Why Less Summer Ice Increases Bear Populations

This image shows the Arctic as observed by the...

This image shows the Arctic as observed by the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) aboard NASA’s Aqua satellite on September 16, 2007. The image shows a record sea ice minimum in the Arctic. (Photo credit: Wikipedia)

Guest essay by Jim Steel, Director Emeritus, San Fransisco State University

“Annual primary production in the Arctic has increased yearly … Should these trends continue, additional loss of ice during Arctic spring could boost productivity >3-fold above 1998–2002 levels” -Dr. Kevin Arrigo, Stanford University

While the Inuit argue it is the time of the most polar bear, CO2 advocates suggest they may soon go extinct, implying the loss of thick, multiyear ice in September is denying the polar bears the icy platform from which they hunt seals. In reality, less summer ice has a negligible effect on normal hunting, but a decisively positive effect on the bears’ main prey. Recent periods of more open water in the summer have undeniably benefitted the whole food chain.

The bears’ most important feeding period extends from March to June when bears binge on breeding ringed seals and their pups. This is the time when hunting on sea ice is most important, but unlike the highly publicized reductions in September ice, the reduction in springtime ice has been quite minor and no respectable models predict the disappearance of winter ice. Without the sun, winter air temperatures range from ‑15°F and ‑52°F and ample ice will always form, providing ringed seals with ample breeding habitat

The Arctic Ocean is relatively poor in nutrients, and benefits greatly from ocean cycles that import nutrients from the Bering Sea and the Atlantic. The intruding warm and nutrient-rich currents also cause less ice, which promotes more photosynthesis. Between 2003 and 2007, productivity in the Arctic Ocean increased by 23% relative to the 1998-2002 average. When phytoplankton increase, zooplankton flourish, treating whales, sea birds and young Arctic cod to a bountiful feast.2 In addition to more food, the warmer surface temperatures stimulate the “cold-blooded” Arctic cod grow faster and bigger, and bigger fish are better able to survive the winter. Fishery scientists have concluded, “at least in the short term, the lengthening of the ice-free season presently observed in Arctic seas could result in improved recruitment and larger populations of Arctic cod.”3

More Arctic cod sustains more ringed seals, harp seals, harbor seals, beluga whales and several species of seabirds. Ringed seals feed intensively on cod in the open waters of summer in order to store the fat needed to survive the winter. Ringed seals suffer when sea ice is slow to break up. In 1992 when breakup of sea ice was delayed by 25 days, the body condition of all ringed seals declined.4 In contrast during the most recent decade with more open water, the number of ringed seal pups in the western Hudson Bay tripled relative to the 1990s.4 With more seal pups the polar bears’ body condition also improved. Polar bear experts observed that recent improvement in the bears’ body condition but never published it.5 Instead papers that try to portray the bears as starving, only report the cycle of decline up to 1999.14

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Ringed Seal Biology

Because a larger body size conserves heat more efficiently, animals living in polar regions are typically the largest among related species. (i.e., polar bears and Emperor penguins) Paradoxically, the ringed seal is the smallest yet most abundant of all Arctic seals, and they remain in the Arctic all winter. Both males and females are featherweights (weighing in at about 110-150 pounds) compared to the male Pacific walrus (weighing in at approximately 3500 pounds). The secret to this tiny seal’s success is the relative warmth of the ocean’s water (+28°F or higher). Seals avoid deadly -20°F air temperatures by staying in the water. In fact, for most of the year, ringed seals spend more than 90% of their time swimming, inaccessible to polar bears.6 Even during the winter when seals are tethered to their breathing holes, they never spend more than 20% of the time out of the water. Although all polar bears (except those that are nursing newborn cubs) remain active during the winter hunting on thick winter ice, the bears continue to lose weight because the odds are slim that they will stumble upon a resting seal.

However, the bear’s odds improve mightily during seals’ breeding season. For about 6-8 weeks from late March through May, adult ringed seals spend about 50% of their time hauled out on the ice, giving birth and nursing their pups in lairs just beneath a layer of snow.6 Consequently female polar bears emerge from their maternity dens at just the right time to binge on fat, helpless ringed seal pups.7Researchers reported that one 17-year-old female with three cubs-of-the-year was handled in November 1983 when she weighed just 218 lbs. The following July, she was without cubs, probably pregnant, and weighed 903 lbs, a four-fold weight change in just eight months.8 However her gain may have been even greater, as she likely continued to lose weight from November until March or April when the first seal pups appeared.

After the surviving seal pups are weaned, adult ringed seals seek out ice edges and floes where they can lay in the sun and molt their skin during two weeks of peak sunlight in June. Although not as vulnerable as baby seals, molting seals spend 60% of their time on the ice. Once their molt is complete, ringed seals are swimming in distant open waters from July through October, far from the jaws of most hungry bears. But with the passing of September’s equinox, the sun begins to fade and adult seals return to the coast to stake out their winter territories. And savvy polar bears line the coast in anticipation.

The seals must arrive before the new ice thickens in order to develop a series of breathing holes. When the ice first forms, the seals use their heads to punch open holes in the thin ice. Then as the fast-ice thickens, they must constantly chew and claw at the ice to maintain their breathing holes throughout the winter.

Because seals require thinner ice to create their breathing holes,9 areas dominated by thick multiyear ice always sustain far fewer seals and far fewer bears.14,15 In regions like the northern Canadian Archipelago, winds pile ice against the shoreline. The winds crumple the ice and heave layers of thin ice into piles of thick rubble. The ice rubble resists melting and sets the stage for thicker multiyear ice to increase in the following years. Climate scientists have detected various cycles that alternately drive thick ice out of the Arctic or confine and compress the ice.10 These cycles range from 6 to 20 years and are associated with the North Atlantic Oscillation/Arctic Oscillation.

