Polar bears out on the sea ice eat few seals in summer and early fall

Even back in the 1970s, polar bears that spent the summer and early fall on the sea ice did not eat very often and some probably didn’t eat at all


This is a polar bear with an adult hooded seal, which make up an increasing share of their food. The hooded seal can weigh up to 300-400 kg, so it is a large prey for the approximately 500 kg heavy polar bear. Credit: Rune Dietz, Aarhus University

Guest essay by Dr. Susan Crockford, zoologist (blogging at www.polarbearscience.com)

We hear endlessly about the polar bears ‘forced’ to go without food for months because of receding summer sea ice — what about all the bears that stay out on the ice over the summer? Presumably, those bears keep hunting for seals – but how many do they actually catch?

As it turns out, not very many – and for some unlucky bears in late summer, probably none. While they probably eat a bit better in late fall, if they’re lucky and persistent, by the time winter comes, biologists assume most bears again eat very little. This explains why all polar bears are at their lowest weight in late winter (March), just before Arctic seal pups are born.

[Winter – January to March; Spring – April to June; Summer – July to September; Fall – October to December (e.g. Pilfold et al. 2015, in press)]

To put it another way, the reason that polar bears in some areas easily survive an onshore fast of 4 months or more over the late summer/early fall is that they would get very little to eat (if anything) even if they stayed out on the ice. It’s the fat put on in spring/early summer (from gorging on baby seals) that carries them over the summer, no matter where they spend it.

So why do some polar bear biologists and others (e.g. Stirling and Derocher 2012) keep insisting that if late summer sea ice retreats even more in the future than it has in recent years, polar bear survival will be seriously compromised because they won’t be able to eat?

For example, Morrison and Kay (2014) made the following astonishing claim last September on the Polar Bears International website, apparently approved by PBI’s ‘chief scientist’ Dr. Steve Amstrup:

“Summer is the limiting season because polar bears depend on sea ice as a platform to hunt seals. With summer and early fall sea ice losses, polar bears have less time on the ice, eat less, and become skinnier.”

Really? Take a look at the facts.



123 thoughts on “Polar bears out on the sea ice eat few seals in summer and early fall

  1. There is evidence from the Hudson Bay popularion that in poorer seal years the bears come ashore early and forage more like their grizzly cousins. Fieldwork included filming foraging and scat analysis. Three 2013 papers published by the research team. Discussed in essay Polar Bears in ebbook Blowing Smoke. The essay of course also features Dr. Crockford.

      • DMH, am trying to follow a distinction. Appreciate more feedbaxk on it. Where the book contains additional new and relevant information on a thread topic, I cite it as reference. Else, not mentioned. Here, the facts of foraging adaptation first published in 2013, summer/fall ‘walking hibernation’ rather than true winter hibernation, and that polar bears can also be viewed generically as just a grizzly subspecies capable of adopting more grizzly like foraging behavior are all relevant to her post, and the core of the essay.
        What you could not have known is that over at Dr. Crawford’s blog link where she gives the longer peer review literature background to her short post here on this new paper, I already commented to her directly just giving all three paper citations and nothing more, for her to incorporate into her thinking and expertise on polar bears. Because she did not reference them there, nor could I find them mentioned in her relevant posts subsequent to 2013. Regards.

  2. really…..if there’s no ice the bears come on shore…..but I guess we’re to believe the seals just float around until there’s ice again

  3. I wonder how warm and cuddly polar bears would seem to environmentalists if they considered their primary prey are cute and cuddly baby seals. “Does not computer. Norman, coordinate!”

    • The biggest threat to polar bear cubs is adult male polar bears , who will kill them if they see them .
      So cuddly are Polar bears

      • Is that not common to lion “cubs” as well?
        The male lion MUST “kill” EVERY living baby lion cub already born: By biology, a female lion cannot become fertile until her baby (the cub from a previous male lion) is dead.
        Thus, when a male lion kills (conquers) another male in the wilds of Africa, he immediately kills any babies from the previous lion male. All of the females(6-8 female lions per lion male) in the previous pride then become fertile (because their cub is dead); and thus the male lion mates successfully – as far as he is concerned of course.
        If you accept Darwin as a moral role model, then this is “survival of the fittest.” Kill the babies, so you can breed more of your own babies.

