There are several factors threatening the continued existence of polar bears in the wild. The most vaunted of these currently is the threat of habitat reduction due to climate change resulting from global warming. Whether this is actually the most serious threat is debatable. If polar bears do become extinct in the wild, it is probable that captive polar bear populations will soon follow. Certain physiological and behavioral traits intrinsic to polar bears make captive breeding programs problematical at best.
Recently there has been intense public interest in zoos where polar bear mothers have rejected their young, on whether they should be rescued and nursed by the keepers or allowed to die. The concept on allowing them to die is that it is the way of nature. This is a faulty assumption at best. A captive situation is in no way “natural” for an animal that is migratory by nature and has specific behavioral and physiological requirements to facilitate motherhood. Expecting the mother to show normal maternal behaviors towards cubs born in such circumstances is naive, even if she was allowed to produce in a natural den she was given the opportunity to build for herself. Any such birth is a miracle and all such should be succored, preferably by the mother, but when that does not occur, then it is our responsibility to do so in her stead.
While being hesitant to say that a reduction in ice formation, cover and duration due to the effects of climate change resulting from global warming is the primary threat to polar bear continuance, it is certainly a considerable one. Where previously finding a polar bear that had drowned was virtually unknown, it is now becoming a relatively frequent occurrence. This is not happening because polar bears have suddenly developed the urge to swim distances beyond their capabilities.
The skin and pelt of a polar bear allows them to determine external temperature and more significantly, the position of the sun to an amazing exactness. Polar bears use this information to determine when to travel and in which direction. The significant point here is the angle of the sunlight, which effectively tells them when it is time to move in a different direction. In the past this has allowed them to move out of regions before ice melt has made them dangerous, now they are moving too late. This change is occurring too fast for them to adapt, so many polar bears are being forced to swim long distances and some are not making it.
The variations in ice cover and duration also affects hunting ranges. Bears that hunt over land-locked ice have ranges of 50,000 square kilometers while bears that hunt the ice of the seas have ranges of up to 250,000 square kilometers, as unbelievable as this may seem to us. This movement is primarily to keep them in touch with their main prey, seals.
This is becoming more difficult for them because man also hunts the seal. Their primary food source is reduced numerically to such an extent by human hunting that the relative abundance previously available to them is now greatly reduced. Where before a poor success rate was of no matter because there were so many to repeatedly try for, polar bears are failing to supply their needs on the same basis due to fewer opportunities.
Despite these challenges coming upon them so rapidly, it is still feasible that polar bears could manage to persevere. They are both intelligent and adaptable animals. Different genetic groups or “climes” of polar bears have behaviors suited to their particular situations. This demonstrates an adaptable and varied approach to the circumstances they face that could well stand them in good stead if these were the only problems they had to overcome.
Sadly, they have more problems to surmount. The one that may be even more significant than habitat loss, is one they have no way to avoid and no variation in natural behavior can save them from.
Since the use of poison gases in the trenches of World War I, humans have irresponsibly polluted the environment we live in with a wide range of poisons, toxins and generally dangerous pollutants. This has occurred to such an extent that genetic birth defects are found in polar bears in the Arctic, caused by the mutagenic properties of manmade organochlorines such as dioxins and PCPs (pentachlorophenols). These are accumulative poisons, the main “cleaning” organs of the body – the liver, the kidneys and the lungs – are unable to remove them to any significant extent, and so the amount found in not only the polar bear’s bodies but our own as well accumulates over time.
They do pass out of mammalian bodies in sweat, this is why a poisoned person may smell of the poison they have ingested. Unfortunately, the mammary glands are a specialized form of sweat gland. They share this characteristic, and will therefore contain a percentage of accumulated poisons in the milk provided in ratio to what the mother has accumulated through her life.
With polar bears this means that each new cub through drinking mother’s milk starts life with a similar level of accumulated poisons to his or her mother. Being at the top of their food chain, they then accumulate more from their diet, each generation ending up having higher levels than the one before.
It is estimated that one in a million genetic mutations may be beneficial, even if this was one in a thousand, the increased infant mortality of polar bear cubs this is likely to foresee may well exceed any survival problem incurred from global warming. It would be appallingly sad for us to succeed at slowing down global warming to the extent necessary to preserve polar bears only to see them die out anyway from the pollutants we have so casually discarded into the world we all share.
That is however, not all they face. Due to uncontrolled hunting through to the 1950s, polar bear numbers in the wild were reduced to an estimated 5,000. This led to the International Agreement on the Conservation of Polar Bears signed in 1973 by the governments of all nations controlling territory inhabited by polar bears. How much protection this actually supplies to polar bears varies. The illegal trade in polar bear skins and parts is big business. Organized poaching groups are often more numerous and better armed than the law-enforcement groups opposing them, especially in current day Russia. Even when successful in capturing poachers, bribable judiciary may release the culprits.
As wild numbers decrease, the value of their pelts and organs increase. The intensity and greed of their poachers will only increase as well. Following the self-centered nature and desires of their customers.
Unfortunately polar bears also face “legitimate” killing. As the ice takes longer to form, polar bears congregate in coastal regions for longer periods of time than previously. This is at the end of their hibernation period, understandably they are very hungry and not in the best of moods. The extended duration of their presence is increasing ecotourism ventures to “see” the polar bears. All factors considered it is hardly surprising that some bears are considered an endangerment to humans. Sometimes that is in expanded human communities where these ecotourism ventures are occurring and sometimes in mining situations that are encroaching on their habitual ranges.
Despite these appalling handicaps to their continued existence, the Canadian and Russian governments still allow a limited amount of trophy hunting of polar bears to occur. Enforcement agencies cannot aggressively oppose hunters in these nations because they must first determine whether or not they have licenses to hunt polar bears.
The likelihood that polar bears will still be an extant species in the wild or even in captivity in 50 years time seems a daunting proposition. They face a considerable up-hill battle to continue. All those that want their descendants to have the opportunity to see living polar bears need to do whatever they can to try to ensure their continued existence.
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