Dear P Gosselin.
Thank you for your consideration. I appreciate the opportunity to be heard. Due to the numbers of polar bears on land this season, I am busy with filming and away from the internet. My reply is not as prompt as it otherwise could be.
When I read that zoos are to be considered the key to polar bears’ survival and at the same time find that there is no discussion of sanctuary, I have to seriously question the dollars, the funding and the intent behind the “zoo” message.
While polar bears that land on eastern Canadian shores are shot and killed, while the polar/grizzly hybrids are shot and killed as soon as they are discovered, while polar bears are hazed and harassed across the Alaskan coast (leading to extreme stress and mortality); in the absence of any sanctuary, alternative habitat, or effort to repopulate traditional polar bear-land habitats, I have to seriously question what kind of “conservation” is really happening. Zoos? If this is the present course and it remains unchecked, I have to think we all are in danger.
Just to be clear, my statement that polar bears can survive climate change but for man’s greed, does not translate to “… not threatened by climate change.” Certainly, if not for the decline in sea ice, polar bears would have a better future. The contraction of polar bear populations will indeed follow the loss of sea ice habitat. The survival of a great many bears will be threatened. This threat is a “clear and present danger” directly attributable to climate induced sea ice reduction.
Polar bear extinction, however, is not a climate issue but is electively driven by human, political, policy and government action. If the true nature of polar bear ecology was acknowledged and pan-arctic land sanctuaries were established, polar bears would survive climate change and continue as a viable species on Earth. As long as the current course of “drowning polar bears” and “sea ice or death” rhetoric preempts the truth, polar bears will have little to no chance for survival.
Re: Ed’s response
Nuclear Genomic Sequences Reveal that Polar Bears Are an Old and Distinct Bear Lineage , Hailer 2012 – is the most recent study of polar bear evolution. Polar bears are an older species, not of “recent origin”, and they are distinct from brown bears, not evolved from within the subset of brown bear genetics. While Hailer suggests a date range of 338,000 to 934,000 years ago for polar bear divergence, additional studies by Yu and Krause support a divergence date of 600,000 to 1.3 million years ago. The consensus resides in 600,000 to 1 million years ago.
What has confused some of the science and resulted in the “recent origin” theory, is the denial of hybrid events taking place between polar bears and brown bears. I say “some”, because not all scientists, as well myself, had discounted hybridization as the account for the “confusion”. Coyne, in “Do Polar Bears Really Exist?”, stated the brown/polar bear mtDNA profile could likely be a result of hybridization and cautioned the interpretation of mtDNA as represented in Lindqvist. The Lindqvist study of the Svalbard jaw bone fossil flat out refuted hybrid events as being relevant and incorrectly determined the answer to the mtDNA question to be resolved with polar bears to be of recent origin. Well, five recently dead grizz/polar bear hybrids of various stages, speaks to a truth that Lindqvist would now have to consider.
The ABC brown bears of Alaska have yet to be addressed directly, but I believe they too are a population descended from the hybrid crossing of polar bears and browns as was the Irish brown bear population. What we are seeing play out in real time, here in today’s Arctic, speaks to an insight into previous hybrid events and lends a credibility that far out weighs theory and speculation. It is happening now, it happened in Ireland…
From Smith – No Ice, No Choice 2012
“35,000 years ago, amidst the last great ice age, Ireland experienced a warming, an “interstadial,” that raised temperatures to within one degree of its modern day climate. Glaciers began to melt and the Irish Sea ice retreated. Polar bears came to land at 50ºN and survived a period nearly 20ºC warmer than today’s arctic. It was this warming, the Castlepook Interstadial, that forced the range of polar bears to overlap with that of Irish brown bears. Contrary to the notion that glacial periods represent a uniformly intact cryosphere, localized warming events can occur, leading to sea ice retreat, the “forced landing” of polar bears, and climate-induced species convergence. In studying the fossil record of this period, researchers in Ireland recently confirmed that a 32,000-year old brown bear fossil was discovered to actually belong to a polar/grizzly hybrid. This hybridization challenges the idea that, during a glacial period, polar bears exist exclusive of land. The extent to which polar bears have experienced forced landings, and the extent to which this reflects upon their ability to cope with change, becomes directly related to their age as a species.”