      • Male lions and polar bears killing the young of other males is business as usual. It has always been thus.
        I tell my son that cruelty does not exist in Nature. Only Humans can be cruel.

    • Tonyb:
      Thank you!
      P.S. Whatever possessed those guys to lasso a polar bear from a canoe?! That is just plain nuts! That bear could have reeled them in and rolled them. Heck! Just one paw on the gunwale of that canoe and they’d all be in the drink. Polar bear sez, “Arctic explorers… Yum! Tastes like chicken.”

      • “Arctic explorers… Yum! Tastes like chicken.”
        Except for global warming activists. The global warming activists taste like watermelon.

  4. Although this suggests that fall feeding during freeze-up could be important, in the absence of data we conservatively set the kill rate at 15 days of hunting per seal killed per bear. There are no data for the winter months, so an arbitrary rate of one seal kill per bear per month was assigned.”

    So basically, they were ‘making up “data” ‘ before the climate scientists were!

      • Ian
        As the article clearly stores (see my following comment to Tim), the Lancaster Sound data was unknown, so working estimates were constructed using Beaufort Sea data. Under the circumstances, the process appears reasonable and is fully disclosed.
        That’s very different than your charge of “inventing data”.
        Sometimes the problem is with the reader, not the scientist.

    • Tim:
      My read is a different: the [area] under study was the Lancaster Sound – that is the area for which there is no data.
      The article clearly states “…There are no data [in Lancaster Sound] on the rates at which polar bears kill seals in the late fall after freeze-up when young annual ice is widespread and seals become accessible again. However, from observations in the Beaufort Sea and on the western coast of Hudson Bay, where polar bears summer on the multiyear pack ice and land, respectively, the bears move onto the young annual ice to hunt as soon as possible after freeze-up and the remains of seals killed there by bears have been observed…”.
      So data from a better known study was used to create a working estimate for the missing data in the Lancaster Sound study. All this is fully disclosed – your charge that scientists are “making data” is incorrect.

      • Chip do you think it is good science to “assign” data to an area you have no data for? You can call it “fully disclosed” but it is still a wrong method as far as I am concerned. And that is the problem with what is going on with “modified” temp data as well.

      • Tim,
        I agree with Chip. At least they stated their assumptions clearly. If new data becomes available, it will be easy to update.
        The issue here is this: the biologists involved, especially Ian Stirling, are aware of that table showing little to no feeding during summer/early fall when bears are on the ice, yet they still insist that summer is a critical feeding period for bears that are out on the ice.

      • That’s called in-filling, isn’t it? In GISS temps, wouldn’t that be similar to the case of zombie stations? It also assumes the availability of seals in Lancaster Sound is the same as in Hudson Bay and Beaufort Sea.

      • Yes, Katherine, it is called infilling and other things to boot and is most objectionable. It does not meet my standards. If you have no data, you should not borrow data from somewhere else and then proceed as if you squared with sound and rigorous scientific practices.

      • asybot, Katherine, painter
        (I may be double posting this comment because I’ve hit some wrong buttons)
        No, I don’t believe “in-filling data in a formal scientific finding (peer reviewed paper) is a valid process; in fact, if not properly disclosed, I’d consider it fraud.
        That is not what Crockford did – this is a WUWT “back of the envelope” essay by a subject matter expert, questioning an assertion that “…summer is the limiting season because polar bears depend on sea ice as a platform to hunt seals…”. I believe she had a couple interesting points:
        1) There is a lot of unknown data regarding polar bear feeding;
        2) Even with reasonable “fill-in” assumptions, summer seal kill feeding being critical to bear survival does not pass the smell test;
        3) the “scientist” claiming summer kills are critical was probably aware it’s hogwash.
        Attempting to use Federal Rules of Evidence for a WUWT essay is just nuts. If you can’t tell the difference between a peer reviewed paper and a WUWT essay, arguing with me isn’t going to help you.

      • Mea culpa.
        Sorry for the double-post. I thought I’d hit the wrong button with the 1st one & re-wrote my comment; mods couldn’t catch it in time.

    • “So basically, they were ‘making up “data” ‘ before the climate scientists were!”
      Of course. Have You ever tried tracking a hungry polar bear across broken sea ice for weeks, in darkness, blizzard conditions and -40 degrees to find how many seals he catches? Some types of field-work really sucks.

