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Polar Bears - Data, Pictures and Videos
Polar Bears - Data, Pictures and Videos
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Polar Bears - Data, Pictures and Videos
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Photo and information credits: Thomas Mangelsen
"On my last trip to Antarctica, I was fortunate enough to see an incredibly rare Shackleton bear hunting penguins on an iceberg off the Antarctic Peninsula. In the five trips I have made to the bottom of the earth, this was my only sighting of this elusive animal."  *This image is copyright of its original author
  
I think it was part of a project to send polar bears to Antarctica. The Shackleton Bear has a Facebook page of its own, but I don't really support the project.
Penguins must live in the near future as well, instead of being mass-consumed by polar bears. For me, I always associate the polar bear with the northern ice regions, not the southern ice regions. That's why people (and I) always refer to polar bears as "bears of the north."
White-beaked Dolphins Lagenorhynchus albirostris trapped in the Ice and eaten by Polar Bears Ursus maritimus Aars, Andersen, Brenière & Blanc, 2015
A polar bear Ursus maritimus eats a white-beaked dolphin Lagenorhynchus albirostris in the Raudfjorden fjord, on the northwestern coast of the Norwegian archipelago of Svalbard, Norway. Melting sea ice has led to more species venturing further north, they are the new preys for polar bears. Photo credits: Samuel Blanc  *This image is copyright of its original author Fig. 1 A male polar bear Ursus maritimus on the carcass of a white-beaked dolphin Lagenorhynchus albirostris, 23 April 2014. The bear has started to cover the remains with snow. Just to the left of the dolphin is a hole in the ice, assumed to be a breathing hole that dolphins trapped in the ice have kept open.  *This image is copyright of its original author Fig. 3 An adult polar bear Ursus maritimus feeding on the remains of a white-beaked dolphin Lagenorhynchus albirostris in Raudfjorden on 2 July 2014. The dolphin is presumed to be a member of the same pod as the dolphins eaten by a bear in April.  *This image is copyright of its original author Abstract: "Polar bears (Ursus maritimus) depend on sea ice, where they hunt ice-associated seals. However, they are opportunistic predators and scavengers with a long list of known prey species. Here we report from a small fjord in Svalbard, Norwegian High Arctic, a sighting of an adult male polar bear preying on two white-beaked dolphins (Lagenorhynchus albirostris) on 23 April 2014. This is the first record of this species as polar bear prey. White-beaked dolphins are frequent visitors to Svalbard waters in summer, but have not previously been reported this far north in early spring. We suggest they were trapped in the ice after strong northerly winds the days before, and possibly killed when forced to surface for air at a small opening in the ice. The bear had consumed most parts of one dolphin. When observed he was in the process of covering the mostly intact second dolphin with snow. Such caching behaviour is generally considered untypical of polar bears. During the following ice-free summer and autumn, at least seven different white-beaked dolphin carcasses were observed in or near the same area. We suggest, based on the area and the degree to which these dolphins had decayed, that they were likely from the same pod and also suffered death due to entrapment in the ice in April. At least six different polar bears were seen scavenging on the carcasses."