More than one million years before the Castlepook Interstadial, the Mid Pleistocene Transition occurred, (700,000 to 1.2 million years ago). This shift in glaciation periods from a 41,000 year to 100,000 year glacial-interglacial cycles, took place concurrent with the “polar bear emergence interval” of 600,000 to 1.2 million years ago. CO2 records show that from +- 620,000 to 800,000 years ago, a glacial period of extreme cold and duration occurred, far exceeding any of the glacial periods that followed in the next 600,000 years. It is the very nature of the Pleistocene cryosphere that led to the emergence of polar bears as a species.
While polar bears are here and have clearly survived, what may never be known is to what extent and frequency that “interstadials” took place within the glacial periods, similar to the Castlepook event in the British Isles. When the cyrosphere occupied much of the northern hemisphere, arctic environments and polar bears existed in temperate latitudes, as did Ireland’s. These bears and their environment were much more subject to localized and regional climate variation than an arctic confined to high latitudes as in today’s world (until now). It is exactly the occurrence of these interstadials, along with interglacial periods that have repeatedly and continuously brought the polar bear to land and in contact with the brown bear. This repeated contact and hybridization has led to the continued ability of the the two species to produce fertile offspring nearly 1 million years after divergence. (This relationship does not preclude the polar bear from retaining its’ status as a distinct species.)
Despite the course of nature, natural selection and the process of evolution, polar/grizzly hybrids have been characterized as a threat to polar biodiversity, that species are “imperiled” by interbreeding. Citing no studies, no facts, no “science” to support (an unnamed) science article, the significance of the hybrid genetic exchange between polar bears and browns seems to be less relegated to science than it is to personal opinion. (What would Darwin say?) The forced landing of polar bears may lead to population “bottlenecks”, (referred to by Hailer). But, the role polar bear/brown bear hybrids have played in the survival of polar bears as a species, and the answer to “bottlenecks” may never be known. If the prevailing attitude is to replace science with opinion, and today’s polar/grizzly hybrids remain unprotected and shot on sight, then, maybe Zoos are the answer.
Thank you again.
Arthur C. Smith III
==========================================
Arthur C. Smith III is a filmmaker who has been filming polar bears up close for 8 years. MUST SEE VIDEO HERE!
Truly the honor is mine. Thank you for this quality enlightenment. Your work is outstanding!
Thanks for explaining ancient hybridization events and the scientific controversy surrounding them, Arthur!
It reminds me of fertile hybrid horses, hybrids between our horse and the Mongolian horse-
http://en.wikipedia.org/wiki/Mongolian_horse
The interesting thing is the offspring has an uneven number of chromosomes yet is fertile and healthy. Nature doesn’t always care much for species boundaries.
Ah Blech, linked to the wrong horse, I meant Przewalski’s horse of course:
http://en.wikipedia.org/wiki/Przewalski%27s_Horse
The reason Polar/Brown bear hybrids are fertile is that they still have the same chromosome count.
As the Przewalski horse/modern horse hybrids show, that is not always a necessary precondition. I was astonished myself when I found this, but it has to be this way, otherwise no change in the number of chromosomes could ever happen, and humans have a different chromosome count than the big apes. Somewhere along the line a change happened…
Those interested in the issue of hybridization between polar bears and brown bears should read these short notes, which I filed as official comments on the journal website pages for the two recent papers on polar bear evolution, because the authors of those papers made a number of assumptions regarding hybridization (many of which could be wrong):
http://wolf-to-woof.com/2012/05/06/polar-bear-hybrids-in-the-news-again/
And Ed, I would be interested in knowing your reference to this statement, including the page and paragraph number:
“In studying the fossil record of this period, researchers in Ireland recently confirmed that a 32,000-year old brown bear fossil was discovered to actually belong to a polar/grizzly hybrid.”
Thanks,
Susan
The link to the original paper is here behind a pay wall. It is quoted widely.
http://www.cell.com/current-biology/abstract/S0960-9822(11)00645-2
The Quote above is Arthur’s.
Thanks Ed. I was confused by the quotes.