      • In-filling and 1,200km smoothing are both guessing.
        I don’t know much about the study area (or care much) but the Arctic can have areas of polynyas, ridged ice, pack ice, ice-free areas, anchor ice, close pack ice, compact pack ice, consolidated pack ice etc.

  5. I am disturbed at claimed NASA data manipulation. But an American friend tells me this, which I also find disturbing: “what’supwiththat.com gets its funding from the Heartland Institute. The Heartland Institute is an American conservative and libertarian public policy …..In 2011, the Institute received $25,000 from the Charles G. Koch Foundation.” Is this true, and if so, to what extent should we adjust our acceptance of your views in the light of how you are financially supported?

    • From sackerson:

      .In 2011, the Institute received $25,000 from the Charles G. Koch Foundation.” Is this true, and if so, to what extent should we adjust our acceptance of your views in the light of how you are financially supported?

      What “Institute”? Oh, the specific job Heartland paid Watts to prepare one report on the accuracy of the US thermometers?
      Gee. Again the claim that Heartland “bought” skeptics. If $25,000.00 paid for a skeptics viewpoint – and it did not, that “story” you were fed from “a friend” is an exaggerated piece of propaganda now several years old! – let me ask you: “How many so-called “scientists” will 92 billion dollars buy?”
      Big Government spent 92 billion dollars ( 3,680,000.00 to 1.00 budget ratio, since you apparently cannot multiply) buying the ideas and promotions and the research and the journals and the budgets and the computer programs and the staffs and even more for the universities and labs and bureaucrats needed by Big Science … just specifically FOR their Big Government “scientists” – who are not all biased, are they? – reach decision designed and intended to create carbon credits for Big Finance and Big Business and for 1,300,000,000,000.00 in new tax dollars each year.
      How much Big Government can you buy for 1.3 trillion dollars and control of the world’s energy resources? How much are you paid by Big Government for your ideas and your time?

      • I am paid by neither side. And I can multiply – not that that remotely comes into it. Where on earth do you get your debating style from? The ad hominem approach may be effective for an orator, but it’s garbage as far as logical and factual debate is concerned.
        The relevance of funding here – and it’s not just the $25k from the Koch brothers, who are a study in themselves one understands – is that you need to “come to the court with clean hands”. If, as the anti-AGW party claims, the science has been skewed by financial support tantamount to bribery, then the critics need to show that their own approach is untainted by such accusations.
        Here on the Internet, it’s great that potentially we get to learn more about more things, but like cable TV we seem to be broken up into coteries of group-thinkers.
        Any recommendations as to where to turn for an expert in this field who is genuinely independent?

    • If you look at the disposition of the donation it was for studies in the medical field, not climate related. This is easily verified right at the Heartland institute website where they list their funding. This is old news and a red herring at this point. Need anyone mention all the money that the greenies get from oil companies and the supposed unbiased government?

    • sackerson
      Your question: “to what extent should we adjust our acceptance of your views in the light of how you are financially supported?”
      My answer: none.

    • Sackperson, assuming your question is in good faith, simply read Anthony’s FAQ (accessed from the ‘about’ tab above) where he covers this.

      • Hi Geoffrey: I have now read the relevant section of the FAQs (it would be easier to find if on the top bar!) and if true (I have no reeason to believe otherwise) then I apologise to Mr Watts and thank you.
        The first answer I got implied that he is paid but so what because the other side is paid more, which obviously doesn’t satisfy.
        I have indicated to my American friends that they should look at the FAQs also.
        Best wishes – “Sackerson”.

    • Gads Sackerson, It is totally irrelevant if you accept the views of anyone here. The people on this website express what ever opinions they hold, but opinions are just opinions, but facts are facts, I suggest you not be swayed by anyone’s opinion, even your friend’s. Only be swayed by facts.

    • “I am disturbed at claimed NASA data manipulation”
      IMHO, perhaps you should reserve your anxiety for proven data manipulation by any “scientist”.

    • Govt is amazing. Drug companies are no longer allowed to supply chicken salad sandwiches to our noon tumor board conferences, because the gov thinks we doctors would then buy certain expensive drugs for our patients. Meanwhile,govt officials and law makers take rides on corporate jets and take large cash donations, but insist that won’t influence them. It would hilarious if it were not so serious.
      In the case of the drug reps, they are glad to be free of the job of providing a free lunch for us. It never got them a thing. But, the big donors are showing no signs of wanting to give less to government officials and lawmakers.
      The corruption stinks, and runs throughout govt.

