Introduction
The first appearance of polar bears was so many years ago as it is during the period known as Pleistocene. During that ancient time, polar bears appeared in larger sizes than it is the case today. “It is believed that polar bears emerged from brown bears which were separated by glacier around the region known as Siberia. It is after undergoing several evolutionary changes that they formed into the current body appearance and functioning which is different from that of polar bears” (Polar Bears International, 6). Polar bears existence is characterized and influenced by their behavior, habitat as well as reproduction and is currently found to be endangered as discussed below.
Polar Bears Reproduction Process
According to scientists and experts polar bears are slowly declining due to global warming. “Every five years the world’s climatologists assess current knowledge about global warming. Their latest report was just released. It erases any doubt about where this warming is coming from and warns that we ain’t seen nothing yet. Some biologists are saying the Polar Bear is doomed” (Meadows 2). In order for researchers to effectively address the problem of declining polar bear populations, it is imperative for them to realize that the declining populations are caused by a myriad of climatic, biological, and behavioral factors.
The female polar bears reach maturity when they are about five to six years, mating usually occurs on a bunch of ice that lasts for an extensive period of time during late March to about mid July (Bears 76). Polar bears are primarily private animals until it is time for the mating process to start. The males will start by courting females they are attracted to . Time of occurrence is in April and May each year. During this season most of the polar bears will have migrated to central hunting grounds. The males will fight violently with other polar bears for the right to mate with the females. Males are likely to get one female in their mind to mate with and will battle all others that desire to be with her. “Some of these males have been known to go more than 100 miles to mate with a female that they have picked up the scent of” (Polar Bears 1/2).
Male Polar bears have additional fur on their legs than females. “Researchers believe that this additional hair is very attractive to the females”. This gives them an advantage to choose who they desire to mate with. “It is compared to the mane of a lion which is also known to attract females to it for mating purposes” (Polar Bears 1/2).
It is not unusual for females to end up with only one mate. “DNA testing has proven that a litter of cubs can all be from the same father or from different ones”. Normally the mating process will go on for a week to guarantee that conception has begun (Polar Bears ½).
“After fertilization, the tiny embryo divides up a few times and then free floats in the uterus, not to resume development until September, when it finally implants in the uterine wall” (Bears 76). The females will normally gain 400 to 500 pounds through out her pregnancy. The hibernation is however unique; while other bears have lowered heart rates and temperatures during hibernation, the pregnant bear retains the normal body temperature only lowering the heart rate (Polar Bears ½). They go into their maternity dens in October to November and conceive one or four cubs (twins are frequent) sometime throughout December or January. The igloo like den is an imperative barricade against cold. Sightless and vulnerable, the cubs at birth are smaller than guinea pigs, weighing merely about 20 ounces each. They stay in the den until late March or April, developing rapidly on their mother’s milk which is loaded with fat (Bears 76). This dependence on the mother polar bears continues up to two and a half years. More than 60% of the cubs born, die before they are one year old. This is usually a result of harsh climatic environment and predators (Polar Bears 2/2).
In conclusion, addressing the extinction threat against polar bears has remained a major challenge due to varying causes of low reproductive rates. These low reproductive rates are usually a result of; short mating periods, harsh climatic conditions and high levels of cub mortality. High levels of cub mortality may result from; maternal neglect, predation, or killing by male polar bears who may view the cubs as a threat. Low reproduction rates are also caused by the fact that female polar bears are induced ovulators and only ovulate for a few years in their lifetime. To eliminate the extinction threat against polar bears scientists therefore need to address all these causal factors.
Dynamism of polar bears habitat
A study conducted on the current rate of polar bear occurrence on land compared to what was experienced some years before shows that there is a considerable dynamism of habitat. That is, according to information from studies ranging from 1979 all the way to 2005, there is a higher polar bear occurrence on land as well as in exposed waters.
On the other hand, polar bear occurrence on ice continues to decrease by the day. These findings imply that there are currently more chances of the interaction of human beings with bears than it was the situation in earlier days. These findings also showed that the more ice conditions continued to change, polar bears also diversified in terms of habitats.
