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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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POLAR BEARS (URSUS MARITIMUS), THE MOST EVOLUTIONARY ADVANCED HIBERNATORS, AVOID SIGNIFICANT BONE LOSS DURING HIBERNATION
Abstract Some hibernating animals are known to reduce muscle and bone loss associated with mechanical unloading during prolonged immobilisation,compared to humans. However, here we show that wild pregnant polar bears (Ursus maritimus) are the first known animals to avoid significant bone loss altogether, despite six months of continuous hibernation. Using serum biochemical markers of bone turnover, we showed that concentrations for bone resorption are not significantly increased as a consequence of hibernation in wild polar bears. This is in sharp contrast to previous studies on other hibernating species, where for example, black bears (Ursus americanus), show a 3-4 fold increase in serum bone resorption concentrations posthibernation,and must compensate for this loss through rapid bone recovery on remobilisation, to avoid the risk of fracture. In further contrast to black bears, serum concentrations of bone formation markers were highly significantly increased in pregnant female polar bears compared to non-pregnant,thus non-hibernating females both prior to and after hibernation. However, bone formation concentrations in new mothers were significantly reduced compared to pre-hibernation concentrations. The de-coupling of bone turnover in favour of bone formation prior to hibernation, suggests that wild polar bears may posses a unique physiological mechanism for building bone in protective preparation against expected osteopenia associated with disuse,starvation, and hormonal drives to mobilise calcium for reproduction, during hibernation. Understanding this physiological mechanism could have profound implications for a natural solution for the prevention of osteoporosis in animals subjected to captivity with inadequate space for exercise,humans subjected to prolonged bed rest while recovering from illness, or astronauts exposed to antigravity during spaceflight.© 2008 Elsevier Inc. All rights reserved. ... The bear gets its energy from stored fats, and muscle mass is not lost, but renewed ( Lohuis et al., 2007). The products of catabolism, such as urea, are not excreted but recycled ( Nelson et al., 1975;Floyd et al., 1990; Barboza et al., 1997) and the bone tissue does not suffer losses but is actively remodelling (Donahue et al., 2006;Lennox and Goodship, 2008;McGee et al., 2008), although at a lower rate than during the active season. During hibernation the synthesis of proteins is made from the ni- trogen compounds produced thanks to the recycling of the reab- sorbed urea. ... ... In conclusion, we provide both in vivo and in vitro evidence supporting the expression of circadian rhythms in bears during winter dormancy. These findings, along with earlier work in grizzly bears [64] and polar bears add to the mounting evidence that these closely related species may exhibit an evolutionarily advanced form of torpid biology [65, 66]. ... https://www.researchgate.net/publication/5603402_Polar_bears_Ursus_Maritimus_the_most_evolutionary_advanced_hibernators_avoid_significant_bone_loss_during_hibernation/amp (07-02-2014, 12:16 AM)Pckts Wrote: I am sure the bear in second photo was much smaller than 2210 pounds bear
A starving bear that wandered in June to Norilsk City, Krasnoyarsk Krai, Russia, which is hundreds of kilometers to the south of the bear's natural habitat: https://www.independent.ie/world-news/st...32177.html
Credit: Irina Yarinskaya / Zapolyarnaya Pravda / Reuters  *This image is copyright of its original author  *This image is copyright of its original author Credit: Vyacheslav Yarinskiy / Reuters  *This image is copyright of its original author Coincidentally, the polar bear is featured in the city's flag and coat-of-arms: https://vector-images.com/image.php?epsid=720, https://vector-images.com/image.php?epsid=721  *This image is copyright of its original author  *This image is copyright of its original author
I read some news which was shocking recently and it involved polar bears. So, a professor Susan Crockford claimed that “the result of her research showing that polar bear populations are stable and even thriving, not plummeting as a result of shrinking Arctic sea ice, defying claims of the climate change movement.”
