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New Polar Bear Counting Method Creates Confusion

The views expressed are those of the author and are not necessarily those of Scientific American.


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A few weeks ago, the director of wildlife for Nunavut, Canada, made an unexpected declaration, claiming that the number of polar bears (Ursus maritimus) in the western Hudson Bay region is increasing, even though scientists say the population is declining. Western Hudson Bay is one of 19 distinct polar bear subpopulations, and previous research has suggested that the animals in that region could die out in 25 to 30 years as climate change eliminates the sea ice that they rely on for hunting and breeding. Media outlets such as Forbes and the Web sites of various climate change skeptics quickly picked up on the announcement and published headlines such as “Polar Bears Hate Al Gore.”

Too bad they all got their facts wrong.

The misinterpretations stem from a new aerial study (pdf) of the polar bear population in western Hudson Bay, conducted under the auspices of the Nunavut Department of Environment. The survey, conducted in August 2011, estimated the total population of polar bears in the region to be 1,013 animals, derived from a statistically plausible range of between 717 and 1,430 bears. The actual number of bears observed was 701.

Before this aerial survey, the most recent estimate of polar bears in that region was 935 animals in 2004, down from 1,194 in 1987. The new number, according to the wildlife director, shows that polar bear populations are increasing.

But here’s the thing: all previous counts of the polar bear population in western Hudson Bay used a different methodology called capture–recapture, in which animals are quite literally captured, studied, marked and released. Later recaptures can then provide a statistical estimate of population size. The differing methodology between the two studies—plus the fact that the aerial surveys were conducted over a slightly different and larger geographical area than the capture–recapture studies—means that the two counts are apples and oranges: They can’t be compared against each other in the hopes of determining a trend.

And in fact, the aerial study does not compare itself against the earlier capture–recapture surveys, nor does it claim that populations are increasing. Instead, it reads, “This aerial survey-based estimate is not significantly different from the 2004 mark–recapture estimate.” It does point out that the 2004 capture–recapture study predicted the population would fall to 650 by this time, but says it is too early to make any real comparisons. Another capture–recapture survey was apparently also conducted in 2011 and estimates will be released later this year, at which time the report says the two studies can be formally compared.

The aerial survey did come up with one interesting discovery: The western Hudson Bay population has a very low level of young bears, with yearlings (young between one and two years old) representing just 3 percent of the observed animals. According to Steven Amstrup, chief scientist for Polar Bears International, the number of yearlings in a population should be closer to 15 percent. “This is classic population dynamics,” Amstrup says. “If you have declining habitat quality, the first thing you’re going to see impacted is the survival of young.” He points out adult polar bears have energy stores that the young lack, so adults are more likely to survive tough times than are their offspring.

In addition to the low number of cubs, the report says the average observed litter size was the lowest ever recorded in all three Hudson Bay polar bear subpopulations—western and southern Hudson Bay and Foxe Basin—suggesting that reproductive output in the region “was poor in 2011.”

Another interesting element about the report is its reason for existence in the first place. The aerial survey was a response to concerns from the Inuit population that they are seeing more polar bears entering their communities, giving rise to a belief that there are more bears in the region rather than fewer. The report calls this a “disparity” between science and “traditional ecological knowledge.” It says the Inuit have doubts about the accuracy of the previous capture–recapture surveys and have called for new research to reassess the population.

“Many people in the ground haven’t really believed the estimate derived by the scientists because they are seeing more bears,” Amstrup says. He also says the fact that bears appear where they did not previously roam indicates that the animals’ food system is broken. “They’re going into new territories looking for something to eat.”

The lowering of hunting quotas has also caused some ill will in the region. Last year Nunavut raised the quota in western Hudson Bay, where hunting has had both traditional and economic importance, from eight bears to 21, still well below the 56 allowed in 2006. Quotas were lowered based on the projections from the earlier population studies, so any studies that show an increasing population could be used to bring quotas back up.

Ultimately, though, Amstrup says the biggest concern is not whether polar bear populations are increasing or decreasing today, but whether or not they will be able to survive into the next century. “If we stay on the path we’re on with greenhouse gases, we’re going to lose them all,” he says.

