Amazing Animals #5 The Polar Bear

The first time I clocked eyes on a Polar Bear on my TV I fell completely in love with them. When I found out where they lived I realised that it would be very unlikely in my life that I would ever see one in the wild.

In April 2015 as part of a University visit I went to Yorkshire Wildlife Park and it is a moment I will never forget. Walking around the back of the exhibit I had mixed feelings of a large mammal such as a Polar Bear in captivity, how we could house them without impacting their welfare.

The walk to the front of the exhibit took about 5 minutes before I realised the true extent of Project Polar. Set upon 10 acres dedicated to the project it at the time housed a single male Polar Bear, Victor, who had been retired for the European Breeding Program after siring 10 cubs. The largest exhibit holds 25.5 million gallons of water with the lake over 8 metres deep and there was Victor eating his carcass in the furthest point of his exhibit. I couldn’t quite believe the sheer size of

the exhibit itself and how much space they had dedicated to this single species. I stood for a long while taking photos of him before chatting to a keeper about the future. At the time, there was only Victors exhibit completed however the plan was to create two more identical exhibits side by side to house more male Bears, to which today they now have 4 Polar bears – Victor, Pixil, Nissan and Nobby and the two added exhibits completed. Little did I know back in 2015 that I would become friends with one of the keepers of the Bears and make plans to go up and meet them soon.

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Polar Bear Description

The Polar Bear (Ursus Maritimus) are the largest land carnivores in the world and are classified as Marine Mammals, spending most of their lives out on the Sea Ice of the Arctic Ocean. Sitting at the top of the food chain in the Arctic region, they are the most carnivorous of all bear species feeding primarily on Ringed and Bearded seals yet have been known to eat Walrus, Beluga Whale, Bird’s Eggs, Whale carcasses and rarely seen vegetation.

With no natural predators and no fear of humans this makes this animal extremely dangerous. The population has been divided into 19 subpopulations with of those, the latest information from the IUCN Polar Bear Specialist Group shows that there are three of the subpopulations in severe decline, and with a continued risk of decline in the future due to climate change.

The Bear is stocky with a long neck, small head, short rounded ears and a short tail. The male weighs between 410 to 720kg and can grow to 1.6 metres tall to the shoulder and up to 2.5 metres in length. The bear is able to absorb heat from the sun as it passes through its thick fur to its

black skin with an insulating fat layer just below the skin surface. The soles of their feet are covered in hair to protect and insulate them against the snow and to enable them to move across ice and prevent them from slipping. They have strong sharp claws for gaining traction and used for digging in the ice and killing prey.
The Polar Bears fur is made up of two layers- an outer layer that has long guard hairs and then a thick undercoat that has shorter hair. The coat has no white pigment as the hairs are hollow, this allows for the sunlight to pass through and get to their black skin easier. Their coat looks white due to luminescence where the sun’s rays bounce off the transparent guard hairs with light becoming tapped within the hair. This then bounces around the hollow part of the hair known as the reaction luminescence involving the emission of light. This allows for the bear to be camouflaged to its environment with the double layered coat insulating them from the cold air.

Behaviour

Polar bears are dependent on the pack ice in the Arctic region where they spend the majority of their time hunting, mating and building dens. Generally, the bear is a solitary species with exceptions through the breeding and cub rearing season.
Polar bears are extremely strong swimmers where they have been found and recorded 200 miles away from land using their front paws to propel them in the water swimming like dogs with the hind feet held flat used as rudders. They can swim at a speed of 6.2mph and can swim under water at depths of 3-4 metres where they can remain submerged for around 1 minute.

I will hand over the Sir David:

Source: Footage of a male bear swimming in freezing seas

The polar bears can make shallow dives when they are stalking prey, navigating through ice floes or when they search for Kelp. There is no known maximum dive duration however the longest bear dive observed and recorded lasted for a total of 3 minutes and 10 seconds that covered 45-50 metres without surfacing; it is estimated that a polar bear can dive no deeper that 8 metres.