      • Working for a state funded University Dental School, I was required to take “Ethics Training” annually. I was allowed to accept a meal as long as the food was consumed where it was purchased. I could not accept Tickets or free merchandise. I was not to use state owned equipment or supplies for personal or political purposes and if I knew someone who violated the ethics code and didn’t turn them in, I could be prosecuted as an accessory.
        What was your experience as a government employee, if I may be so intrusive?

      • This is in Illinois, reputably the most corrupt state in the country…

      • US FDA office in Paris is nested next door to Pfizer, sharing the same wall. How convenient. French food, French wine, French Euros….which rhymes with girls.

    • “But an American friend tells me this, which I also find disturbing: “what’supwiththat.com gets its funding from the Heartland Institute.”
      That claim is posted on DeSmogBlog and is routinely repeated as gospel by some warmists. But It is footnoted by DeSmog to an article by Richard Littlemore, which in turn basis it on the phony and discredited “Heartland strategy” document, authored presumably by Gleick and/or associates.

    • ”sackerson”
      You may have missed this, but it has been well disclosed long ago. I think others here will point out the scale of the $25k in context with the obscene funding that’s pumped into the CAGW fraud.
      I’m not a big football fan, but I think this is what’s known as an ”own goal”
      Regards, Eamon.

      • OOPS, sorry, I used a trip word, so I will re-post.
        You may have missed this, but it has been well disclosed long ago. I think others here will point out the scale of the $25k in context with the obscene funding that’s pumped into CAGW .
        I’m not a big football fan, but I think this is what’s known as an ”own goal”
        It’s also a bit O/T. The discussion is about Polar bears. I don’t suppose your friend knows anything about them either
        Regards, Eamon.

    • The Koch’s are a target of the Rockefeller/Saudi cabal. Patriots and libertarian they want to see the U.S. become energy independent and the end of the Federal Reserve. They are not the enemy, [they] are the enemy of my enemy (the Rockefeller/Saudi cabal)therefore my friends.

    • You never intended a “debate”! You took your cheap, factually challenged shot and called all replies ad hom. Our host accepted some funding for setting up a server process to distribute observation data unrelated to wattsupwiththat. No opinions were bought. IF you had been reading here long, you would have known all that, as it was the subject of a couple of posts at the time it occurred. There was no hidden funding of anything. Your assertion is like saying that someone who once did research for a pharmaceutical company can’t be trusted to comment on drug testing; it’s a nonsequitor. The funding canard has always been something the AGW proponents have used as an attempt to discredit their opponents even after it has been widely reported that the “Evil Oil Companies” have positioned themselves to make even more money riding the alternate energy train and have pumped a great deal of money into the labs supporting AGW.
      By the way, the blog title is wattsupwiththat.com! The thing you typed may have been an imitator for a while, but that domain currently does not exist.

      • I think it will be more fruitful if I ask GISS to explain themselves rather than get into the nyah nyah. I actually want to know, not just wear a campaign button for either side. There may be some respectable rationale for adjusting raw data, it happens in other fields.

    • Why don’t you just evaluate the data presented here that you won’t find in NASA publications or any other left-leaning site and ignore the “views” of the writers?
      That’s what I do– I don’t accept any statements that I don’t already know to be true or can independently verify for myself. Any person capable of independent logical thought can do the same.

      • My previous comment was for sackerson, about a mile upstream in the comments, if you can find it. It’s hard to make an understandable response when the context is so far removed.

      • Fair point, Thomas. But I’m told that much here hasn’t been peer-reviewed; possibly that’s because given the politics of modern science, career scientists daren’t stick their neck out. So then the question of motivation comes in: if we can’t trust the scientific establishment because there’s too much money riding on the issue, we have to check whether the other side is paid, too – when there are two opposing paid advocates, it’s time to look for an independent adjudicator. We’re in this mess because the establishment hasn’t been fully open about its methodology, yet the critics have to be submitted to questioning, too. Perhaps the two sides should be brought into a courtroom e.g. a TTIP challenge to the Kyoto protocol?

  6. I read the attached article but could not find any mention of them eating fish. I find this strange because I saw a film on PBS recently where they were catching migrating salmon in the fall just like other bears.

  7. Susan, what the Arctic needs is more garbage dumps, right?
    How many Polar bears does the Churchill dump support in the summer?