I have that paper and the supplemental information. There is no support that I can see for this statement: “In studying the fossil record of this period, researchers in Ireland recently confirmed that a 32,000-year old brown bear fossil was discovered to actually belong to a polar/grizzly hybrid.”
There is a lot of interpretation regarding the genetic data involving proposed hybridization but I don’t see any fossil specimen described as a “confirmed hybrid.” Maybe I missed it – but I don’t see it.
Now I wonder where that information comes from…if its true, I’d like to know more about it.
If Arthus sees this, perhaps he can answer?
[…] Dear P Gosselin. Thank you for your consideration. I appreciate the opportunity to be heard. Due to the numbers of polar bears on land this season, I am busy with filming and away from the internet. My reply is not as prompt … […]
Hello Susan,
I have filmed and observed polar bear/grizzly interaction and also have questions. Regarding the referenced studies, I believe that assumptions have been made and it is more likely that the Irish brown bears are the recipient of polar bear mtDNA.
I’m looking forward to reading your comments and will respond as soon as I am able to prepare.
Thank you.
Arthur
Thanks Arthur,
Have a look at this comment I posted earlier this year on the Current Biology website in response to the Edwards et al 2011 paper that proposed an Irish origin for polar bears and multiple hybridization events in their evolutionary history. What do you think?
Comment to Edwards et al. 2011
Directionality in polar bear hybridization
Hybridization between polar bears and brown bears has recently been discussed in two influential papers on the genetic evidence for polar bear evolution [1,2]: this one (Edwards et al.), which appeared last year in this journal, and another one published earlier this year in Science Magazine. Citing Kelly et al. [3] as evidence for the existence of confirmed brown bear/polar bear hybrids, the authors of these two genetic papers suggest that gene flow between polar bears and brown bears is just as likely in one direction as the other when hybridization occurs in the wild.
Both of these papers miss an important consideration. The only hybrid example mentioned by Kelly et al. [3] was the 2nd generation offspring of a brown bear male and a hybrid female shot in 2010 in the western Canadian Arctic. Analysis of nuclear and mtDNA indicated that this animal’s hybrid mother was the offspring of a male brown bear and a female polar bear. The only other hybrid documented in the wild was the offspring of a brown bear male and a female polar bear in 2006 (details on both hybrids were reported widely in newspapers around the world, with the details of the genetic testing provided in government-issued press releases and follow-up interviews. Recently, I confirmed the accuracy of these reports with the wildlife officials involved).
Therefore, only male brown bears x female polar bear crosses have been documented in the wild. The small number of verified hybridizations does not allow quantification of past introgression, but the examples from extant wild populations indicate only male brown bears are involved in inter-species matings.
Two instances of hybridization involving polar bear males and brown bear females (the cross proposed by Hailer et al. [1]) have been documented, but both involved captive animals. In the most recent case [4], mating occurred for the first time after the animals had been together for 24 years.
Brown bears mate from mid-May to July while polar bears mate April to May, leaving a brief period in late May when an early-breeding brown bear male and a late-breeding polar bear female might get together. Brown bear males also tend to emerge from their winter dens before females, increasing the chances that a brown bear male might encounter and accept a polar bear female as a mate.
In addition, although polar bears are often larger than brown bears, polar bears are less aggressive than brown bears during interactions between them [65, see pg. 16, 69]. This behavioral difference suggests another reason why only brown bears have been documented as the male partner in all inter-species mating with polar bears in the wild. It appears that for brown bears (as for wolves and domestic dogs, among many other examples), the less aggressive species is usually the derived species and also the female partner in inter-species crosses [6-9].
Taken together, this evidence suggests that hybridization between brown bears and polar bears may be largely unidirectional in the wild and predictable based on life histories, behavior and evolutionary relationship. Although hybridization with brown bears may indeed have occurred during the evolutionary history of the polar bear, the direction of introgression must be critically assessed with documented examples of inter-species matings.