Since the mid 1990’s, Arctic sea ice has been behaving more like Antarctic sea ice and that has been good news for plankton, cod, seals, and bears. When the Arctic Oscillation swung to a positive phase, thicker multiyear ice was blown out from the Arctic into the north Atlantic.10 As a result the thinner replacement ice now melts more rapidly each summer, and biologically that is highly beneficial. (In the Antarctic, ice is not constrained by continents, and thick multiyear ice is relatively scarce, Although Antarctic sea ice expands much more than Arctic ice, it also melts more rapidly each summer. Still the Antarctic winter sea ice has expanded to its greatest limits during the most recent decades.).

The Deception

In 2012, polar bear experts Ian Stirling and Andrew Derocher (who predicts by the middle of this century, two-thirds of the polar bears will be gone due to rising CO2) published “Effects of climate warming on polar bears: a review of the evidence.”16 To illustrate the importance of ringed seal pups they wrote, “In the mid-1970s and again in the mid-1980s, ringed seal pup productivity plummeted by 80% or more for 2–3 years…. A comparison of the age-specific weights of both male and female polar bears from 1971 to 1973 (productive seal years), to those from 1974 to 1975 (years of seal reproductive failure), demonstrated a significant decline in the latter period.” 16

Without argument, bears always benefit from more seal pups, but Derocher’s retelling of the seals’ decline in a section titled, “Why progressively earlier breakup of the sea ice negatively affects persistence of polar bear subpopulations” was (to be kind) highly deceptive! The seals’ productivity had plummeted because the Arctic had cycled to years of heavy ice, not due to “a progressively earlier break-up. Somehow that critical point escaped peer review.

Instead of directly mentioning the heavy ice connection, they simply referenced Stirling’s 2002 paper. In that paper Stirling contradicted the “review”, “Heavy ice conditions in the mid-1970s and mid-1980s caused significant declines in productivity of ringed seals, each of which lasted about 3 years and caused similar declines in the natality of polar bears and survival of subadults, after which reproductive success and survival of both species increased again.” 7 In 2012, Stirling coauthored another paper with a seal researcher and concluded all declines were caused by heavy ice years. Their paper proposed that “the decline of ringed seal reproductive parameters and pup survival in the 1990s could have been triggered by unusually cold winters and heavy ice conditions that prevailed in Hudson Bay in the early 1990s, through nutritional stress”.7

Located south of the Arctic Circle, the Hudson Bay and Foxe Basin are naturally ice free by the end of every summer, yet these regions host robust bear populations. The lack of ice provides two benefits: it insures ample thin autumn ice required by breeding ringed seals, and it permits the summer immigration of Beluga whales, harp seals, and harbor seals into the bay. Any bear that failed to get its fill of ringed seal pups in the spring, can supplement its diet with these open-water immigrants.

Scientists can estimate a bear’s diet by taking samples of fat from the rump of a (heavily sedated) polar bear. Each prey species has a highly specific combination of essential fats. By analyzing those unique fats, they can tell what the bears have eaten. Using this method scientists have determined that ringed seals provide about 70% of the bear’s diet in the Hudson Bay. The remainder of the diet consists of resident Bearded seals, Harbor seals that typically avoid ice, and Harp seals and Beluga whales that immigrate into the bay only during the open-water season.

Elsewhere the Lancaster Sound population dines on Beluga whales nearly as much as they eat ringed seals. In the summer Belugas also herd cod into shallow embayments but get helplessly stranded when the tide goes out. Belugas are also frequently trapped by rapidly advancing winter ice. In the South Beaufort Sea, ringed seals account for 15% to 70% of the bears’ diet, while Bowhead Whales contribute from 2% to 52%, and Beluga Whales from 1% to 33%, with percentages varying widely amongst individuals.11

In the Davis Strait off the coast of Labrador, polar bears will binge on baby Harp seals that breed on the pack-ice. Harp seals are another conservation success story. Since sustainable hunting regulations were imposed, they increased from less than 2 million in the 1970s to over 5.5 million in the 1990s and the bear population grew accordingly. Contrary to popular global warming theory, Harp Seals are now spreading south. In the 1980s only 5 seals were reported on Sable Island off the coast of Nova Scotia. By 1994 the Harp Seal population had ballooned to over 1100.12

In Foxe Basin just north of the Hudson Bay, ringed seals make up about 50% of the diet. In addition to harbor seals, harp seals and bearded seals, walruses contribute 7% of the bears’ diet. Wherever walruses are abundant, they are preyed upon by bears. Along the Laptev Sea polar bears have been observed making pits behind piles of driftwood, in which they hide and wait for walruses to come ashore. On Wrangle Island the bears wait on ice-free shores, anticipating the traditional walrus haul-outs to feast on the weariest walrus that lumber ashore. Impress by their resilient hunting behavior, researchers have remarked that such varied hunting behavior explains how polar bears have thrived during the past 10,000 years when summer sea ice was much less prevalent than today.13