This is confirmed by the situation whereby, “the period from 1979 to 1987 recorded 12% population of polar bears in habitats with no ice. This particular percentage increased in the period from 1997 to 2005 whereby 90% of the very population lived in areas with no ice. An associated observation was on the ice occurrence which continued to reduce considerably over the years” (Arctic Institute of North America, 2). The conclusion of the study was that the increase of occurrence of polar bears on land happens to be because their favorable habitat is diminishing.
Polar bears behavior
The manner in which polar bears behave can be categorized into their daily activity, their mode of movement, social structure, tracking, attacking humans, hibernation, as well as social behavior. Regarding their bears daily activity, it is found that they are normally more active on the beginning of a day compared to the end of the same day.”In case a polar bear is not hunting, it spends its moments sleeping or just having a rest. This varies with weather, as during warm days, they normally spread out on ice or dry land at times facing upwards with feet lifted up. This is normally different during cold days as they curl up wrapping their muzzles” (Seaworld org. 1). On winter, polar bears normally look for natural shelters where they stay temporarily and keep warm.
The kind of movement assumed by polar bears is walking as well as running in a manner almost similar to that of human beings. They make use of feet soles to walk whereby their heels are the first to come in contact with the ground. They are also in a position to support selves using hind feet which in turn allows them to cover considerably short distances as they walk upright. “The two pairs of polar bears feet do not move concurrently but each moves at its own time starting with the one on right front, followed by left hind, left front and lastly right hind” ” (Seaworld org. 2). Though their walk is usually steady, it is accompanied by heavy steps hence producing a great sound on the great.
Social structure assumed by polar bears is characterized by solitude since there are only two distinct social entities in existence including breeding pairs as well as adult females in the company of cubs. However, there are certain occasions whereby polar bears appear in aggregations particularly on land during summer.
“Social interaction among polar bears is normally constant between females and their young ones as the mothers tend to be very attentive as they touch as well as tidy up their cubs frequently” (Seaworld org. 4). Occasional social interaction is also witnessed between breeding pairs that stick together for a period of about one week during which they mate severally.
When polar beggars are in aggregations, adult males are sometimes found to engage in play fighting but they fight when any of them is spotted attempting to court another bear’s breeding partner. More so, the young ones normally play together as they chase and undertake their siblings.
It is found that not hibernation is not exercised by every polar bear but is in mostly done by females. “These females’ temperatures tend to drop slightly and it is during this period that they give birth. Another characteristic feature of polar bears in hibernation is the shift of heart rates from a normal of 46 beats dropping to 27 beats in a minute” ” (Seaworld org. 4). During hibernation, the females tend to be easily aroused and normally sleep very soundly.
In situations whereby there is overlapping of polar bears dwellings with those of humans, there are some attacks encountered. This is particularly in towns, hunting camps as well as weather stations. Polar bears are also found to enjoy feeding on humans whom they kill if they do not happen to be killed first.
Study results shows that “in a period of about thirty years, the number of people reported to be killed by polar bears in Canada is eight, US has one while there are 19 in Russia. The main characteristic of these killings is that polar bears involved are normally provoked in one way or another. This number is predicted to increase due to the current trend climatic conditions whereby summers are longer than winters hence leading a larger group towards dry land where humans live” (Polar Bears International, 9).
In conclusion, recent studies have confirmed that polar bears existence is endangered with the main reason being the occurrence of warmer and warmer climate. This results to the melting of ice which is the breeding area for these polar bears. More so, as polar bears continue to move towards dry land in large number they get in more contact with human beings who hunt them hence contributing to their reduction.
Work cited
Arctic Institute of North America (2010, January 7). Polar bears changing habitat in response to sea ice conditions. ScienceDaily. Retrieved March 21, 2010, from http://74.125.93.132/search?q=cache:XdWKCdKzXQoJ:www.sciencedaily.com /releases/2010/01/100107151657.htm+polar+bears+population&cd=13&hl=en&ct=clnk&gl=ke
Polar Bears International, Bear Essentials, Polar Style – Polar Bears International, retrieved 2010 from, www.polarbearsinternational.org/polar-bears/bear-essentials-polar-style
Seaworld org. polar bears, retrieved march 2010 from http://www.seaworld.org/infobooks/PolarBears/pbbehavior.html