https://books.google.com/books?id=aouJPN...ts&f=false
http://www.bearbiology.com/fileadmin/tpl..._16_1_.pdf To weigh or not to weigh: conditions for the estimation of body mass by morphometry Marc R.L. Cattet1'3 and Martyn E. Obbard2'4 'Canadian Cooperative Wildlife Health Centre, Department of Veterinary Pathology, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, SK S7N 5B4, Canada 2Wildlife Research and Development Section, Ontario Ministry of Natural Resources, PO Box 7000, 300 Water Street, 3rd Floor North, Peterborough, ON K9J 8M5, Canada Abstract: The objective of this study was to define the conditions under which the body mass of polar bears (Ursus maritimus) can be estimated by morphometry with acceptable accuracy (high precision and low bias). Morphometric and body mass values from 563 polar bears captured and handled in southern Hudson Bay during 1984-86 and 2000-03 were analyzed to determine the effects of sample size and time on the accuracy of estimated body mass (EBM) and to determine the effect of using EBM versus observed body mass (OBM) to calculate body condition index (BCI) values. When sample size was small (<25), variation around the difference between OBM and EBM was large. However, precision improved markedly with increasing sample size, stabilizing within approximately 3% for sample sizes > 100. Morphometric-body mass relationships developed for southern Hudson Bay polar bears in the mid-1980s consistently overestimated body masses of bears handled since 2000 by approximately 4%, suggesting relationships within the population had changed over time (increased bias). This was verified by new prediction equations developed for each period that showed the EBM of polar bears captured in 2000-03 is 7-18% less than that for bears captured in the mid-1980s when morphometric values are held constant. Accuracy was reduced when EBM, instead of OBM, was used as a predictor variable for calculation of the BCI. This was caused by both loss of precision and increase in bias as a result of compounding the error associated with the EBM. Although body mass can be estimated accurately by morphometry under specific conditions, we recommend that investigators routinely weigh a proportion of bears captured per field season to ensure and maintain accuracy. The OBM values can be used to both verify the accuracy of EBM values and to calculate BCI values for representative bears. 
Question by Lars: "Does a polar bear drink water when it's out on the sea ice and if so, where does it find it? Living in a frozen world does not supply a lot of liquid fresh water."
Answer by Dr. Thea Bechshoft: Hi Lars, good question! Polar bears do indeed live most of their life out on the sea ice, surrounded by salt water, which is no good for drinking. However, the bears have found a couple of ways to get around this lack of drinking water. The primary way polar bears get their water is – however odd it may sound - by eating as much seal fat as they can lay their paws on. When catching a seal, a polar bear will eat the energy-rich fat (blubber) first, often leaving the meat behind. There are several reasons for this, but one of them – getting back to your question – is that the physiological process of metabolizing meat protein requires water from the body, whereas the breaking down of fat actually releases water. In other words: the more fat the polar bear eats, the less water it will need to drink (if any at all). This holds true regardless of whether the bear is burning recently eaten seal fat or burning its own fat deposits. Polar bears will also sometimes eat snow, but usually not in great quantities as it requires too much energy to melt it. In fact, eating snow tends to be something the bears mainly do when they want to cool down (after sparring or on a sunny day). And finally, I imagine that polar bears will occasionally have a drink or two at the fresh water melt ponds that can form on the sea ice during the warmer months of the year Follow Dr. Thea Bechshoft. at twitter https://twitter.com/BioThea
Photo and information credits: Paul Nicklen Photography
"Bears need ice, period! A large male bear hops up onto a piece of glacier ice that has just calved into the sea in Svalbard, Norway. Seals and walrus are often found resting on these bergie bits and bears like to work the faces of these large glaciers in search of a meal. It is like a sushi conveyor belt for these bears. With that said, 99% of glaciers in the northern hemisphere are receding and many of these glaciers have shrunk to the point that they are on land only, adding no ice back into the marine ecosystem."  *This image is copyright of its original author
Photo and information credits: Marco Gaiotti Photography
"This guy was really close..." Svalbard  *This image is copyright of its original author
http://www.earthtimes.org/nature/brown-bears-versus-polar-bears/93/
