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Post by OldGreenGrolar on Dec 23, 2020 9:45:43 GMT -5
Another significant difference between the species are their skulls, which, while similar in size, vary greatly in bite force and bone strength. The polar bear has a stronger bite, but a weaker skull. Polar bears are one of the most rapid instances of evolution in surviving species of animals, having evolved from the grizzly bear within the last five hundred thousand years. So why are their skulls weaker if their bite is stronger?
From the same link in reply 70.
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Post by OldGreenGrolar on May 4, 2021 9:03:48 GMT -5
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Post by brobear on May 4, 2021 9:10:28 GMT -5
Reply #81 - polarbearsinternational.org/news/article-polar-bears-international/polar-bear-body-condition-index/ Polar Bear Body Condition Index. Can you tell how healthy a polar bear is just by looking at it? How do you describe how fat or skinny a bear is? Polar Bears International, in collaboration with partners, has developed a Body Condition Index card to help answer those questions. Bears need stored fat to survive and reproduce, and fat is indicative of overall health and condition. It's hard to quantify how much fat a bear has in the field without handling the animal and having the right technology at hand. That's where the Body Condition Index card comes into play. It provides a standardized way to rate bears in the field through visual observation, and in some cases palpation, or touch (if they are safely sedated). Over time, records of body condition across years and regions will help us monitor individual condition, as well as how broader populations may be affected by large-scale environmental change, including loss of sea ice due to climate change. The original project was conceived by Polar Bears International (PBI) volunteer Diana Weinhardt and completed in conjunction with Dr. Steven Amstrup and Geoff York, now with PBI, when they worked for the U.S. Geological Survey in 2007. After hearing suggestions on how to improve the card over the ensuing years, York led an effort to revise it in 2015. The Body Condition Index is based on veterinary body condition cards common for livestock and domestic pets and informed by a paper on body condition by Ian Stirling, Gregory W. Thiemann, and Evan Richardson. In the abstract to the paper, Quantitative Support for a Subjective Fatness Index for Immobilized Polar Bears (Journal Of Wildlife Management, January 2008), the researchers wrote, "Our data demonstrate that the FI (fatness index) rating accurately reflects overall body condition, regardless of polar bear age, sex, or nutritional phase. We suggest that continued field use of the FI rating could provide valuable information on ecological effects of large-scale environmental change on polar bear populations." York worked with wildlife illustrator Emily Damstra and a team of volunteer advisors from the IUCN Polar Bear Specialist Group in revising the card. They used photographs of wild bears from several regions and in various body conditions to refine the illustrations. The initial audience was research scientists in the field—the index helped ensure that everyone was using the same criteria to assess polar bears across their range. That audience has grown and now the card is used by hunters, polar bear deterrence staff, Arctic workers, Arctic visitors, and is available for use by Arctic residents. PBI will use the card in our Body Condition Project—a program to gather information on the body condition of polar bears during the Western Hudson Bay migration each fall. To the back of the card, PBI added a bear safety primer. "The bear-safety aspect targets visitors to polar bear country as part of our ongoing efforts to reduce bear human conflict," York said. "We have also made the revised BCI card available to government partners for use in their own outreach efforts and under their own logos." In areas where polar bears are still legally harvested by Arctic peoples, many governments collaborate with hunters to obtain biological samples and other information, such as body condition, from harvested animals. The BCI card is also useful for people working or recreating in polar bear country in an effort to provide more significant information to bear encounter reports. Body Condition Index card collaborators and advisors Geoff York, Polar Bears International Steven Amstrup, Polar Bears International Andrew Derocher, University of Alberta Martyn Obbard, Ontario Ministry of Natural Resources and Forestry Todd Atwood, U.S. Geological Survey Eric Regehr, U.S. Fish and Wildlife Service Kristin Laidre, University of Washington Ian Stirling, University of Alberta Gregory W. Thiemann, York University Evan Richardson, Environment Canada
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Post by brobear on May 4, 2021 9:12:17 GMT -5
*Note: nowhere in replies #81 and #82 am I reading that even a 'very fat' polar bear is in bad health due to his fat condition.