Polar bears are listed as vulnerable to extinction by the International Union for Conservation of Nature. The species is listed as threatened under the U.S. Endangered Species Act. Canada lists it as a species of “Special Concern.” Canada is home to two thirds of the world’s polar bears.

Photo: A polar bear in Nunavut by Rich Durant, via Flickr. Used under Creative Commons license

John R. Platt About the Author: Twice a week, John Platt shines a light on endangered species from all over the globe, exploring not just why they are dying out but also what's being done to rescue them from oblivion. Follow on Twitter @johnrplatt.

The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. singing flea 1:29 pm 05/10/2012

    The Inuits will eat themselves out of the debate when the last polar bear is the special guest of the last great bearfest.

    Link to this
  2. 2. outsidethebox 3:58 pm 05/10/2012

    Or as Amstrup might put it, “It doesn’t make any difference what the facts on the ground are – it’s my theories that are important!” Yawn.

    Link to this
  3. 3. Trent1492 5:01 pm 05/10/2012

    I see that the fake skeptics continue the trend of:

    1.Not reading the article they make moron comments on.

    2. Make up quotes about people they disagree with.

    Link to this
  4. 4. geojellyroll 5:08 pm 05/10/2012

    The study was endorsed by Environment Canada.

    However, it doesn’t pass the purple Kool-ade test of the global warming groupies.

    Link to this
  5. 5. Trent1492 7:35 pm 05/10/2012

    And here comes Geo-Jelly-Brain committing error #1 with a dash of ad hominem mixed in. So predictable and moronic.

    I wonder if the fake skeptic read this portion of the article?

    “The aerial survey did come up with one interesting discovery: The western Hudson Bay population has a very low level of young bears, with yearlings (young between one and two years old) representing just 3 percent of the observed animals. According to Steven Amstrup, chief scientist for Polar Bears International, the number of yearlings in a population should be closer to 15 percent. “This is classic population dynamics,” Amstrup says. “If you have declining habitat quality, the first thing you’re going to see impacted is the survival of young.” He points out adult polar bears have energy stores that the young lack, so adults are more likely to survive tough times than are their offspring.”

    So sad that so called critical thinkers seem to do everything but think and read.

    Link to this
  6. 6. Carlyle 3:03 am 05/11/2012

    There could not possibly be any good news in the AGW camp. If there is a hint of any, suppress it, discredit it but on no account accept that things are not as bad as had previously been claimed.
    Just like they did when bear expert was refused permission to speak:
    Polar bear expert barred by global warmists
    Mitchell Taylor, who has studied the animals for 30 years, was told his views ‘are extremely unhelpful’ , reveals Christopher Booker.
    http://www.telegraph.co.uk/comment/columnists/christopherbooker/5664069/Polar-bear-expert-barred-by-global-warmists.html

    There are plenty of other links for those who chose to shoot the messanger rather than accept anything outside their little box.

    Link to this
  7. 7. Jerzy v. 3.0. 5:52 am 05/11/2012

    I for one cheer that there is more polar bears than previously thought.

    Link to this
  8. 8. geojellyroll 8:44 am 05/11/2012

    Carlyle: “There could not possibly be any good news in the AGW camp. If there is a hint of any, suppress it, discredit it but on no account accept that things are not as bad as had previously been claimed.”

    Exactly. The global warmists use the strategy of any cult….drink the purple Kool-ade or we all perish. Woe be to those who refuse to accept ‘the Truth’.

    Link to this
  9. 9. Trent1492 2:39 pm 05/11/2012

    I see that Carlyle and Geo-Jelly-Brain with the credulity of dim-witted five years olds have embraced an opinion article by a demonstrable liar.

    So why do I call a columnist a liar? Well, the best example is the article that Carlyle linked too:

    Here is where the lies lay:

    1. Mitchell Taylor is a retired and is thus no longer ELIGIBLE under the Polar Bear Specialist Group rules. That is a rule that Mitchell Taylor himself helped formulate.