  8. The frigid arctic air is set to blast in on Wednesday with biting winds over the northern Plains, during the day on Thursday across the Great Lakes and central Appalachians and then Thursday night and Friday in the coastal Northeast.
    The winds will make it feel even colder with AccuWeather.com RealFeel® Temperatures 15 to 30 degrees lower than the actual air temperature.

    • REAL FEEL temps. We Canadian prairie boys used to call this the “Wimp Chill Factor”. I hate it when they do this. I’m in the tropics and even here they add a couple of degrees on with the ‘feels like’ BS.

      • The local TV media save the weather for their last five minutes, because the audience is biting at the bit to see the weather. So, when the CAGW is not happening, the same media that proclaimed it to be true and perilous, will in effect be the cure to the entire lie.

    • Could the variation in the DNA record of a sample number of bears be a function of the size of the gene pool?
      I seem to remember reading that DNA analysis of humans from around the world suggested that at some point in its evolution the home sapiens species went through a “choke point ” of just a few hundred individuals.

      • The polar bear DNA gene pool is a fascinating subplot. Polar bears are NOT, by generally accepted definitions, a distinctly separate species like donkey/horse. They are more like an adapted subspecies like dogs/wolves. See comments at the beginning of this thread for supporting references.
        The population ‘restriction’ events you refer to involve interpretation of (by definition maternal only) mitochondrial DNA, and led to early misinterpretation of polar bear evolution. It is a big deal in human evolution, for example explaining the prevelance of T2 diabetes in certain human sub populations. Not polar bears. See reply comment to DMH at beginning of this thread for references.

        • polarbearscience

          Polar bears are a true and distinct species – just a bit more recent than others.

          But, I thought a distinct specie was one that could no longer breed with the original specie? (And I understand brown bear/grizzly bear + polar bear offspring can reproduce, unlike mules.)
          Is that wrong? Or just too limiting a definition in today’s biologies?

      • RACook, that is the point. There is no precise species delineation. Think about the Darwinian idea. Infertile mules are the best example. donkeys and horses are not true species. Even though they can breed, mule offspring cannot. Do I think US coyotes and wolves are separate species? Did. One hunts solitary, small game. The other hunts in packs, big game. But they interbreed to produce various subspecies of coywolves. Some can take down white tailed deer. Others cannot.
        Nature is subtle.

      • RACook,
        Yes, it is too limiting. The idea that occasional hybridization nullifies the designation of a true species used to be taught in school because it was easy and seemed reasonable, until we started to learn (via genetic studies) how many good species occasionally interbreed.
        Think about it – there are a lot of things that are different between brown bears (aka grizzlies) and polar bears: behaviour, physiology, skeletal features, life history. A few incidents of hybridization mean nothing in an evolutionary sense – evolutionary biologist Ernst Mayr repeatedly said so.
        What Rud has suggested is a common misconception. I don’t know his background but I am an evolutionary biologist and did my Ph.D. dissertation in 2004 on the speciation process in vertebrates (including genetics and physiology, and hybridization). So my information is up to date and I try to keep on top of it.
        Hybridization is a fascinating phenomenon. I think we have a lot to learn from it (did you know that even animals from different genera can hybridize – not often, but it happens!). But hybridization with a close relative does not disprove the validity of well-recognized species like polar bears and donkeys.
        The genetics of polar bear origins is complex and not yet resolved. But in my opinion, it does not call the species identity of polar bears into question.

        • Yes, but remember, I’m grinning as I write this.
          Are “YOU” going to get between a sex-starved grizzly bear and a receptive polar bear when one (or the other, or both) want to mate with the other bare bear and tell them “NO, This is not permitted by my science book on biology and you must go away and leave each other alone?”

      • RACook,
        But there is no biology “rule” that they can’t get together – that’s the point.
        It just doesn’t happen very often, because all the stars have to line up: the male has to be sexually ready (STOP grinning, bears aren’t ready to go all year long!) and so does the female (and brown bears and polar bears have only a small window of time where these overlap). Then, they have to find each other. If they do, away they go. Really won’t make a wit of difference to their evolution over the long term.

        • I am imagining a well-sated grizzly bear and very happy polar bear, snuggling quietly beneath the furs in their newly-emptied igloo, quietly smoking a biologist after creating a new bi-polar-grizzly bear for the next spring ….
          Hmmmn. Is that how panda’s got their black-and-white furs?