Reproduction

Whilst adult Polar Bears are solitary, they are far from anti-social and will actively search for a mate during the Arctic’s Spring / early Summer season. During this Period Male Polar Bears will search for females and can pick up scent trails from as far as 100Kms away, once a male has found a female he will proceed to mate with her for around one week and will fight any other males that attempt to move in on his newly found mate, once the male has mated he will leave in search of another female, this type of breeding behaviour is called polygyny. The female Polar Bear needs to ensure that she has fed well during the Winter/Spring months as she will likely encounter very few feeding opportunities during the Summer, what food she can find will drastically increase the likelihood of her yielding viable offspring. Come the Autumn the female begins to dig a burrow within compacted snow or Sea ice, once built she will spend the next two to three months resting whilst waiting to give birth, she may be pregnant for anywhere between 6 and 9 months. Once born the Cubs will grow rapidly whilst feeding on their mother’s fat-laden milk, after two to three weeks the Cubs will take their first steps out of the Burrow where they will begin to gather their bearings and prepare for life on the snow / Sea ice, they will stay at their mother’s side for no less than two years where they will learn all the skills and hunting techniques that will allow them to survive as adults. Female Polar bears will not mate until they are at least five years of age, and males will likely not enter their prime breeding years until they are at least ten years old, whilst they can mate at a younger age they will have no method of competing against older more powerful males, so they must wait their turn.

Source: Footage of a Female bear leaving her den for the first time since giving birth

Arctic Adaptations

Most Bear species thrive in dense Forests with highly bountiful Rivers flowing through the land, this type of environment offers many ambush opportunities for the Bears can as such hunting is not an overly difficult task. Polar Bears on the other hand live their lives in a much harsher environment, the Arctic plains offer very little in the way of cover or camouflage, therefore Polar Bears as species have had to evolve certain adaptations that allow them to thrive in this demanding environment.

• As mentioned Polar bears are white, or at least they appear to be, their Fur is colourless. Both their thick undercoat and outer hairs are hollow and transparent, they gain their White appearance as the air spaces in the hair scatter light of all colours, this also means that not all Polar Bears appear white and may appear much duller in colour in low light environments. Nevertheless, their appearance does help them blend in with their surroundings during the Autumn/Winter feeding months, in the summer it has the opposite effect and greatly reduces their ability to hunt as they are no longer concealed against their surroundings.
• They’re very well insulated, they have a thick layer of Fat under their skin, which when combined with their thick layer of Fur (roughly 15cm) produces a very heat efficient animal, they can easily cope with average temperatures of -29C and can survive in temperatures as low as -55C.
• They’re energy efficient, Polar Bears can dictate whether nutrients are spent on general metabolic activity or if they are used for generating heat, they achieve this by producing more Nitric Oxide than other species of Bear, Nitric Oxide functions as a signalling molecule and enables the aforementioned nutrient usage.
  
  Source: A paw of an adult bear
• They’re paws are huge, they have the largest paws of any land carnivore and when combined with their large claws they are very capable of manoeuvring through icy/snowy terrain.
• A large number of successful hunts occur from ambushes from the Ocean onto unsuspecting prey located on ice flows, Polar Bears have developed the ability to close their Nostrils, this prevents any unnecessary heat loss when swimming under water.

Threats

The Polar Bear is classified by the IUNCH Red List to be Vulnerable It is believed that there are only 20,000- 25,000 polar bears living in the wild with the IUCN predicting that the Polar ice cap to completely melt within the next 100 years. This will leave the Polar Bears without a habitat and will have a direct negative effect on the Bear population.