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Post by OldGreenGrolar on May 4, 2021 9:44:04 GMT -5
*Note: nowhere is replies #81 and #82 am I reading that even a 'very fat' polar bear is in bad health due to his fat condition. Polar bears have the bone structure to sustain massive obesity. A fat bear is a healthy bear indeed.
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Post by brobear on Aug 29, 2021 3:57:36 GMT -5
www.ncbi.nlm.nih.gov/pmc/articles/PMC2974639/ Biomechanical Consequences of Rapid Evolution in the Polar Bear Lineage. Abstract The polar bear is the only living ursid with a fully carnivorous diet. Despite a number of well-documented craniodental adaptations for a diet of seal flesh and blubber, molecular and paleontological data indicate that this morphologically distinct species evolved less than a million years ago from the omnivorous brown bear. To better understand the evolution of this dietary specialization, we used phylogenetic tests to estimate the rate of morphological specialization in polar bears. We then used finite element analysis (FEA) to compare the limits of feeding performance in the polar bear skull to that of the phylogenetically and geographically close brown bear. Results indicate that extremely rapid evolution of semi-aquatic adaptations and dietary specialization in the polar bear lineage produced a cranial morphology that is weaker than that of brown bears and less suited to processing tough omnivorous or herbivorous diets. Our results suggest that continuation of current climate trends could affect polar bears by not only eliminating their primary food source, but also through competition with northward advancing, generalized brown populations for resources that they are ill-equipped to utilize.
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Post by OldGreenGrolar on Sept 2, 2021 7:58:19 GMT -5
Sooner or later a male polar bear will eventually kill a much smaller barren ground grizzly.
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Post by OldGreenGrolar on Sept 4, 2021 10:01:14 GMT -5
THE POLAR BEAR IS THE MOST UNPREDICTABLE OF ALL BEARS. ITS HIDE IS TOO THICK TO FEEL HEAVY BLOWS. WHEN FACED WITH SOMETHING UNFAMILIAR SOME ANIMALS DISPLAY A STREAK OF COWARDICE, BUT NOT SO THE POLAR BEAR. WHEN IT LUNGES AT AN INTERLOPING OBJECT IT SEEKS TO DESTROY IT. . Male polar bears fight to death during mating season. The account above proves their durability.
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Post by OldGreenGrolar on Sept 5, 2021 3:52:29 GMT -5
Male. Female. Pregnant female. Credited to Taker.
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Post by OldGreenGrolar on Sept 13, 2021 21:39:30 GMT -5
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Post by OldGreenGrolar on Sept 14, 2021 0:59:30 GMT -5
Polar bears genders are fairly easy to distinguish especially because of their sexual demorphism.
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Post by OldGreenGrolar on Sept 18, 2021 9:14:52 GMT -5
Do polar bears have strong teeth? They are designed to allow the Polar Bear a way to easily dig and to scoop the ice. Polar Bears have a mouth full of 42 extremely sharp teeth. Since they are carnivorous, they need them to kill their prey as well as to consume it. Their teeth are longer and sharper than those of the Brown Bear. www.polarbear-world.com/polar-bear-anatomy/
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Post by OldGreenGrolar on Sept 18, 2021 9:22:02 GMT -5
Body Type.Polar bears have a heavy stout body with strong muscular legs and well-developed neck muscles. Compared to other bears, the head of a polar bear is proportionally smaller. The necks of polar bears are longer than their nearest kin, the brown bear. This adaptation makes it easier for them to keep their heads above water when swimming. They have short, fur covered ears and a very short tail. Polar bears have large paws compared to body size, reaching 30 cm (12 in.) in diameter. The large paws of a polar bear act like snowshoes, spreading out the bear's weight as it moves over ice and snow. The forepaws are round, and the hind paws are elongated. The partial webbing between their toes, polar bears are able to use their front feet much like paddles to propel them rapidly through the water. The hind feet are slightly smaller. On both the front and hind feet, the bottoms are covered with dense fur, which affords better traction when moving on ice. Each toe has a thick, curved, nonretractable claw. The claws are used for grasping prey and for traction when running or climbing on ice. The sole of a polar bear's foot has thick, black pads covered with small, soft papillae (dermal bumps). The papillae create friction between the foot and ice to prevent slippage. Long hairs growing between pads and toes also help prevent slippage. Polar bears walk in a plantigrade manner (i.e., in a manner similar to humans with both heel and toe make contact with the ground when walking). On land, they are not as quick as brown bears and appear to have traded off speed for their extremely massive forelegs which they use to break through seal dens or flip a large seal out of the water. They are able to attain speeds of 40 kilometers per hour (25 miles per hour) for short distances. myweb.facstaff.wwu.edu/~brilla/PBear.htm