Literature Cited

  1. Arrigo, K. and van Dijken, G. (2004) Geophysical Research Letters, vol. 31, L08304, doi:10.1029/2003GL018978
  2. Michaud, J., t al. (1996) Feeding success and survivorship of Arctic cod larvae, Boreogadus saida, in the Northeast Water polynya (Greenland Sea). Fisheries Oceanography, vol. 5, p. 120-135.
  3. Fortier, et al. (2006) Survival of Arctic cod larvae (Boreogadus saida) in relation to sea ice and temperature in the Northeast Water Polynya (Greenland Sea). Canadian Journal of Fisheries and Aquatic Science, vol. 63, p. 1608–1616
  4. Chambellant, M. et al. (2012) Temporal variations in Hudson Bay ringed seal (Phoca hispida) life-history parameters in relation to environment. Journal of Mammalogy, vol. 93, p.267-281.
  5. Dowsley, M. and M. K. Taylor. 2006. Management consultations for the Western Hudson Bay (WH) polar bear population (01-02 December 2005). Government of Nunavut, Department of Environment, Final Wildlife Report: 3, Iqaluit, 55 pp.
  6. Kelly, B., et al. (2010) Seasonal home ranges and fidelity to breeding sites among ringed seals. Polar Biology 33:1095–1109
  7. Stirling, I. (2002)Polar Bears and Seals in the Eastern Beaufort Sea and Amundsen Gulf: A Synthesis of Population Trends and Ecological Relationships over Three Decades. Arctic, vol. 55, p. 59-76
  8. Ramsay, M, and Stirling, I. (1988) Reproductive biology and ecology of female polar bears (Ursus maritimus). Journal of Zoology (London) Series A 214:601–634.
  9. Frost, K. et al. (2004) Factors Affecting the Observed Densities of Ringed Seals, Phoca hispida, in the Alaskan Beaufort Sea, 1996–99. Arctic, vo. 57. P. 115_128.
  10. Rigor, I.G., J.M. Wallace, and R.L. Colony (2002), Response of Sea Ice to the Arctic Oscillation, J. Climate, v. 15, no. 18, pp. 2648 – 2668.
  11. Thiemann,G. et al. (2011) Individual patterns of prey selection and dietary specialization in an Arctic marine carnivore. Oikos, doi: 10.1111/j.1600-0706.2011.19277.x
  12. Lucas, Z., and Daoust, P. (2002) Large increases of harp seals (Phoca groenlandica) and hooded seals (Cystophora cristata) on Sable Island, Nova Scotia, since 1995. Polar Biology, vol 2, p. 562–568.
  13. Ovsyanikov N.G., and Menyushina I.E. (2008) Specifics of Polar Bears Surviving an Ice Free Season on Wrangel Island in 2007. Marine Mammals of the Holarctic. Odessa, pp. 407-412
  14. Stirling, I. et al. (1999) Long-term Trends in the Population Ecology of Polar Bears in Western Hudson Bay in Relation to Climatic Change. Arctic vol . 52, p. 294-306.
  15. Stirling, I. and Derocher, A. (1990) Factors Affecting the Evolution and Behavioral Ecology of the Modern. Bears: Their Biology and Management, Vol. 8, A Selection of Papers from the Eighth International Conference on Bear Research and Management, Victoria, British Columbia, Canada, February 1989 (1990), pp. 189-204.
  16. Stirling, I and Derocher, A. (2012) Effects of climate warming on polar bears: a review of the evidence. Global Change Biology (2012) 18, 2694–2706, doi: 10.1111/j.1365-2486.2012.02753.x

Adapted from the chapter The Resilient Polar Bear and 10,000 years of Climate Change in in Landscapes & Cycles: An Environmentalist’s Journey to Climate Skepticism

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84 thoughts on “Why Less Summer Ice Increases Bear Populations

  1. It just makes sense… if the bears are thriving and exist in record numbers, then their prey has to be thriving, too.

  2. More ignorane. How can you say the bears are going to go extinct when not only have their numbers increased to the point that they are a dangerous pest in many Inuit communities – and their food supply has kept pace. more than kept pace.

    Just more of the same CRL delusional political hackwork – no science there.

  3. But, but , but, scientists know more than the Inuit, right, and scientific models are always right, right?

  4. “Andrew Derocher”. Like saying “Andrew Weaver”. As a Canadian, I cringe every time I hear their names. Very intelligent, committed men, with an agenda. I am sure they do very good work, but their political bias causes their work to go in specific directions. No disrespect meant, I just have a hard time reading/listening to what they say.

  5. All makes sense. And if you include the fact that polar bears travel long distances one can reasonably assume that at least some bears follow the prey from eg Hudson Bay to Foxe Basin. Somehow the impression is still left that the hunting territory is somewhat “fixed” to a relative small area, or worse, limited by available landmasses. It would be interesting to see some figures on how and where the “fat” samples were taken. I am fairly sure there are not too many Beluga wales around Churchill.

  6. What? Warmer temperatures mean higher bioproductivity? That’s like saying there are more species in the Amazon rainforest than in the Alps.

  7. So are you saying that if the arctic polar ice minimum increases, polar bear numbers will decline? What are you saying? How can your proposed relationship of increased polar bears to decreased arctic polar ice be falsified?

  8. Looks like polar bears are opportunists. It seem logical that they would hunt what ever prey was most convenient at the time.

  9. Stands to reason that arctic bears do well or better during a climate of less arctic ice and if bears are doing well it stands to reason that is because the remainder of the animals in their food-chain are doing well in a climate of less ice.

    Some time back, once arctic bears had been counted and their population was higher than supposed, I figured it must be because their prey, their prey’s prey, et al down the food-chain was also doing fine population-wise. Just figuring though, as I am not an ecologist, biologist or specialist in the area of arctic wildlife.

    Another good idea, IMO, would be to ask the locals. I would bet they know all about bear population since they live with them – season in and out.