      • Susan,
        The polar bear rates as a subspecies. These arguments are settled by Ma Nature and polar bears mate with brown bears, producing fertile offspring. Your link above merely details _ variation_ within the species which seems to be a difficult principle for some to grasp. According to differences in DNA, skull and other skeletal morphology, etc. mankind would be divided into 4-5 or more species if classified by the lights of the splitters (adding Pygmy, Capoid, and Australoid to the other races).
        VARIATION within the species, not such a difficult principle, but it eludes some.

      • Also, Susan, the use of the catch-all term “hybridization” to describe intra-specific breeding is specious and circular. The rule that “nature decides” is a good, solid rule and should not be overruled by circular speciousness. Those who cannot grasp the principle of “variation within the species” often resort to such circular justifications.

    • Its worse. As Dr. Crockford has been pointing out for years, that group only exists to support, and gets funding only for supporting, the CAGW polar bear endangerment meme. Sterling and his students have staked their their professional careers on it since 1988. The bears were in trouble due to inexcusable sport overhunting. That stopped in 1973. Their recovery has generally been remarkable. The disconnect between polar bear reality and prediction is as great as the disconnect between GCM modeled/ observed temperatures. Two wheels coming off the CAGW bandwagon at the same time.

      • Lorne, grizzlys and browns are two different names for close subspecies variants of Ursus arctos. Those ranging into northern US mountains from Alaska are indeed more ‘grizzly’. Why, who knows. Probably diet plus some subtle speciation onset. Still Ursus arctos; nobody disagrees AFAIK. The question I raise is whether Ursus maratimus (polar bear) is in fact a distinct separate species from Ursus arctos (yet). The newest genetic and behavioral evidence says, on the way but not yet. Well, that causes a big kerfuffle that Greenpeace and many others do not want to talk about.
        Why I raised these issues here and in the book. Even polar bear speciation is not settled as has been previously asserted. Read the book essay, and check all the footnoted references. Nullius in verba.
        Browns and polars interbreed, and are behaviorally adaptive in similar ways. Not (yet) clearly distinct species. And nobody talks about these uncertainties until my essay published and this thread. Regards.

    • Lane
      Did anybody say we did, or are you simply demonstrating a firm grip on reality?
      BTW, what constitutes a “good idea..of how many polar bears” – 2 significant digits? 3 significant digits? 4? 5?

      • Chip,
        One of the CAGW scares is that we’re running out of polar bears. That must assume we have a good idea of how many polar bears there are, because if we don’t really have a good idea how many there are, or were, then we don’t know if we’re running out of them.
        The following are the 95% CI for several polar-bear sub-populations (unless I am misinterpreting the table, which is certainly a possibility):
        Baffin Bay: 690-2402
        Davis Straight: 1833-2542
        Gulf of Boothia: 870-2314
        Southern Hudson Bay: 662-1366
        Those don’t look to me like good ideas of the numbers of bears in those sub-populations.
        Aggregate for just those four sub-populations: anywhere from 4,055 to 8,624. That doesn’t look to me like a good idea of the aggregate of the number of bears in those sub-populations.
        Also, of the 19 sub-populations, PBSG indicates “Unknown” as the estimate for five, and “Data Deficient” for “Trend Relative to historic level (approx. 25-yr past)” for twelve. Again, not looking to me like good ideas of the actual numbers of polar bears, ever.

      • Lane
        I misinterpreted your original post as you assumed the Polar Bear Specialist Group claimed to have an accurate census, and you (correctly) felt otherwise. I was excessively snarky in implying it took an hour to deduce this. I suspect we feel the same regarding the current census and population mega-trends.
        I’m not a polar bear expert (retired CFO). What little I’ve read about the topic has come from (or been linked to by) WUWT. The essence is:
        1) Nobody really knows how many polar bears there are, or what the population mega-trends are (including the US Fish & Wildlife Service);
        2) Polar bears tend to live in paces not frequently visited by nose-counting scientists;
        3) Nobody really cared about a global polar bear census until fairly recently;
        4) There are now some 20 subsets of polar bears, ensuring that at any time at least one population will be in decline – and that one subset will be extrapolated as a proxy for the entire population.