The bleak future for polar bears as global warming encourages brown bears to range further north. Something that is not widely realised is that polar bears only evolved as a distinctive species as recently as 200,000 years ago during the Pleistocene. It is believed that today's polar bears are descended from a group of brown bears that became isolated by glaciers in an area near Siberia and underwent a rapid series of evolutionary changes in order to survive and adapt to Arctic life. These involved a change in the colour of their fur, the shape of their body, sharper teeth and large feet with thick, curved, non-retractable claws that are used for grasping prey as well as providing vital traction when running or climbing on ice. Polar Bears are the world's largest land carnivore and the only member of the bear family that is entirely carnivorous. They live on a diet entirely composed of seal flesh and blubber. As a result of this relatively rapid evolution into a semi-aquatic Arctic life with a very specialised diet, the polar bear has developed a cranial morphology that is weaker than that of brown bears and less suited to processing tough omnivorous or herbivorous diets. Polar bears live almost exclusively on the flesh of young ringed or bearded seals. They have 42 teeth and have developed blade-like incisors to shear off pieces of flesh, with strong canine teeth to grasp prey and tear tough hides. Since they swallow most of their food in large chunks rather than chewing it first, strong molars are not necessary and these are much smaller than those of their brown cousins. While their teeth are super-efficient for processing seal flesh and blubber, polar bears' teeth are less suited for processing bones and hard-to-chew diets with lots of vegetation. The polar bear's low, flat skull with its high-sitting eyes is ideal for a semi-aquatic life and it gives them the advantage of being able to thrust their heads into breathing holes or puppy dens. A recent study by the on-line research journal PLoS One (Public Library of Science) says that although the heads and muscle power of polar bears and brown bears are similar, tests reveal that the polar bear's skull is a 'weaker, less work-efficient structure' and does not appear to be well-suited to large amounts of chewing. Although brown bears will eat animals when they are available, they will also eat a large amount of plant material in the summer, which all requires a considerable amount of chewing before it can be swallowed. It is estimated that the world population of polar bears is between 20,000 and 25,000, of which about 60 per cent live in Canada, but the study concludes that as the earth warms and the brown bears continue to range northwards, this is likely to present polar bears with a significant challenge. Where Arctic foxes overlap with red foxes, it is always the red foxes that end up controlling the prime feeding and breeding areas and the fear is that polar bears will share a similar fate.
Here is another awesome information about Polar bear bite force by my favorite Polar bear expert Thea Bechshoft
Question by Andrew: How strong/powerful is a polar bear? Has anyone managed to crunch some numbers? Answer By Dr Thea: Most of what we know about polar bear strength comes from behavioral observations, but more on that later. First: yes, there are in fact a couple of scientific studies on polar bear strength. One study investigated bite force in all bear species and found that polar bears had a marginally stronger bite than the other (extant) bears, mainly due to its generally bigger body size. Also notable, the polar bears’ bite force was still lower than that of other carnivores, e.g. big cats, likely due to differences in prey and evolution. The other study investigated the structural strength of computer modeled polar bear skulls compared to brown bear/grizzly skulls. Results of the computer simulation showed that polar bear skulls were the structurally weaker of the two. However, this is more interesting in regards to evolution that it is to the bears’ everyday lives – skulls are surprisingly elastic, and polar bears mainly eat blubber and other soft foods that offer little resistance. As I mentioned earlier, there are many behavioral observations that add to our knowledge of the strength and power of polar bears. For example, polar bears: 1. can kill with a blow of their dinner-plate sized paw. Also, speaking of hunting, they can easily pull a seal of up to 200-300 kg or even a beluga whale(!) out of the water and drag it along on the sea ice as they wish. This is mainly due to their large jaw muscles as well as the muscles and ligaments that support the head and help them attain an incredible pulling force. 2. specializations which are visible on the skulls if you know what to look for: polar bear skulls have two crests, one along the midline on the top of the skull (the saggital crest) and one across the back of the skull (the occipital crest). The first one is where the large jaw muscles attach; the second one is where the neck muscles and ligaments attach. Both are bigger in males than in females, meaning that males can handle bigger prey. You can just about see them on the skull I am holding in the picture below. 3. the largest polar bear in the collection at the Natural History Museum in Oslo, Norway (where I did my M.Sc. way back when). 4. are incredibly strong swimmers. Longest swim on record is 687 km over the course of 9 days, but swims of an average of 100 km over 3 days are not unusual. The bears can also dive for up to at least 3 min 10 s without surfacing to breathe. 5. can easily tear through cabin walls two of many existing stories: http://news.bbc.co.uk/2/hi/europe/3584210.stm http://wasillaalaskaby300.squarespace.co...r-doo.html  *This image is copyright of its original author
Photo and information credits: Mike Reyfman Photography
"Polar bear walking on an ice floe along Spitsbergen coast. Svalbard, Norway."  *This image is copyright of its original author
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