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Sept 4, 2011 16:52:09 GMT -9
Post by grrraaahhh on Sept 4, 2011 16:52:09 GMT -9
Genetic structure of the world’s polar bear populationsAbstract We studied genetic structure in polar bear (Ursus maritimus) populations by typing a sample of 473 individuals spanning the species distribution at 16 highly variable micro-satellite loci. No genetic discontinuities were found that would be consistent with evolutionarily significant periods of isolation between groups. Direct comparison of movement data and genetic data from the Canadian Arctic revealed a highly significant correlation. Genetic data generally supported existing population (management unit) designations, although there were two cases where genetic data failed to differentiate between pairs of populations previously resolved by movement data. A sharp contrast was found between the minimal genetic structure observed among populations surrounding the polar basin and the presence of several marked genetic discontinuities in the Canadian Arctic. The discontinuities in the Canadian Arctic caused the appearance of four genetic clusters of polar bear populations. These clusters vary in total estimated population size from 100 to over 10 000, and the smallest may merit a relatively conservative management strategy in consideration of its apparent isolation. We suggest that the observed pattern of genetic discontinuities has developed in response to differences in the seasonal distribution and pattern of sea ice habitat and the effects of these differences on the distribution and abundance of seals. www.biology.ualberta.ca/faculty/andrew_derocher/uploads/abstracts/Paetkau_et_al_1999.pdf
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Sept 4, 2011 16:52:59 GMT -9
Post by grrraaahhh on Sept 4, 2011 16:52:59 GMT -9
Counting Black Polar BearsThe white winter camouflage of many birds and mammals such as the ptarmigan, the Arctic hare and the harp seal (as a pup) serves to protect them against predators. The polar bear scarcely needs such protection, and one might wonder why nature chose to provide it--until it is considered that a sneaking white polar bear cannot be easily seen by a sunbathing seal. In any case, to biologists who are concerned with keeping track of animal populations, such camouflage can be frustrating. These animals often live in areas (such as on ice packs) where aerial counts are feasible because of the lack of overhead cover, but ordinary photographic means do not easily distinguish white animals against a white background. Zoologists D. Lavigne and N. Oritsland of Ontario tried using thermal infrared imagery as a means of detection (this is one of the methods used by border patrols to catch illegal aliens during the hours of darkness), but they found that in cold and windy conditions, sufficient temperature differences did not exist between a well-insulated animal and its environment to enable them to identify the animals. However, it was found that photography at the other end of the spectrum--the ultraviolet--did. Infrared and ultraviolet are both invisible to our eyes, but most film emulsions are sensitive to them. The coat of a polar bear or a harp seal pup reflects all wavelengths in the visible spectrum, and thus appears white to the human eye. The same applies to a snow field. However, while the snow also reflects ultraviolet (which explains why it's so easy to get a sunburn while skiing), an animal's coat absorbs it. This being the case, harp seal or polar bear census counts on the ice are simplified by utilizing aerial ultraviolet photography. If a lens filter is used that screens out the visible spectrum and transmits the ultraviolet, the animals look black against a white background in the picture! As a measure of the effectiveness of the technique, Lavigne and Oritsland compared the numbers of harp seal pups detected with ordinary photography and ultraviolet in the same area of the North Atlantic. Black and white picked up only 21 percent of the pups seen on the ultraviolet. The authors also make the observation that ultraviolet photography of military equipment camouflaged white was as revealing as their photography of the white mammals. They recommend a change of paint to something with a high ultraviolet reflectivity. www.gi.alaska.edu/ScienceForum/ASF7/799.html
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Sept 4, 2011 16:53:44 GMT -9
Post by grrraaahhh on Sept 4, 2011 16:53:44 GMT -9
Polar bears of the past survived warmth An ancient jawbone has led scientists to believe that polar bears survived a period thousands of years ago that was warmer than today. Sandra Talbot of the USGS Alaska Science Center in Anchorage was one of 14 scientists who teamed to write a paper based on a polar bear jawbone found amid rocks on a frigid island of the Svalbard Archipelago. The scientists determined the bear was an adult male that lived and died somewhere between 130,000 to 110,000 years ago, and that bear was similar to polar bears today. Charlotte Lindqvist of the University at Buffalo in New York was the lead author on the paper, published in the March 2010 issue of the Proceedings of the National Academy of Sciences. An Icelandic researcher in 2004 found a fossilized lower jawbone, in excellent condition and complete with a