    2. According to Dr. Derocher he was NEVER a student of Taylor’s.

    3. Taylor was never the supervisor of Dr. Derocher.

    You can see the exposition of this sorry house of lies here:

    Deltoid:

    Christopher Booker’s misinformation about the Polar Bear Specialist Group:

    http://scienceblogs.com/deltoid/2009/07/christopher_bookers_misinforma.php

    Excerpt from the article:
    “Dr. Taylor RETIRED* from the Nunavut government last year and was replaced on the Polar Bear Specialist Group by Dr. Lily Peacock. Further, Dr. Taylor was not re-appointed the to the PBSG by the Canadian government that decided to appoint 3 other people to the PBSG meeting here in Copenhagen. Involvement with the PBSG is RESTRICTED* to those ACTIVE* in polar bear research and management and Dr. Taylor no longer fits within our guidelines of involvement. Dr. Taylor years ago was involved in drafting the rules that govern our Group – …”

    And here is more from Dr. Derocher’s own correspondence:

    “It was an unfortunate article and it was grossly misleading. For example, *I NEVER Was a STUDENT OF Dr.TAYLOR’S… I can assure you that AT NO POINT DID HE EVER SUPERVISE ME in any capacity.”

    So the question once again arises why Carlyle and Geo-Jelly-Brain decided to give full credibility to a known liar. Shilling or stupidity?

    *Capitalization for the hard of learning.

    Link to this
  10. 10. Carlyle 5:11 pm 05/11/2012

    Another critic suppressed. Thiry years experience whitewashed. Being retired was not the reason the conference refused to allow him to speak.

    Link to this
  11. 11. Trent1492 8:40 pm 05/11/2012

    @Carlyle,

    Which part of the lies you propagated being exposed did you not understand?

    Link to this
  12. 12. Carlyle 9:27 pm 05/11/2012

    Precisely as I predicted. You attacked the messenger i.e. journalist, nothing about the credibility of Dr. Taylor who had vastly more experience than most if not all the other delegates. Are you disputing Dr Taylors credibility? If so say so.

    Link to this
  13. 13. Trent1492 2:30 pm 05/12/2012

    @Carlyle,

    It has been pointed out in detail how the columnist lied. Repeating the lie does not make it anymore true.

    And yes, I am calling Dr. Taylor a liar. That is unless you can show me that in fact:

    1. He was Derocher’s teacher

    2. Dercocher’s Supervisor.

    3. The rules as written do not actually exclude the retired.

    That you think a retired professor has precedence over active researchers only reveals your bias.

    Link to this
  14. 14. Carlyle 7:13 pm 05/12/2012

    So you are an expert this morning, retire at mid day & are a has-been this afternoon. The new researcher who started in the afternoon is nw the expert.
    Tell me. If this is not simply a method of excluding people you do not want to hear from why accept anything from retired people as being relevant. Lets exclude all researchers who are retired or dead. You claim that in fact, being retired was not against the rules. Why was he excluded then unless the organiser simply did no want his knowledge & experience being aired?
    By the way, exclude all those also who have been guilty of telling a porky, whether or not it is relevant to the discussion at hand. How many AGW delegates would that leave do you suppose?
    I do not know if he exaggerated or not re Derocher or whether the journalist exagerated.

    Link to this
  15. 15. Trent1492 8:22 pm 05/12/2012

    Carlyle,

    It is grossly obvious that you have not a clue about what you are talking about. Do you understand that we are not simply talking about a speaking engagement but an active research project?

    Do you understand that if Taylor has something substantial to say then he should be stepping out of retirement and publish his works?

    Going to a known newspaper columnist who is notorious for playing fast and loose with the facts is not how science is conducted. That you think science is settled by such means is a testament to your willful ignorance.

    If you have evidence that suppression occurred present it. You made the accusation the burden of proof is upon you.