    A good book that discusses local indigenous people’s understanding of wildlife, amongst other things, is: “Vanishing Voices – the Extinction of the World’s Languages”, by Daniel Nettle and Suzanne Romaine.

  10. Walrus, Beluga Whales, Bowhead Whales and numerous seal species, the smallest weighing in at over 100 pounds! What a magnificent and fearsome predator. It would seem that they are exceptionally intelligence, adaptable and clever hunters also. If I were on the present Arctic rowing expedition, I would toss away my rubber bullets and load up with the nitro express loads.

  11. Jim needs to be careful. This is close to sacrelege and at SF state. Could be one more added to the Oblarny unemployment list.

  12. Yes, definitely worth the read. Dr. Ball kicks the eco-imperialists who think polar bears belong to them squarely in the pancreas.

  13. The intruding warm and nutrient-rich currents also cause less ice, which promotes more photosynthesis. Between 2003 and 2007, productivity in the Arctic Ocean increased by 23% relative to the 1998-2002 average. When phytoplankton increase, zooplankton flourish, treating whales, sea birds and young Arctic cod to a bountiful feast.2 In addition to more food, the warmer surface temperatures stimulate the “cold-blooded” Arctic cod grow faster and bigger,….

    By sheer coincidence I was looking over an abstract on something very similar.

    The regime shift of the 1920s and 1930s in the North Atlantic
    Abstract
    During the 1920s and 1930s, there was a dramatic warming of the northern North Atlantic Ocean. Warmer-than-normal sea temperatures, reduced sea ice conditions and enhanced Atlantic inflow in northern regions continued through to the 1950s and 1960s, with the timing of the decline to colder temperatures varying with location. Ecosystem changes associated with the warm period included a general northward movement of fish. Boreal species of fish such as cod, haddock and herring expanded farther north while colder-water species such as capelin and polar cod retreated northward. The maximum recorded movement involved cod, which spread approximately 1200 km northward along West Greenland. Migration patterns of “warmer water” species also changed with earlier arrivals and later departures. New spawning sites were observed farther north for several species or stocks while for others the relative contribution from northern spawning sites increased. Some southern species of fish that were unknown in northern areas prior to the warming event became occasional, and in some cases, frequent visitors. Higher recruitment and growth led to increased biomass of important commercial species such as cod and herring in many regions of the northern North Atlantic.

    http://dx.doi.org/10.1016/j.pocean.2006.02.011

    “…polar bear food chain (arctic cod−ringed seal−polar bear)…”

    http://pubs.acs.org/doi/abs/10.1021/es990740b

    No wonder polar bear numbers have been booming. No wonder they survived an ice free Arctic Ocean Ocean during the Holocene Climate Optimum. I hear a jawbone was even found dating to the Eemian interglacial. Maybe they had not become the Arctic specialists they are today.

  14. researchers have remarked that such varied hunting behavior explains how polar bears have thrived during the past 10,000 years when summer sea ice was much less prevalent than today.13

    Polar bears don’t only eat seals and beluga whales. They will also snack on fruits, veg and fish.

    Abstract
    Estimating the Energetic Contribution of Polar Bear (Ursus maritimus) Summer Diets to the Total Energy Budget

    The analysis indicated that it is possible for polar bears to maintain their body mass while on shore by feeding on arctic charr and seal blubber. Polar bears of body masses up to 280 kg could gain sufficient energy from blueberries to match the daily energy loss.

    http://dx.doi.org/10.1644/08-MAMM-A-103R2.1

    Abstract
    Food habits of polar bears on land during the ice-free period in western Hudson Bay were examined between 1986 and 1992. In contrast to previous studies, feeding on vegetation during the ice-free period was common……
    jstor.org/discover/10.2307/40511413?uid=2&uid=4&sid=21102021025777

    Abstract
    Analyses were made of 233 scats collected from islands in James Bay and 212 scats gathered on the southwest coast of Hudson Bay. Birds, primarily Anatidae, were the most commonly used summer and autumn food of bears in James Bay. Marine algae and grasses were the foods most often eaten by bears on the mainland….
    jstor.org/discover/10.2307/40508662?uid=2&uid=4&sid=21102021025777

    Abstract
    Bears which fed in the dump were significantly heavier than those which did not. There was no evidence that bears using the dump gained either reproductive or survival advantages….
    nrcresearchpress.com/doi/abs/10.1139/z85-340

    Abstract
    …During spring and summer, polar bears in some areas increased predation on migratory harp seals and beluga whales. In Western Hudson Bay, bearded seal consumption declined between 1995 and 2001 for both male and female bears and continued to decline among females up to the most recent sampling (2004)….Overall, our data indicate that polar bears are capable of opportunistically altering their foraging to take advantage of locally abundant prey…
    esajournals.org/doi/abs/10.1890/07-1050.1

  15. Joe Prins says:
    July 6, 2013 at 12:23 pm

    All makes sense. And if you include the fact that polar bears travel long distances one can reasonably assume that at least some bears follow the prey from eg Hudson Bay to Foxe Basin…..

    But the poor poly bears are going to drown. What about their poor, cute cubs? We must act now to save these delicate non-swimmers. Bring out the scuba gear. LOL.

