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In an ever changing world, there are more and more threats to wildlife and the need for conservation is at its greatest. Polar bears are one of the flagship species of conservation and there are many threats to their species that lead to a decline their in populations. The polar bear is the only land mammal species that uses the Arctic as its main habitat. Despite inhabiting one of least accessible areas on Earth to humans, the polar bear is been extremely vulnerable to anthropogenic impacts (Belikov et al. 2010) such as climate change, the drilling of the ice in search minerals or the effect of hunting. There are many conservation measures that are now taken by zoos to protect this species such as a Species Survival Plan (SSP), European Endangered Species Programme (EEP) as well as in-situ and ex-situ conservation which will later be discussed.
Polar bears are marine mammals due to their ice surfaced habitat belonging to the taxonomic family of Ursidae, which are dog-like carnivores or caniforms.
Polar bears are highly adapted for the harsh environment of the Arctic. The polar bears adaptations aid temperature regulation, hunting and movement. They posses a sensitive sense of smell, used to locate seals hiding under the ice and thick curled claws used to the rip flesh of their prey. Polar bears also posses excellent eye sight which helps them to see seals lying on the ice. Being bow-legged and pigeon-toed, polar bears are able to travel quickly and stop immediately when moving and with hair on the soles of their feet they have more traction when running preventing them from slipping on the ice (Bertalan, 2010). This allows the polar bear to initiate attacks on their prey well before the victim becomes aware of its presence.
Their diets contain a high fat content gained from the blubber seals posses which serves as insulation during the winter. As food is scarce without the fat they consume they would not survive long enough to find other prey due to a lack energy.
They posses webbed feet for ease of movement through water and a water repellent fur coat allowing for less exhaustive swimming (Stirling, 1988). The polar bears coat, used to regulate body temperature and camouflage the animal, changes colour annually appearing white in the winter months and yellow during the summer before moulting.
During the months of April and May courtship and mating occurs in the best hunting areas. Polar bears are polygynous and males often engage in fighting with other males, frequently resulting in injury, for the rights to mate with a female. Males and females stay together for up to a week mating. The female gains 200kg the summer months in preparation for the winter and starts to prepare a den for her cubs in snowdrifts or permafrost (Sterling, 1988). Males however, spend the winter wandering the ice. When the den is complete the female enters a non-continual dormant state. Between Novermber and February, two cubs are born on average, weighing less than a kilo each (Rosing, 1996), they are blind and helpless. The family emerges in mid-April making their way towards the ocean where seals are plentiful. At this time females must be weary of males as they easily prey upon young cubs. For up to the first two and a half years of their lives the cubs will remain with their mother before being weaned and abandoned by her.
Female polar bear usually begin to breed at around the age of four, whereas males reach sexual maturity at around six years old. A Hudson Bay study showed that the maturnal weight and the reproductive success of females were seen to peak when they reached their mid teens (Derocher, Stirling, 1994). It is apparent that instead of dying of old age, starve due to the weakness old age can cause.
Polar bears aren't usually territorial and tend to shy away from confrontations but attacks are often predatory and are usually fatal. Adults are solitary but from time to time they have been observed when playing with eachother and sleeping besides one another (Bruemmer, 1989).
Conservation status and distribution
Found only in the Northern Hemisphere the polar bear is currently classified as Vulnerable by the IUCN Red List of Threatened Species, with the population actively decreasing. There is thought to be a total of 20,000 to 25,000 individuals in the wild that make up nineteen theorised subpopulations (Schliebe et al. 2008). Their range is limited due to their reliance on the Arctic habitat however can be found in areas such as; Alaska, Canada, North Russia, Greenland and East Siberia (Amstrup, 2003), depending on availability of food.
Threats to its future survival in the wild.
One of the most obvious threats to polar bear survival is climate change, which indirectly causes starvation due to the loss of habitat incurred. As temperatures rise, the ice that polar bears use to hunt seals melts earlier in the year, causing greater difficulty in finding food or building up sufficient fat reserves for the coming winter months. Polar bears are then force to either swim long distances, using up their energy which occasionally causes them to drown or stay on the ice where it is difficult to gain access to seals below due to the deformed melting ice (Amstrupl et al. 1989). Polar bears deaths that are a result of drowning could rise in the future pack ice continues to melt (Monnett and Gleason, 2006).
Due to the lack of quality food, polar bears are less likely to reproduce, if they do it is probable that the cubs will not survive (Derocher et al, 2004). The melting ice can also force polar bears to migrate south in search of food, where an increase in human-polar bear conflict could be seen if bears come into close proximity to humans targeting rubbish dumps which can lead to fatalities for polar bears.