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Post by OldGreenGrolar on Sept 18, 2021 9:27:39 GMT -5
Hibernation
Hibernating means to pass the winter in a dormant or lethargic state. Animals that hibernate store body fat when food is plentiful. When food is scarce, they hibernate, living off their stored body fat. Polar bears do not enter deep hibernation. Deep hibernation applies to an animal whose body temperature drops to 5C (41F) for a period of days or weeks. Deep hibernators also show a marked drop in heart rate, and are slow to wake up when disturbed. Only pregnant female polar bears hibernate. Polar bears are not deep hibernators, but enter a state of carnivore lethargy. Though hibernating females sleep soundly, they are easily and quickly aroused. The female polar bear's heart rate slows to about (8-12 bpm at a low) 27 beats per minute from a normal resting heart rate of about 46 beats per minute.When hibernating, a female's body temperature may drop slightly, perhaps to 35C (95F), or it may remain normal at 37C (98.6F). Unlike many other animals who hibernate, its body temperature only undergoes a minor reduction of 3 to 7 degrees Centigrade (5 to 9 degrees Fahrenheit). Its metabolism slows down by half. Unlike most other hibernators, female polar bears give birth while hibernating. High body temperature is needed to meet the demands of pregnancy, birth, and nursing. Researchers have found that nonhibernating polar bears, during times of food scarcity, can efficiently utilize their energy reserves much like hibernating bears. During the period of hibernation, the polar bear will neither pass urea or solid fecal waste. While urea poisoning causing death would occur in all other animals within a week, bears have developed a unique process of recycling the urea into usable proteins. During the hibernation period, all bears lose a great deal of weight. It is not uncommon for a female polar bear with newborn cubs to lose as much as 40% of her weight. myweb.facstaff.wwu.edu/~brilla/PBear.htmJudging from the sentence underline, it shows that polar bears with 50% fat are pregnant females.
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Post by brobear on Sept 20, 2021 2:17:36 GMT -5
Reply #92: On land, they are not as quick as brown bears and appear to have traded off speed for their extremely massive forelegs which they use to break through seal dens or flip a large seal out of the water. *Polar once stated that a polar bear has more massive arms ( forelimbs ) than a brown bear of equal size.
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Post by OldGreenGrolar on Sept 20, 2021 4:06:37 GMT -5
Reply #92: On land, they are not as quick as brown bears and appear to have traded off speed for their extremely massive forelegs which they use to break through seal dens or flip a large seal out of the water. *Polar once stated that a polar bear has more massive arms ( forelimbs ) than a brown bear of equal size. Polar bears appear to have more massive arms and bigger paws even at equal weight. However, the brown bear had the better shoulder hump and body. Polar bear also has thicker fur.
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Post by OldGreenGrolar on Sept 20, 2021 11:12:34 GMT -5
850 lb coastal grizzly/Kodiak bear and an 850 lb Svalbard polar bear: Credited to Taker and reposted by King Kodiak.
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Post by brobear on Sept 20, 2021 14:42:14 GMT -5
As you stated in post #95; polar bear has longer/bigger arms while the brown bear has broader skull, bigger-shorter neck, and more massive shoulders. Chest musculature?
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Post by OldGreenGrolar on Sept 20, 2021 17:32:30 GMT -5
As you stated in post #95; polar bear has longer/bigger arms while the brown bear has broader skull, bigger-shorter neck, and more massive shoulders. Chest musculature? I am betting on the brown bear too but the polar bear’s is not too far behind.
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Post by OldGreenGrolar on Oct 17, 2021 6:41:43 GMT -5
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