Not all of these bears leave via Cape Churchill, but many do.  In Hudson Bay, there is a counterclockwise current.  This current picks up freshwater from the rivers that drain into the bay.  The freshwater freezes first (the bay is saltwater), so the ice forms first.  The bears have waited several months, not eating, for the chance to go onto the ice to hunt ringed- (90%) or bearded-seals (10%).  While they are waiting for the ice, they might chew on kelp (seaweed) or sedge grasses and maybe even a few berries.  Eventually, the bears set off on their own, and the females that have cubs leave with their offspring which will either be 10-11months old or their two year olds.  The adult female not only has to hunt and feed their offspring, but they also must protect the young from adult males.  An adult male may attempt to kill the cubs in order to mate with the female.  In most cases, the female can thwart attempts of the male until she has reared her cubs for the two year duration that they stay together.  The bears will mate on the ice, but the female has a delayed implantation process, as she must have at least 440 pounds (200 kg) of fat stored up.  The implantation takes place after she leaves the ice in June, and the fetal development starts in August.  The young bears are born at a weight of 16-24 ounces.  They are born blind, hairless, and stay in the den that the mother has made in the snow or ground for 3 months.  The Wapusk population dens are about 60 miles southeast of Churchill, near the Owl River.  There is known to be a 38% mortality of polar bears cubs under the age of 4.  Eventually, the bears grow and will be able to kill a seal weighing 120-130 pounds.  They will only eat the skin and fat of the seal, so the little arctic foxes will follow the bears for the scraps.   They might even clean up the waste of the polar bear.  Sometimes, though, the foxes will follow the bears too far out on the ice and become stranded and will drown.  A polar bear can run up to 30 mph for about 50 yards before they overheat.  They normally have 48 beats per minute of their heart, but after a run, that will increase to 150.  These animals normally live around 18 years.  Oldest known  polar bear (based on tooth ring examination) was 32 in the wild, and in captivity 41.  The heaviest was 2217 pounds, but normally up to 1600 pounds.  Most of this information is known by the tagging and data collection process.  Currently, ear tags which are white in color (and blend well) are used.  In the past, researchers used very obvious paintings on the fur or large bright colored tags that hung out of the ears.  Realizing that this was not desirable by those that pay large sums to come to see the bears and not pleasing in photographs, the tags were changed.  The Department of Natural Resources conducts the research.  After tranquilizing the bears, they gather data such as the weight, health, age, blood sample, and check on toxin levels (such as PCB's and DDT).  Are the polar bears hunted?  Polar bears are only allowed to be hunted by the native community.  There are maximum amounts of bears that may be killed in each population.  This does not mean that the entire quota may be killed, but the total may not exceed that amount.  The "tag" rites to hunt a bear can be sold to a non-native.  The cost for each tag is $15,000 and a native must be along for the kill as a guide.  There are additional regulations as well.  At the time the military had a large presence in Churchill in the 1950's and 60's, polar bear hunts were very common (this was before the quotas were implemented), and the number of polar bears significantly decreased.  Today, thanks to the protection and management set forth by the Department of Natural Resources and by Parks Canada, the numbers of polar bears has increased.  It was the fur that was desirable.  The skins may have been used as rugs, stuffed animal displays, or trophies.  The fat and liver usually contains toxins and they are extremely poisonous.  The skin of the polar bear is black.   The fur hairs were thought to be similar to a fibre optic cable by conducting the light/heat energy to the skin.  In reality, according to a recent study, the hairs, filled with keratin, are excellent absorbers or UV (ultraviolet radiation) and in turn, the pelt does not release it.  Polar bears are known to be one of the most heat efficient animals.  Infrared testing has been done on them, and in most cases, the bears do not show up! (according to conversation with some park naturalists).   The polar bear makes very little noise.  Sometimes on television, the scene will show two male polar bears sparing.  Their mouths are open and then suddenly they roar and groan.  Actually, the sound effects folk in the studio added this to enhance the visual effect.  It is not common to ever hear a polar bear make a sound.  The cubs may whimper for the mother, but that is far from vicious growls and roars!  It is important for the bear to be quiet, as this aides in its hunting skills.  The bears may even get down in the ice or snow and cover their noses, so the black spot does not give them away!  They may only catch one out of every six seals they go after.  They may wait by the air hole of the seal for hours waiting for it to come up to breathe.  They may smash through a seal den with jack-hammer strength to drag out a seal.  The bear paw is partly webbed to help in swimming up to 60 miles a day; they have large rough pads to keep them from slipping on the ice; they are covered with fur on the bottom as well to keep them warm and not stick to the ice; the claws are short and sharp for ripping and tearing; and the paw itself is big and heavy to break into the seal dens or fight an enemy.  Polar bears are incredible animals to watch.  They have amazing features that seem to attract people to view them.  They have the look like one could pet them or hold them.  These endearing features are also ones which could actually get a person killed.  They deserve the respect that the Lord of the Arctic should have.   This information was based on conversations with officials of Parks Canada (Churchill/Wapusk); Manitoba Department of Natural Resources; Tundra Buggy Tours, Ltd.; and from bear biologists and researchers.
 

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