    Abstract
    Consequences of long-distance swimming and travel over deep-water pack ice for a female polar bear during a year of extreme sea ice retreat

    ….Between an initial capture in late August and a recapture in late October 2008, a radio-collared adult female polar bear in the Beaufort Sea made a continuous swim of 687 km over 9 days and then intermittently swam and walked on the sea ice surface an additional 1,800 km…..The extraordinary long distance swimming ability of polar bears, which we confirm here, may help them cope with reduced Arctic sea ice……

    http://cat.inist.fr/?aModele=afficheN&cpsidt=24131717

    Abstract
    Polar bear cubs may reduce chilling from icy water by sitting on mother’s back

    We describe an observation of a polar bear cub on its mother’s back while the mother was swimming among ice floes in Svalbard, Norwegian Arctic. Similar observations are to our knowledge not earlier described in the scientific literature. We point out that this behaviour minimize exposure to cold water and hence significantly may reduce chilling of the cub….

    http://link.springer.com/article/10.1007/s00300-009-0721-3

  16. I can hear the distant sound of Warmista heads exploding now!

    (Polar bears will eat that, too.)

  17. And of course, because PB’s hunt on the edge of the ice pack, if there is less ice, they don’t have to travel as far, and the population density of seals must be greater.

    Sorta like a bogan with a MacDonald’s just down the road. !

    No wonder the PB’s are putting on weight, :-)

  18. Basically..

    A bit of Global warming ……is GOOD

    Increased CO2 level….. is GOOD

    It is a decline in temps and a decline in CO2 levels that will cause the Earth to suffer.

    And unfortunately, the former looks like it might be on its way. :-(

  19. Pregnant female polar bears go into pseudo hibernation to birth their cubs over the winter because there is so little food. With dens always on land usually dig into snow banks, a depleted mother and her cubs emerge in the spring with a variable amount of distance to travel to find food near the coastline, (where the food hangs out – not in the middle of the Arctic ocean). The colder it is – the further she has to travel or wait until shore ice begins to break up to enable hunting. That scenario appears to favor the idea that an abnormally colder conditions would have a more deleterious affect on polar bear population than abnormally warmer ones.

  20. Wow. Great article.
    Well researched – logical.
    Makes me remember why I love science.

  21. Here is a challenge for the Warmists (or sceptics). What would happen to the Arctic ringed seal populations and polar bear populations if the Arctic was ice-free every mid-September for the next hundred years? It has happened before during Holocene and the polar bears survived. So did the ringed seals.

    Ice free Arctic for a millennium or more…

    http://dx.doi.org/10.1016/j.quascirev.2010.08.016

    http://adsabs.harvard.edu/abs/2007AGUFMPP11A0203F

    http://geology.geoscienceworld.org/cgi/content/abstract/21/3/227

    PS, where are the trolls? Where is the gnashing of teeth? Where are the weak pant wetters?

  22. Curious. The graph of body condition shows decreasing condition during the earlier years when the globe was warming. Together with the text, it shows improving condition in recent years after the warming stopped. The easy interpretation is that bears do indeed do better with cooling. Could be a time lag, of course, but I would be interested in Jim Steel’s comment on that.

  23. The guest essayist Jim Steel may be in need of a hideout far from the Bay Area of San Francisco. We are about 1,000 miles away. If we can be of service, WUWT has the e-mail address.
    ~~~~~~~~~~~~~~~~~~~~~~

    Spelling of “Fransisco” at the top?!

  24. What is this? Polar bears will eat reindeer? But no, it’s seals and seals all the way down. The ice melts and the pooooooor seals are dooooooomed.

    Abstract
    “Predation of Svalbard reindeer by polar bears”
    Polar bears (Ursus maritimus) are believed to be obligate predators on marine mammals, and particularly, on two species of seals. This paper reports on observations of polar bears preying (n=7) and scavenging (n=6) on Svalbard reindeer (Rangifer tarandus platyrhyncus). Similar to their closest evolutionary ancestor, the brown bear (U. arctos), polar bears are opportunistic and will prey on ungulates. Reindeer are likely of minor importance to the foraging ecology of polar bears in Svalbard, but the observations suggest behavioural plasticity in response to a novel prey item.

    http://link.springer.com/article/10.1007/s003000000138

  25. Mike Jonas says:
    July 6, 2013 at 3:12 pm

    Curious. The graph of body condition shows decreasing condition during the earlier years when the globe was warming. Together with the text, it shows improving condition in recent years after the warming stopped. The easy interpretation is that bears do indeed do better with cooling….

    That’s right. That is why there numbers are up from 5,000 in the 1950s to over 25,000 today. See my references above and think again. Cod, ringed seals, ocean productivity. Look at the planet from the Equator to the poles. Do you see a pattern among the greening? No?

  26. Mike Jonas says:
    July 6, 2013 at 3:12 pm

    About your request:

    Jim Steel wrote about the ups and downs of the early chart and just prior to, speaking of the change in the ice conditions.

    From the post:

    “ In that paper Stirling contradicted the “review”, “Heavy ice conditions in the mid-1970s and mid-1980s caused significant declines in productivity of ringed seals, each of which lasted about 3 years and caused similar declines in the natality of polar bears and survival of subadults, after which reproductive success and survival of both species increased again.”

    ~~~
    You Mike, write “when the globe was warming” but it really hasn’t warmed much and the natural variations of winds and water currents are in evidence – or so it seems to me.

  27. I am going to bed now. This article does not make comfortable reading for Warmists at all. They want the polar bear population to decline but it’s just not happening. So they speculate about the future, yet the past slaps them about their lying mouths. Their religion would have collapsed a long time ago if it wasn’t for the brazen, bare faced lies and exaggerations.

  28. Jimbo, their religion would have collapsed a long time ago if it weren’t for the political rent-seekers who are making their lunch on AGW.

  29. First, many polar bear colonies live on rocky shores anyhow because that is where the walrus haul out. And, little known to the enviroweenies, there is the fact that polar bears do NOT need ice to hunt. They have strategies for hunting on ice and off oce, but females largely go out onto the ice to protect their cubs from predators and male polar bears—they spread out and are less at risk.