There are many direct threats to the polar bears future suvival in the wild. Polar bear hunting has existing for hundreds of years and provides trophies to recreational game hunters as well as meat and fur for commercial hunters to sell. Hunting brings about the potential risk of over-harvesting of polar bears and causes significant drops in populations, as many as 200 animals were be killed annually in the 1920-1930s (Belikov et al. 2010).
Humans seek to interfere with the Arctics natural habitat, when planning to exploit the area for mineral extraction. The Arctic is endowed with petroleum, minerals, fish and forests that increasingly attract the interest (Lindholt, 2006). Such interest could result in a loss of habitat for the polar bear altering feeding and mating patterns. Minerals such as; oil and gas are thought to lie beneath the surface of the ice and extracting any type of mineral could lead to contaminants being released and possibly affecting polar bears directly or affect their fragile habitat.
There are many different conservation measures taken by zoos to ensure the survival of the polar bear species. A Species Survival Plan could be one measure, which manages and conserves animals that are endangered managing ex-situ species, with the cooperation of the Accredited Zoos and Aquariums (AZA, 2010)
Housing, food, enrichment etc. (25%)
Consideration should be taken when designing enclosures for polar bears so they much meet all areas of social, psychological, behavioural and physical needs (AZA, 2009). Wherever possible their habitat must replicate that of their natural environment with groups of animals not exceeding number that would be present in the wild. It is possible to create dynamic, stimulating and comfortable environments for polar bears using innovative exhibit design, feeding and enrichment strategies to maximise their welfare reducing the possibility of stereotypic behaviour (AZA, 2009). Exhibits must contain platforms for resting, nesting sites and must comply with the Polar Bear Protection Act , they should also be given access to all areas of the exhibit at all times unless it is necessary otherwise (PBPA, 2002). The substrate of the floor is required to be made of a 'soft' material rather than hard (Ames, 2000). Using structures or large rock for climbing and other items for enrichment provides the polar bears with mental and physical stimulation as well as allowing them vantage points, which should be safely accessible to bears on any age.
Due to the vast expanse of the Arctic polar bears tend to benefit from adequately sized enclosures suitable to avoid other polar bears in the area due to their tendency to be solitary animals and important behaviours such as; swimming, foraging and running. Polar bears create nests in their natural habitat and the enclosure should occupy 1350ftÃ¯Â¿Â½ of floor space that is covered by soil, wood chips or another suitably soft substrate (PBPA, 2002) with areas so perform behaviours such as. The public should only be able to view up to 180Ã¯Â¿Â½ so that bears can avoid the public if they choose to.
Polar bears can be susceptible to most diseases that other carnivores contract. They can become infected with viruses, bacteria, parasites, protozoa and fungi (Dierauf & Gulland 2001), not only this but they can also develop nutritional disease and developmental problems among other illnesses. To keep Polar bears in zoos, an efficient veterinary service is critical to ensure an animals well-being. Visual exams are conducted on polar bears approximately every 6 months to inspect any changes in behaviour, feeding patterns, weight, overall physical appearance, respiration and stool quality.
Nutritional diseases can occur due to captive polar bears diet. Two hand-reared cubs were reported to have developed rickets, but were cured with a change in diet (Kenny et al. 1999). Dermatitis has occurred in polar bears due to a lack of vitamin A in their diets which would be readily available in the wild. But dermatitis is easily treated with a vitamin A supplement such as cod liver oil (Kock et al. 1985).
There are only two main Viral diseases the affect polar bears; rabies and morbillivirus. Although polar bear with rabies have been recorded, they are not a threat to to the overall wild populations nor in captivity (Taylor et al., 1991). Morbillivirus affects many wild polar bears but despite how common the virus is, it has been found to pose no serious threat to their health (Garner, 1996; Garner et al., 2000).
A bacterial disease that affects polar bears is leptospirosis which brings about symptoms of weakness, diarrhoea, jaundice and sometimes muscle spasms (Nall & Maetz, 1975). The disease is carried by rodents which makes it essential to keep them away from the enclosures. Vaccinations should be enforced to reduce the risk of contracting the disease.
Mycotic diseases such as blastomycosis is described in polar bears as a pulmonary disease (Dierauf & Gulland 2001) and symptoms include weight loss, increased lathargy and anorexia but with a treatment of 4.3mg/kg/day of itraconazole recovery can be made (Morris, 1989).
Regular worming treatments and regular faecal analysis can prevent parasites occurring in captive polar bears. Parasites can cause many problems to polar bears depending on their type. There are two types; internal and external. Internal parasites can be difficult to be rid of, symptoms include; diarrhoea and dramatic loss of weight which can lead to death. Polar bears are often susceptible to flea and tick infestations that causes irritation the skin.