  9. ‘So why do some polar bear biologists and others (e.g. Stirling and Derocher 2012) keep insisting that if late summer sea ice retreats even more in the future than it has in recent years’, grants lots in doom few in growth . Sadly its those that go grant hunting grants are the ones that are getting on in this area , for example can you see IPCC ever using research that suggest that Polar bears numbers are growing ?

  10. Even after a lot of conservation measures there are only 25,000 polar bears. (up from 5,000 thirty years go). They are nasty vicious bloodthirsty things.
    And thankfully 99.9% of the world’s population will only ever see one in a zoo. Apart from looking cute, why does anyone give a toss whether they die out or not?

    • Yup. So see essay No Bodies on the adorable Adelie penguins of Antarctica, and the American pika. Beyond essay Polar Bears. Especially see Jim Steele’s newest post on the pika kerfuffle over at his blog. Much more informative than my feeble few paragraphs. For example, Jim proves that Beevers even diddled his field research to reach his pika Great Basin extirpation conclusions!

  11. I remember after a winter of turnips, flaccid carrots and sprouting rubber potatoes, that I didn’t feel like eating any more by spring through fall. Maybe polar bears have had it up to here with these greasy little rotters by spring. sarc off.

  12. “So why do some polar bear biologists and others (e.g. Stirling and Derocher 2012) keep insisting that if late summer sea ice retreats even more in the future than it has in recent years, polar bear survival will be seriously compromised because they won’t be able to eat?”
    How about you ask them and tell us what they say?

    • Doug, I did what you suggested by email, asking them to critique the provided draft essay Polar Bears. They did not reply, any more than Marcott and Science did on A High Stick Foul, or the Seattle Times reporter on the abridged version of Shell Games concerning “Sea Change” ocean acidification, or O’Leary in Australia concerning By Land or by Sea on his bogus SLR ice shelf collapse paper. All then guest posted by Judith Curry.
      Why do you suppose the documented and archived ‘lack of response'(s) is just so? My theory is they know they cannot respond since caught out, so retreat to their pal reviewed ivory towers, thinking us unwashed heathens cannot get across their castle ‘pal review’ moat with their drawbridge up.
      Well, in the era of internet paper access and blogs like this, that reasoning is about as sound as thinking medieval fortress castles could defend against gunpowder and cannons (early artillary).

      • “Well, in the era of internet paper access and blogs like this, that reasoning is about as sound as thinking medieval fortress castles could defend against gunpowder and cannons (early artillary).”
        Much depends on how early you are talking about. Castles persisted as viable fortresses for at least 100 years into the introduction of gun powder onto the battle field.
        While smaller than catapults and trebuchets and reusable, as the latter were generally built on siege site, those earliest gun powder cannons were not especially more effective than their torsion/gravity powered predecessors.

      • MattS, you clearly have a superior knowledge of military history. I ws going by the generalities in Keegan’s A History of Warfare, the Army War College history of war course notes, and such. Recollections from long ago.

      • The very earliest bronze siege cannons still fired stone projectiles. The castle didn’t really become obsolete until the development of early explosive shells (hollow iron cannon balls filled with gun powder.).

      • Heck, the vulnerability of classic brick-and-mortar “forts” (and castles) against cannon were rejected rather “strongly” until the Federals blasted the brick-and-mortar defenses of Fort Pulaski into dust in 8 hours during the Civil War. Used a “new” invention called “rifled cannon” …
        Turns out that “mud” and sand bags and deep trenches and walls of sand were most effective against modern weapons. And why the trenches around Petersburg VA and Vicksburg MI and Savannah GA looked like WWI battlefields.
        And thus, the Brit’s needed to re-learn old lessons when they attacked the small, deeply buried German concrete bunkers on the Somme. Seems Big Government never learns.

  13. “Polar bears out on the sea ice eat few seals in summer and early fall”
    Wait, what? Are you excusing their actions because they eat less in the summer? This is terrible! They’re still murdering thousands of innocent seals. Would you be ok with murderers as long as they cut down on their murdering in the summer? No way! Polar bears have got to go. No more eating seals! I hear chicken tastes pretty good…
    The Canadian Seal Conglomerate

    • It is not easy for a bear to nab a seal when they are not pups in the birth-den. The only opportunity is when the seal hauls out to take a nap. But seals are nervous nappers and several times a minute will open their eyes to peer around. When alarmed they slip into the water (they always nap at the edge of the ice) and they are safe there.
      Concerning the stats on how often a bear takes a seal under such conditions, I am very skeptical of the reliability of such.