    SO, why are the envirowhiners all about polar bears going extinct? They need it so to further their political agenda and overall goal to get rid of humans or at least curtail all human activities.

  30. polarbearscience says:
    July 6, 2013 at 3:15 pm

    Thanks for this, Dr. Crockford, & for all you do.

  31. They had to know that they would be caught in their lies when the polar bear population did exactly what they knew it would under decreased multi-year ice conditions. Were they expecting to continue the lie and have the world believe that the polar bears were dwindling when there are actually record numbers of them? Maybe that was part of the disciplinary review a year of so ago of the ecologist claiming to having seen drowned polar bears. Maybe they were expecting to be able to just pull off the big lie and they found out that some people will not go along with it. So now they look like fools!

  32. I really think that we can’t have it both ways, we can’t on the one hand say that we don’t have to worry because sea ice isn’t shrinking that much. and say that shrinking ice is good for polar bears.

  33. I have known and worked with many people in the natural resources field for 50 years. These polar bear specialists are not unlike many others who dedicate their lives to studying one species. The critters become “family” and the emotional attachment can be very strong. Their entire lives revolve around the bears. Continued study, however, requires continued funding, and therein lies the rub. The polarbearscience website is excellent- and it traces some of the political side of the issue, including literally falsifying or failing to report data that showed the increasing populations during recent decades. The folks who bother me the most are the Suzuki NGOs who extorted a lot of money spreading the fear factor for polar bears. Money corrupts!

  34. Sure, Guys, it’s ALL good, the ice melting makes it all better. We’ll just focus on the immediate benefits this has here and now. Keep spewing more CO2 in the atmosphere, produces more melting…how’s the CH4 concentrations up there? Suppose that’s all good too!

  35. Tom Trevor says:
    July 6, 2013 at 8:09 pm

    I really think that we can’t have it both ways, we can’t on the one hand say that we don’t have to worry because sea ice isn’t shrinking that much. and say that shrinking ice is good for polar bears.

    The polar bear was selected because the catastrophic aspect of “global warming” supposedly matched its plight. Everybody was concerned–so much that “deniers” were threatened with their very lives.

    Well, along comes evidence that the polar bear ISN’T endangered, and at the same time global warming has stalled. The Warmistas are striking out on both counts.

    But your contention that we can’t have it both ways is interesting: First, worrying about sea ice isn’t going to change a thing, while this study indicates shrinking ice is GOOD for polar bears.

    When the ice begins to pile up several miles thick is when I’ll begin to worry about the survival of those magnificent creatures. Until then, we should enjoy having it both ways.

  36. Tom Trevor says:
    July 6, 2013 at 8:09 pm
    “I really think that we can’t have it both ways, we can’t on the one hand say that we don’t have to worry because sea ice isn’t shrinking that much. and say that shrinking ice is good for polar bears.”

    Who is the “we” you are referencing? The Warmists are the ones worried about whatever the Arctic ice does. Too little shrinking challenges their last gasp attempt to achieve ½ of an alleged CO2CAGW “success”, while too much shrinking drives them into paroxysms of “we’re all gonna die!” They’re probably not too happy about the versatility real bears exhibit in order to survive and avoid extinction, either, not to mention all that mysterious talk of “food chains”!

  37. Trevor: “…we can’t on the one hand say that we don’t have to worry because sea ice isn’t shrinking that much. and say that shrinking ice is good for polar bears.”

    Yeah JPeden, who is Trevor’s “we” and why not? Sea ice is well within natural variability and polar bears appear to fare better in warmer conditions. Polar bears do not live in the Arctic because it is cold and icy there, they live there because that is where the food is.

  38. Tom Trevor – “I really think that we can’t have it both ways, we can’t on the one hand say that we don’t have to worry because sea ice isn’t shrinking that much. and say that shrinking ice is good for polar bears.“. The warmists say that ice is shrinking AND that it’s bad for polar bears. It’s sufficient for their critics to show that either ice isn’t shrinking or shrinking ice isn’t bad for bears (or both).

    John F. Hultquist – “it really hasn’t warmed much and the natural variations of winds and water currents are in evidence…“. True. But most agree that there was some global warming from ~1970 for ~30 years (driven by we know not what), and that for the last few years the warming has stopped or reversed. The Arctic ice has followed overall, but with significant annual variation. From the article, I expected to see polar bear condition improve during the warming period, and stabilise or decline thereafter, but it went the opposite way. Hence my “Curious“.

    Jimbo – “their numbers are up from 5,000 in the 1950s to over 25,000 today“. I don’t dispute that, though it is possible that the earlier numbers were badly underestimated. Also, if there was an increase it may be attributable to less hunting rather than more food. Again, as I say to JFH above, the slopes in the given graph are curious, because they seem to be out of step with the text of the article.

  39. Suppose the Human population graph is good too. What Biologists refer to as a classic “J Curve”.

  40. “Guest essay by Jim Steel, Director Emeritus, San Fransisco State University”

    San Fransisco? Is that in Calafornia?