canine tooth, on a narrow spit of land on the far west edge of Norway’s Svalbard Archipelago. It was a stunning find because there aren’t many fossils of polar bears around. The largest bears in the world spend most of their lives on sea ice, so they often die there, and their remains either sink or get scavenged by something else. With bone and tooth in hand, scientists got to work with the latest techniques for finding the age of formerly living creatures and determining their genetic backgrounds. The latter is the specialty of Sandra Talbot. She is a research wildlife geneticist who earned her doctorate degree at the University of Alaska Fairbanks by helping determine that the mitochondrial DNA of brown bears on Admiralty, Baranof and Chichagof islands of Southeast Alaska is more closely related to that of polar bears than to the DNA of other brown bears. Talbot says the evidence of a polar bear from 130,000 years ago shows that the creatures somehow survived conditions warmer than they face today. “This is verifying that the polar bear lived through at least one warming period,” Talbot says. “The Eemian was a very hot period, and polar bears survived it,” she says. During the Eemian, about 125,000 years ago, the planet was warm enough that hippos lived where London is now. Polar bears, now adapted to eating seals that live only near sea ice, somehow made it through a few thousand years when there may not have been much sea ice, if any existed at all. “It gives us hope that they survived that stage,” Talbot says. “It does make you think about refugia more.” “Refugia” are places that polar bears may survive without ice. The Svalbard Archipelago may have been one of those places. Biologists today think polar bears would have a difficult time living on land, because other species like the grizzly bear could outcompete them. The warm period of the Eemian might have come at a time when the polar bear wasn’t such an ice specialist, Talbot says. “We can’t predict whether the polar bear is too far out (in its evolution towards a life on ice),” she says. “It’s interesting that there are a few examples of hybridization (between polar bears and brown bears). That’s something worth watching.” And maybe polar bears have been trying to adapt to life on land, but one species has blocked that avenue of evolution. Polar bears that wander onto land, especially near a human settlement, tend to get shot. And humans — who didn’t wander out of Africa until about 45,000 years ago — weren’t present on the edge of the sea ice when polar bears first made it their home. “We weren’t impacting them then the way we are now,” Talbot says. Though the polar bear perhaps prospered through hot times in the past, what they have in store ahead may be their greatest challenge ever. “We’re going into a very similar period of time, but it’s generally thought that this is going to be warmer than (the last great warm period),” Talbot says. www.gi.alaska.edu/ScienceForum/ASF20/2018.html
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Sept 4, 2011 16:54:36 GMT -9
Post by grrraaahhh on Sept 4, 2011 16:54:36 GMT -9
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Sept 4, 2011 16:55:09 GMT -9
Post by grrraaahhh on Sept 4, 2011 16:55:09 GMT -9
View of a polar bear paw. See how big it appears. It can measure over 30 cm. Notice the big toes beneath the abundant fur, but no trace of claws. The grizzly bear and the polar bear have about the same size of paw. The difference lies in the amount of fur beneath the paw and the length of their claws. www.museevirtuel-virtualmuseum.ca/edu/ViewLoitDa.do?method=preview&lang=EN&id=1224Big BearsThe latest news from Deadhorse is that it's been warm (-ish, for Deadhorse in October this means high temperatures in the mid-30s) and we've been catching plenty of bears. Not just any old bears mind you, but big bears. Several days ago we captured a female bear that weighed 820lbs, pretty dang big for a female. The fat layer over her rump was almost 6 inches deep. Take out a tape measure and imagine what it would feel like to have your body covered in that! We also captured a male two days ago that weighed over 1000 lbs[....] I think one of the coolest things about polar bears is the size of their paws. This is a picture of the front right paw of the big male. I'm told that polar bears can walk on thinner ice than a human can, in part because these large paws distribute weight over a greater surface area. scienceposse-cotton.blogspot.com/2009/10/big-bears.html
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Post by warsaw on Nov 6, 2011 1:39:50 GMT -9