  14. Susan I agree 100%. Ringed seals become mostly pelagic after weaning their young and molting by mid June. Staying on the ice after that is couter productive. Trying to connect the loss of summer ice lfrom June to September is really meaningless in terms of lost bear “habitat” and I have argued this for several years as in the essay http://landscapesandcycles.net/less-arctic-ice-can-be-beneficial.html
    However less is known to promote more photosynthesis, more plankton, more fish and fatter seals, and thus happier bears.

    • The past bears this out (no pun intended).

      The regime shift of the 1920s and 1930s in the North Atlantic
      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. Benthos associated with Atlantic waters spread northward off Western Svalbard and eastward into the eastern Barents Sea. Based on increased phytoplankton and zooplankton production in several areas, it is argued that bottom-up processes were the primary cause of these changes. The warming in the 1920s and 1930s is considered to constitute the most significant regime shift experienced in the North Atlantic in the 20th century.

  15. Susan, thank you for this fine article and your very informative blog. I see on the NOAA Sea Ice Report that the drop off in the September Minimum since 1979 is significantly more than the drop off in the March Maximum of Sea Ice. Is there a working theory as to why that might be? This is the first chart I have seen comparing the trends for both Maximums and Minimums but I dont remember reading any discussion on why that might be. Are you familiar with potential causes of this divergence?
    I noted in the NOAA link, maps of the Ice Thickness which appeared to show some growth in 2014.

  16. maccassar,
    I think you are referring to the Figure 4.2 from the Arctic report card, which I included at the end of my post (footnote 3), also found here: http://www.arctic.noaa.gov/reportcard/sea_ice.html This is the first image I’ve seen where they are both shown on the same scale and it’s quite striking.
    But no, I haven’t seen any reason given for the difference in the change – not that I can recall, anyway. Perhaps someone else has?

  17. It has been my understanding from the bit of research I’ve done that summer ice is the LEAST important measure of polar bear survivability since they don’t hunt in the summer. They hunt in the spring and fall when coming out of and going into hibernation. The ice levels at those times simply have not fallen enough to make a significant difference in their hunting/feeding. Summer ice levels are a red herring when it comes to polar bear survival. It just doesn’t matter very much to them.

  18. Though these may just be snacks, it’s a reminder that polar bears don’t just eat baby seals.

    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.
    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……
    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….
    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….
    …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…
    “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
    M. G. Dyck et al – November 2007
    Observations of a wild polar bear (Ursus maritimus) successfully fishing Arctic charr (Salvelinus alpinus) and Fourhorn sculpin (Myoxocephalus quadricornis)
    ….Here, we document observations of a young male polar bear catching Arctic charr (Salvelinus alpinus) and Fourhorn sculpin (Myoxocephalus quadricornis) by diving in Creswell Bay, Nunavut. …
    Polar Biology – Volume 30, Issue 12, pp 1625-1628
    Predation of Belugas and Narwhals by Polar Bears in Nearshore Areas of the Canadian High Arctic
    Thomas G. Smith et al – 2 August 1989
    On 18 August 1988 we found four narwhals and two dead belugas stranded on a low beach at Creswell Bay, Somerset Island. All of the narwhals and two of the belugas had been attacked and partially eaten by polar bears……..The potential large summer food resource for bears represented by odontocete whales in the High Arctic Archipelago seems to be underutilized….
    Arctic – VOL. 43, NO. 2 (JUNE1990) P. 99-102
    Lech Stempniewicz et al – 28 February 2013
    Unusual hunting and feeding behaviour of polar bears on Spitsbergen
    Prolonged chasing of an adult reindeer (Rangifer tarandus) by a polar bear (Ursus maritimus) was observed both on land and in the sea, in Magdalenefjorden, northwest Spitsbergen. Polar bears were also observed catching black guillemot (Cepphus grylle) in the sea in northwest Spitsbergen and feeding on chicks in the arctic tern (Sterna paradisea) colony in Hornsund, southwest Spitsbergen. While feeding on seabird species is unsurprising,…
    Polar Record / FirstView Article pp 1-3

  19. Soon, the polar bears will be browsing for two legged dinners along the frozen Great lakes… Chicago, Green Bay,…millions of dinners.

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