  41. Examining the population viability of the Polar bear
    (Ursus maritimus).
    Andrew Cook, Tyler Jordan, Stephanie Lynch, Amy Lowry, and Ellen O’Brien

    Abstract:
    The worldwide population viability of the Polar bear (Ursus maritimus) was examined, with particular emphasis on the Western Hudson Bay and Baffin Bay subpopulations. Through examination of numerous internet sources and primary journal articles, population status, threats and risk of decline were determined for these subpopulations. Between 1987 and 2004, the estimated population size of Western Hudson Bay declined from 1,194 to 935 individuals; a decline of approximately 22%. As a result of the additive affects of climate change and over
    harvesting, the Western Hudson Bay subpopulation is estimated to become reproductively unviable in approximately 16 years and extinct in approximately 60 years; 100% of PVA simulations have resulted in a continuous population decline after 10 years within Western Hudson Bay. The Population Viability Analysis (PVA), performed by Taylor et al. (2005), determined that the Baffin Bay subpopulation would be stable and perhaps increase in population numbers, however future predictions are dependant on fluctuating harvest rates. Based on this research, the future of polar bears is conservation dependent and will rely on specific management strategies for each population.
    Journal of Conservation Biology 3065, Vol. 1: 30-40 (2007)

    http://myweb.dal.ca/bworm/Cook_etal_2007.pdf

  42. Tom Trevor says:
    July 6, 2013 at 8:09 pm

    I really think that we can’t have it both ways, we can’t on the one hand say that we don’t have to worry because sea ice isn’t shrinking that much. and say that shrinking ice is good for polar bears.

    Who is “we”? 2007 and 20012 September sea ice extent were the lowest on the satellite record. I don’t deny that. Be careful about making sweeping statements and lumping everyone in one basket.

  43. I was listening to a radio program where pre-submitted questions were answered by various scientists specialized in the field.

    One question was “Why can’t we move the polar bears to Antarctica to ensure their survival”.

    Various problems were cited including logistics, ethics of introducing a new species to a new environment, impact on penguins, how many bears etc. But the main issue seemed to be that it might be too cold for them there.

  44. Jeremy Giels says:
    July 6, 2013 at 9:24 pm

    Sure, Guys, it’s ALL good, the ice melting makes it all better. We’ll just focus on the immediate benefits this has here and now. Keep spewing more CO2 in the atmosphere, produces more melting…how’s the CH4 concentrations up there? Suppose that’s all good too!

    We just report the facts. The point of the article is that it flies in the face of the myths spread about endangered polar bears. It says that declining sea ice has not led to the decline of the overall polar bear population as feared, but maybe the opposite. Polar bears will hunt on the beach. They will outrun seals and eat most heartily.

    As for your CH4 (methane) you really do need to relax.

    “Review paper finds growth of atmospheric methane has significantly decreased, opposite of IPCC predictions”
    http://hockeyschtick.blogspot.com/2013/05/review-paper-finds-growth-of.html

    What if Arctic seas ice began to expand over the next decade? Will people like you apologise to sceptics? We have kept our cool in the face of massive hysteria. The evidence is not on your side.

  45. Mike Jonas says:
    July 6, 2013 at 11:33 pm …..

    Since 1979 sea ice extent in the Arctic has declined. There is no evidence for a decline in their numbers since 1979. The idea that declining sea ice will dent their numbers has been shown to be false. THAT is my take home message from the article. Funny how you have a problem seeing this little fact.

  46. Did you reference the 2nd 2012 Stirling paper? If not, will you add it? Ref. 7 is to the 2002 paper. Thanks.

  47. De Ja Vu?

    Abstract
    The Early Twentieth-Century Warming in the Arctic—A Possible Mechanism

    The huge warming of the Arctic that started in the early 1920s and lasted for almost two decades is one of the most spectacular climate events of the twentieth century. During the peak period 1930–40, the annually averaged temperature anomaly for the area 60°–90°N amounted to some 1.7°C……

    http://dx.doi.org/10.1175/1520-0442(2004)017%3C4045:TETWIT%3E2.0.CO;2

    Here is another paper: Warning – model induced warming. :)

    Michael E. Mann et. al.
    Abstract
    The 15th century Arctic warming in coupled model simulations with data assimilation

    Though the most recent decades are likely to be the warmest of the past millennium, we find evidence for substantial past warming episodes in the Arctic. In particular, our model reconstructions show a prominent warm event during the period 1470-1520. This warm period is likely related to the internal variability of the climate system, that is the variability present in the absence of any change in external forcing.

    http://adsabs.harvard.edu/abs/2009CliPa…5..389C

  48. @Mike Jonas: Together with the text, it shows improving condition in recent years after the warming stopped. The easy interpretation is that bears do indeed do better with cooling. Could be a time lag, of course, but I would be interested in Jim Steel’s comment on that.

    One of the problems in interpreting wildlife trends and CO2 is using the global average instead of local temperatures. Although it may be wise to think globally, wildlife always reacts locally. Always. For example, although El Nino event cause the global average to jump, El Nino events cause heavier ice in Baffin Bay and Hudson Bay. From Mysak’s paper “We have shown that during the three simultaneous NAO and ENSO events of 1972/73, 1982/83 and 1991/92, there were larger-than-normal sea-ice extents in Hudson Bay (for 1972/73 and 1982/83) and in the Baffin Bay-Labrador Ssa region. During these three events, cold SAT anomalies produced by atmospheric circulation changes (e.g., a deepened Icelandic Low) lasted for several seasons and appeared to be an important contributing mechanism for the ice anomalies”

    Mysak, L. et al. (1996) The Anomalous Sea-lce Extent in Hudson Bay, Baffin Bay and thé Labrador Sea During Three Simultaneous NAO and ENSO Episodes. ATMOSPHERE-OCEAN 34 (2) 1996, 313-343

  49. It takes some kutzpa for a San Fran academic to write something heretical like this. He risks being strung-up.

  50. @ Bill_W Did you reference the 2nd 2012 Stirling paper?

    Here is the 2nd paper.