Climate change is the most serious threat to Polar Bears with the Arctic warming up twice as much as the global average. Arctic sea ice is a huge white reflector that sits at the top of our planet that bounces some of the sun’s rays back into space that helps keep the Earth at an even temperature. As the sea ice melts, it means there is less surface to reflect the sun’s rays, allowing more heat to be absorbed by the ocean that is magnifying the warming effect. The Arctic is crucial to keep our world’s climate in balance as well as protecting the home of the Polar Bear and four million people. With less Sea ice, this means an increase in shipping traffic that creates more pollution and collisions with wildlife, so much so that the WWF is now working with the Maritime Organisation to find a more safe and environmental friendly way of ships passing through both Arctic and Antarctic waters.

I will let Yorkshire Wildlife Park help me out here

Source: Polar Bears & Climate Change brought to you by Yorkshire Wildlife Park

Published in the journal Ecography, a new study found that polar bears are going to greater lengths to find food that they need. In 2012, up to 70% bears swam up to 49km which shows a 25% rise in the number of bears that covered this distance in 2004. In 2009, a female bear was recorded swimming over 400km over a period of nine days during which she lost her cub who had drowned and she had lost over 20% of her body fat but she somehow managed to survive after finding an ice floe that was sufficient in holding her weight. This has now become a common problem.

Source: A harrowing photograph that may become more common as bears are having a harder time finding food

Human Conflict

As always, we can’t seem to just leave the wildlife alone. With the huge reduction of Sea ice and habitat for the Bear it means they are now venturing into towns and villages in search of food with dangerous consequences for both parties. The WWF is working with local villages to reduce conflict with Bears and fitting transmitting collars to bears to see how they are coping with the changes to the climate.

What you can do to help

Protected zones in the Arctic have doubled between 1991-2010 to 11% from 5.6% that means there are now 1,127 protected areas in the Arctic that covers 3.5 million sq km of land. the WWF is working with regional governments to create a further network of protected areas to help cope with climate change and increased human development.

There are many ways in which you can help Polar Bears and the climate:

• You can vote for the right political representatives that recognise that our carbon footprint is no longer sustainable.
• You can take part in raising awareness of how small lifestyle changes can make a huge difference, you can take part in planting trees, recycling and cycling to work or using public transport more often.
• Reduce your energy usage.
• Encourage your friends to recycle and become more sustainable with turning their lights off when leaving the room.
• Text bear46 £1 to 70070. All proceeds going to help polar bears in the wild.
  You can find more ways here: Further Actions

More Polar Bear Facts

• Polar bears clean themselves in the snow by rolling around
• Polar Bears do not hibernate like others in the Ursid family
• Their nose is so sensitive that they can sense a seal from up to 20 miles away
• When they are not hunting the bear will rest for up to 20 hours per day – Wouldn’t that be nice?

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Amavis Poo Fact

Keepers at Assinboine Park Zoo have been using glitter in the diets of their bears to allow them to track their health and happiness of each bear!

Upon arrival to the zoo, the Polar Bear will be given an assigned non-toxic glitter colour so samples of each individual bears can be collected until they reach sexual maturity that is mixed with their diet. The faecal matter is used to identify current health issues associated with unique Bears and the collection is allowing for researchers to perform a longer study of how Bears acclimate to Zoo life. The sample tracks the stress hormone cortisol levels of the young Bears during their first few months at the Zoo looking for spikes that can indicate to the keepers that they need to change something within the environment. This method of testing hormones is less invasive than blood draws that would require anaesthetising the Bear however this is performed for wild Bears.

This monitoring of hormones and fluctuations of Bears in captivity allows scientists to find particular levels in wild Bears. This method of sampling is widely used in Zoos, in particular with large carnivores to monitor their stress levels in a captive environment and provide researchers and Zoo collections with opportunities to improve welfare for their animals.

Amazing right?

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If we do not reduce our carbon footprints, we will be saying goodbye to the Arctics iconic and amazing animal.

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If you enjoyed this edition of Amazing Animals you may be interested in some of my previous posts:

• Amazing Animals The Blue Whale
• Amazing Animals The Pangolin
• Amazing Animals The Emperor Penguin
• Amazing Animals The Giraffe

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Content sources

1, 2, 3, 4, 5, 6, 7, 8, 9, Journal

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