Cree understanding of wabusk: documenting traditional knowledge of polar bears in the Hudson Bay Lowlands of Ontario Kakekaspan, Matthew1(mkakekaspan@knet.ca), M. Dowsley2, T. Miles1 , H. Lemelin2, B. Walmark3 and F. Seibel3 1 Washaho Cree Nation at Fort Severn, Fort Severn, Ontario, P0V 1W0 2 Centre for Northern Studies, Lakehead University, Thunder Bay, Ontario, P7B 5E1 3 Keewaytinook Okimakanak Research Institute (KORI), Thunder Bay, Ontario, P7B 3C2 Objectives Few people recognize that the Cree (or the Muskekowuck Athinuwick) of the Hudson Bay Lowlands have interacted with the polar bear (Wabusk, Ursus maritimus) for centuries. As a people exploiting a ecological transition zone between the boreal forest and tundra, as well as the muskeg and the coast, the Muskekowuck Athinuwickhave a considerable store of traditional knowledge about an environment relatively little explored by science. Presented next are the results of a collaborative research project between the First Nations of Washaho and Weenusk, the Keewaytinook Okimakanak Research Institute (KORI), and the Centre for Northern Studies at Lakehead University. The goal of the project was to acquire a greater understanding of Cree knowledge regarding wabusk (polar bear), document human-polar bear interactions in the territories of the Weenusk and Washaho Cree nations of Ontario, and emphasize the political aspects of knowledge production. This presentation discusses the key findings and recommendations from the study. Methods Through collaborative studies aimed at recording Kiskayndamowin/Cree Knowledge, we have since 2006, conducted over 46 interviews with Elders’ and hunters’ experiences with polar bears along the Hudson Bay coast of Northern Ontario. Results Cree knowledge agrees with much information previously published in the scientific literature and adds to it, for example through observations of polar bears preying on beavers, interacting with black bears, and travelling greater distances into the muskeg than previously recorded. Our research suggests that traditional knowledge can serve as a qualitative check on scientific information and extend the recorded knowledge of polar bears.
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Post by warsaw on Nov 6, 2011 1:42:18 GMT -9
Combining Inuit ecological knowledge and western science in wildlife governance: the case of polar bear co-management in Nunavut Henri, Dominique1 (dominique.henri@ouce.ox.ac.uk) and E. Peacock2 1 Oxford University Centre for the Environment, University of Oxford, South Parks Road, OX1 3QY, Oxford, United Kingdom 2 US Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK 99508, USA Given the significance of polar bears for both northern aboriginal people and the global public, there has been growing support for the complementary use of both traditional ecological knowledge (TEK) and scientific information in polar bear research and management, especially in Canada. While collaborative attempts using both science and aboriginal TEK in wildlife governance have extended over the years, the acceptance of their combined use remains contentious. Drawing theoretical insights from the disciplines of ecological anthropology and science and technology studies, we review research and management initiatives that have sought to combine Inuit TEK and scientific information for managing polar bears in Nunavut, Canada. We aim to (1) advance understanding of the challenges and opportunities posed by such an approach; (2) identify potential areas of convergence between scientific expertise and Inuit TEK; and (3) explore mutually affirming ways in which resource users, biologists, and policy-makers can work together. Based on interviews conducted with Inuit, biologists and wildlife managers over the course of 10 months of field research, we argue that while Inuit can bring significant contributions to polar bear governance, the process of integrating Inuit TEK and western scientific knowledge in co-management in Nunavut has faced numerous challenges, including: (1) a lack of transparency and communication between local, scientific and managerial communities regarding the strengths and limitations of TEK and scientific knowledge; (2) the challenge of finding culturally relevant ways of assessing the validity of knowledge rooted in multiple cultural traditions; and (3) the existence of mistrust and power struggles among stakeholders, which hinders the building of collaborative research and management. We suggest that neither science nor TEK is sufficient in isolation for understanding the complexities of polar bear ecology, especially in the context of climate change. We explore ways in which such perspectives can enter a constructive dialogue.
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Nov 7, 2011 10:32:59 GMT -9
Post by warsaw on Nov 7, 2011 10:32:59 GMT -9
An Inuit hunter skins a polar bear that starved to death
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Post by warsaw on Dec 4, 2011 1:05:09 GMT -9
"...In most areas, polar bear diets were dominated by ringed seals, but in the eastern Arctic bears fed primarily on harp seals. Some individuals fed substantively on other prey including bearded seal (Erignathus barbatus), beluga whale (Delphinapterus leucas), and walrus. Diets were generally similar within broad geographic regions (e.g., within the Hudson Bay–Foxe Basin complex), but also showed some variability at finer spatial scales. Diets differed significantly between bears of different age and sex classes, with large adult males being the primary consumers of bearded seal and walrus. Polar bear diets differed among years, especially in Western Hudson Bay and Davis Strait, apparently in response to bottom-up food web effects likely associated with climate change (see Thiemann et al. 2008b)..." pbsg.npolar.no/export/sites/pbsg/en/docs/PBSG15proc.pdf
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Apr 6, 2014 12:44:20 GMT -9
Post by warsaw on Apr 6, 2014 12:44:20 GMT -9
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