    Temporal variations in Hudson Bay ringed seal (Phoca hispida) life-history parameters in relation to environment Author(s) :Magaly Chambellant, Ian Stirling, William A. Gough, and Steven H. Ferguson Source: Journal of Mammalogy, 93(1):267-281. 2012.

    Conclusion in abstract: “We propose that the decline of ringed seal reproductive parameters and pup survival in the 1990s could have been triggered by unusually cold winters and heavy ice conditions that prevailed in Hudson Bay in the early 1990s, through nutritional stress and increased predation pressure. The recovery in the 2000s may have been augmented by immigration of pups, juveniles, and young adult ringed seals into the study area. We discuss the possibility of a decadal-scale biological cycle that reflects fluctuations in climatic variables, and particularly in the sea ice regime.”

  51. Polar bears are still evolving, of course, & quite rapidly, but the date of their divergence from the ancestors of brown bears (grizzlies in North America) has recently been moved back from the last glaciation to at least the previous one, but possibly much farther back in time:

    http://www.livescience.com/27910-polar-bear-divergence-brown-bear.html

    So the species has survived at least one glacial maximum (the Wisconsin glaciation’s) around 20 kya & a much warmer than present interglacial (the Eemian), ~125 kya, but probably two or more such glacial cycles. Despite their arctic maritime adaptations, they’re still bears, so can eat almost anything, animal or vegetable (maybe not wood, but definitely grass). Only the 99% herbivorous pandas have given up on omnivory.

  52. jeremy890 says:
    July 7, 2013 at 9:03 am

    Thanks! More evidence it’s ocean circulation, not CO2 in the air, that drives sea ice melt around both poles. Reminds me of the naval rule that it’s a lot easier to sink a ship by letting in water from below (torpedo) than air from the top (missile or gunfire, unless you hit a magazine).

  53. This would appear to be a great subject for the The 2013 Matt Ridley Prize. How learned papers on the subject have distorted the facts, and how polar bear populations are responding opposite to what climate scientists and the IPCC predicted.

    Once again we find that warmth is good, even for cold adapted animals. What scientists have ignored is that polar bears do not feed “on the ice”. There is no food on the ice. Food for polar bears is found at the BOUNDARY between ice and water, which relies on both melting and freezing.

    Freezing temperatures are guaranteed by the perpetual winter night above the arctic circle. However, without the melt in summer there is less photosynthesis and less opportunity for both prey and predator, which will reduce the population of both. Opposite to what was predicted by climate scientists and the IPCC.

  54. ” Only the 99% herbivorous pandas have given up on omnivory.”
    Pandas are not bears. Their closet relatives are raccoons and opposums. Just a nit-pick.

  55. Justthinkin says:
    July 7, 2013 at 11:27 am: re pandas are not bears; wikipedia (ymmv) states that the Greater Panda IS a bear.

    Polar bears are very dangerous creatures. They will stalk and kill human beings. Back in the ’80s a Chevron seismic team lost a crewman to a polar bear. Other members of the party actually witnessed the stalk and kill, but were unable to communicate with the man to save him.

    Dr. Steel: Thank you for a great article. It simply makes sense that the more “edges” there are, the more places seals can come ashore or onto the ice, and thus feed the polar bears. In deer country, the deer aren’t numerous in the high forest; hunt them around the forest edges and out in the fields, where there is so much more food to be had.

  56. I doubt very much the ice is going to disappear, but if it should, I’m sure the ringed seal would adapt to giving birth on land, and the polar bear would be able to adapt to hunting on the same. *SMH*

  57. @Samuelpepys says: Badly written and bad science. To be kind this is utter rubbish.

    Not looking for kindness, but evidence to support your claim. Evidence and citations to support your “critique” would be more useful to those who wish to understand the science behind your disagreement.

  58. This analysis, trenchant though it is, will amount to nothing — in the world where disaster soon awaits us — unless it is published. So please publish!

  59. Samuelpepys says:
    July 7, 2013 at 4:03 pm

    Badly written and bad science. To be kind this is utter rubbish.

    I notice your lack of scientific evidence to back your claim. You write 12 words and hope that people take you seriously. Your weak reaction clearly shows your cultist beliefs have been dealt a shattering blow. Go get psychological consultation. :-(

  60. John says:
    July 7, 2013 at 6:05 pm

    This analysis, trenchant though it is, will amount to nothing — in the world where disaster soon awaits us — unless it is published. So please publish!

    It has been published. Here. You know your stuff so show why it should be rejected and I’m sure Anthony will remove it. Oh, and also check out all comments and show why ALL should be rejected as back up. PS I notice your lack of evidence – what is the problem? You need help.

  61. Wow, you mean predator populations rise and fall in conjunction with the populations of their prey species? Who da thunk it.

  62. I believe that of supposedly 19 polar bear populations, only the one
    in Hudson Bay had been shown to be declining. All others were
    increasing. I think a global hunting ban that went into effect in 1973
    might have something to do with that. The bears are doing just fine,
    it seems, in contradiction to the hysterical shrieks of the warmists.

  63. @Chris R. only the one in Hudson Bay had been shown to be declining.

    They thought it was declining but it has rebounded also.

    Atkinson, S. (2012) Western Hudson Bay Polar Bear Aerial, 2011. Government of Nunavut, Department of the Interior.

  64. To Jim Steele:

    The Hudson Bay polar bear population has rebounded as well?
    Splendid! I admire and respect the big bears. They are truly
    beautiful examples of nature’s ability to produce wonderfully
    adapted creatures. I also would not want to face one without
    something like a .405 Winchester ready to hand!

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