Now the controversy surrounds the fact that she was kind of terminated and her insinuation is that is because her research did not push the climate catastrophe narrative. Of course this case has more to do with freedom of expression versus pushing a narrative especially in academia. But, the polar bear part stuck out because she has also worked with PBS on some documentaries (it was about dogs). https://www.washingtontimes.com/news/2019/oct/20/susan-crockford-fired-after-finding-polar-bears-th/ (10-29-2019, 08:57 PM)Ashutosh Wrote: I read some news which was shocking recently and it involved polar bears. So, a professor Susan Crockford claimed that “the result of her research showing that polar bear populations are stable and even thriving, not plummeting as a result of shrinking Arctic sea ice, defying claims of the climate change movement.” If that University thinks that this move of theirs won't backfire, then they're mistaken. As it is, the news picked it up, and you know how things can spread in the media.  (10-29-2019, 08:57 PM)Ashutosh Wrote: I read some news which was shocking recently and it involved polar bears. So, a professor Susan Crockford claimed that “the result of her research showing that polar bear populations are stable and even thriving, not plummeting as a result of shrinking Arctic sea ice, defying claims of the climate change movement.” Yet recently there have been claims that polar bear populations are increasing. So what’s going on? There are thought to be between 20,000 and 25,000 polar bears in 19 population groups around the Arctic. While polar bear numbers are increasing in two of these populations, two others are definitely in decline. We don’t really know how the rest of the populations are faring, so the truth is that no one can say for sure how overall numbers are changing. The two populations that are increasing, both in north-eastern Canada, were severely reduced by hunting in the past and are recovering thanks to the protection they and their prey now enjoy. The best-studied population, in Canada’s western Hudson Bay, fell by 22% from 1194 animals in 1987 to 935 in 2004, according to the US Fish and Wildlife Service. A second group in the Beaufort Sea, off Alaska’s north coast, is now experiencing the same pattern of reduced adult weights and cub survival as the Hudson Bay group. A comprehensive review (pdf) by the US Fish and Wildlife Service concluded that shrinking sea ice is the primary cause for the decline seen in these populations, and it recently proposed listing polar bears as threatened (pdf) under the Endangered Species Act. The World Conservation Union projects the bears’ numbers will drop by 30% by 2050 (pdf) due to continued loss of Arctic sea ice. Read more: https://www.newscientist.com/article/dn11656-climate-myths-polar-bear-numbers-are-increasing/#ixzz63lLe2TBi  *This image is copyright of its original author https://arcticwwf.org/species/polar-bear/population/ (10-29-2019, 08:30 PM)BorneanTiger Wrote: A starving bear that wandered in June to Norilsk City, Krasnoyarsk Krai, Russia, which is hundreds of kilometers to the south of the bear's natural habitat: https://www.independent.ie/world-news/st...32177.html Did anyone notice that polar bears can be visibly yellow, white, or in-between, like the Russian bear above? Yellow bear by M. Watson White sow near Kaktovik, Barter Island, Alaska; credit: Alan Wilson
Group of polar bears attacking walruses: https://www.youtube.com/watch?v=YFAtQB0q_j0
Polar bears and salmon: https://www.youtube.com/watch?v=9m_Q9Ojbcmw Eating a dolphin, a new phenomenon which scientists blame on climate change: https://www.dailymail.co.uk/sciencetech/...nning.html Credit: AFP With their grizzly cousins at a whale's carcass in Alaska, credit: Steven Kazlowski / Science Faction / Corbis
Polar bears trying their luck at a skill at which their grizzly cousins to the south are professionals, that is catching salmon:
Group of bears attacking walruses, leading to a massacre of pups: Power of the polar bear: 
" Polar bear eating a dolphin. Due to the Arctic Ocean being warmer than usual dolphins had made their way north far sooner than previous years giving this polar bears some more options on the menu. ".
(11-27-2019, 11:28 AM)Spalea Wrote: " Polar bear eating a dolphin. Due to the Arctic Ocean being warmer than usual dolphins had made their way north far sooner than previous years giving this polar bears some more options on the menu. ". Same picture as what I posted above, but different medium. Ihis is in Instagram, whereas what I posted was from a newspaper.
@BorneanTiger :
About #177: " Same picture as what I posted above, but different medium. Ihis is in Instagram, whereas what I posted was from a newspaper. ". OK, the next times I will look for the source beyond "reall_nature" or other pictures providers like this one on Instagram. As for me, it was the first time I saw this photo. (10-29-2019, 08:30 PM)BorneanTiger Wrote: A starving bear that wandered in June to Norilsk City, Krasnoyarsk Krai, Russia, which is hundreds of kilometers to the south of the bear's natural habitat: https://www.independent.ie/world-news/st...32177.html Who in Russia did this to the state animal of Norilsk City? https://www.bbc.com/news/world-europe-50643315, edition.cnn.com/2019/12/04/asia/russian-polar-bear-t-34-spray-paint-intl-hnk-scli/index.html, https://globalnews.ca/news/6253038/polar-bear-graffiti/, https://www.theguardian.com/environment/...ssia-video  |
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