    So let us recap the known lies:

    is unless you can show me that in fact:

    Please show the following:

    1. He was Derocher’s teacher

    2. Dercocher’s Supervisor.

    3. The rules as written do not actually exclude the retired.

    Link to this
  16. 16. Carlyle 8:59 pm 05/12/2012

    After thirty years in the field his views & observations were not worth hearing? Were the delegates who were accepted all more expert in the field?

    Link to this
  17. 17. Carlyle 3:42 am 05/13/2012

    Have a look at this, then tell me of any delegate to the conference that had anything like this record. http://scholar.google.com/scholar?hl=en&lr=&scoring=r&q=mk+Taylor+polar+bears&as_ylo=2004&btnG=Search

    Link to this
  18. 18. Trent1492 4:30 pm 05/13/2012

    @Carlyle,

    Why is it you feel exempt from providing evidence for your claims? I keep asking this question and you keep refusing to answer.

    Let us revisit those unproven claims again:

    Please show the following:

    1. He was Derocher’s teacher

    2. Dercocher’s Supervisor.

    3. The rules as written do not actually exclude the retired.

    Why do you feel so privileged that you are exempt from providing evidence?

    Carlyle Says: Were the delegates who were accepted all more expert in the field?

    Trent Says: How about you do this: Go to ALL of the present list of scientist on the research group and go look at their publication record and that would include such things as an the I.F factor of the journals.

    Then you need to tell us why a RETIRED researcher should take the place of an ACTIVE researcher? If he is not doing any research why should he be on the research group?

    Now onto your latest set of disinformation.

    Carlyle Says: Ater thirty years in the field his views & observations were not worth hearing?

    What would someone who has been RETIRED and is not doing ACTIVE research know about CURRENT population surveys? By osmosis? The spirit of the polar bear population comes down and whispers it in his ear?

    Link to this
  19. 19. Carlyle 5:19 pm 05/13/2012

    He could have told them where to look. A large population of bears that his successors claimed had disapeared before that conference later turned up in another area that they sometimes frequent.

    Link to this
  20. 20. Carlyle 5:37 pm 05/13/2012

    By the way, the local natives had told the researchers where the bears were likely to be. Perhaps they did not want them found before the conference. Just like the melting Himalayan glaciers claim was known to be false but was not disclosed until after the conference. Any pattern here?

    Link to this
  21. 21. Trent1492 2:26 pm 05/14/2012

    So let us review what Carlyle is still refusing to answer:

    et us revisit those unproven claims again:

    Please show the following:

    1. He was Derocher’s teacher

    2. Dercocher’s Supervisor.

    3. The rules as written do not actually exclude the retired.

    4. Then you need to tell us why a RETIRED researcher should take the place of an ACTIVE researcher? If he is not doing any research why should he be on the research group?

    Carlyle Says: He could have told them where to look.

    Trent Says: Oh, so you think that other Polar Bear researchers do not know where to look for Polar Bears. Got it. Tell me, does he have all the tracking collars besides his bed or something?

    A Carlye Says: A large population of bears that his successors claimed had disapeared before that conference later turned up in another area that they sometimes frequent.

    Trent Says: You just made that up. It is like you did not read the article or something.

    From the article:

    “And in fact, the aerial study does not compare itself against the earlier capture–recapture surveys, nor does it claim that populations are increasing. Instead, it reads, “This aerial survey-based estimate is not significantly different from the 2004 mark–recapture estimate.”

    Why did you choose to lie about this?

    Link to this
  22. 22. Trent1492 2:30 pm 05/14/2012

    Carlyle Says: By the way, the local natives had told the researchers where the bears were likely to be.

    Trent Says: We already demonstrated that opinion article is a load of tosh. Why do you insist other wise?

    Carlyle Says: Just like the melting Himalayan glaciers claim was known to be false but was not disclosed until after the conference. Any pattern here?

    Trent Says: Yes, I see a pattern of you repeating long debunked lies. Just like you repeated the lie about the Greenland Glaciers.

    Link to this
  23. 23. Carlyle 3:40 am 05/15/2012

    I have searched for much of the day for the link to a report I read a couple of months ago about the bear colony mentioned above. So far without success. I will post the link when I find it.

    Link to this

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