References
1. Hailer et al. 2012. Science 336, 344-347.
2. Edwards et al. 2011. Curr. Biol. 21, 1251-1258.
3. Kelly et al. 2010. Nature 468, 891.
4. Walker, M. 2009. Polar bear plus grizzly equals? BBC News Online, Friday 30 October.
5. Aars et al. 2006. Proceedings of the 14th IUCN Polar Bear Specialist Group, Seattle, Washington.
6. Bradley et al. 1991. J. Hered. 82, 192-196.
7. Crockford, S.J. 2006. Rhythms of Life: Thyroid Hormone and the Origin of Species (Victoria: Trafford).
8. Kaneshiro, K. Y. 1980. Evolution 34, 437-444.
9. Roca et al. 2005. Nat. Genet. 37, 96-100
Susan J. Crockford,
University of Victoria, Canada
Cite as:
Crockford, S.J. 2012. Directionality in polar bear hybridization. Comment (May 1) to Edwards et al., 2011. Current Biology 21: 1251-1258.
[sorry if this reply comes out twice, the first did not appear to go so this is a 2nd attempt]
Susan
Obama’s “Kill Coal” CO2 limit on new power plants leads to a surge in coal exports from the US to the EU, leading to collapsing prices. CO2 reductions go up in flames.
http://www.bloomberg.com/news/2012-07-02/europe-burns-coal-fastest-since-2006-in-boost-for-u-s-energy.html
I think the “market” is the big issue in the US and the EU usage of coal versus gas. Had shale gas via fracking not happened there would be more of a story to Obama/EPA’s attack on coal. But Obama’s skyrocketing costs of energy production hasn’t happened so US citizens remain unconcerned. The coal industry takes a hit, adjusts, and continues – just as the Canadians adjust to the no-pipeline decision. Someone has said that life is what happens while you are making plans. Gotta love it!
****Good info on the Polar Bears. Thanks for the post.****
Meaning original post by Arthur Smith and comments too.
“Citing no studies, no facts, no “science” to support (an unnamed) science article, the significance of the hybrid genetic exchange between polar bears and browns seems to be less relegated to science than it is to personal opinion.” (Arthur C. Smith III)
There is a tremendious amount of this going around these days. It seems to permeiate every field of science and everything and anything that people tend to talk about of the web. Unfortunately, it is all only likely to continue and grow bigger and badder. Just look at the success the AGW Mob has had and how high the hysteria has risen among people who are educated and old enough to know better. There was an “Age of Reason” once, and it is gone with the wind; there is an “Age of Science”, and it is blowing away also. Nothing lasts forever, not even common sense. We’re taking another dive I fear, and most are too busy buying the latest wiz-bang thing to notice or care. I thought once that another World Wide Great Depression would help, indeed that it would probably be the only thing that would, but I doubt that even that would do much to “improve” our thinking and priorities. Oh well, “That’s life!”, as they say. While we pray for our cousin of the Arctic, we need to put in a little plea for our own survival too.
I don’t have access to the paper, but I assume the nuclear DNA is mixed between brown and polar bears showing that still interbreed.
Since the mtDNA acts like a marker of the female lineage, because mtDNA passes in the maternal line, some brown bears must have polar bear mtDNA or some white bears must have brown bear mtDNA. This genetic combination would indicate interbreeding in the wild, the key biological indicator of single species.
This was an elegant experiment (survey). Did the authors conclude that brown bears and polar bears are varieties of bear and not separate species?
The evidence points to a single species, but that is certainly not the politically correct conclusion.
Dear P Gosselin,
Once again, may I offer my gratitude in being afforded an opportunity to be heard.
Susan, we are on the same page.
The polar bears that I have filmed and studied in Alaska have revealed a behavioral and social ecology that has yet to be acknowledged by western science. The world’s leading polar bear expert, Nikita Ovsyanikov, is the only scientist in the field who acknowledges the social nature of polar bears, and who has spent years living among them and observing their natural behavior on Russia’s Wrangel Island. His book Polar Bears – Living with the White Bear, mirrors my film work and study here in Alaska. His method of study, like my own, relies on non-invasive observation of the animals. This method shows what helicopters and satellite collars never could:
• friendships between adult male boars;
• the gathering of many polar bears– boars, sows and cubs grouped together, resting playfully and peacefully on barrier islands;
• adult males, recognized by females from distances of nearly one mile, then the female running across the ice to join him; their affection and interaction speaking to a heretofore undocumented aspect of polar bear behavior;
• compound families– females with their cubs of the year, alongside the spring cubs’ three-year-old sibling;
• a family reunion– a sow with spring cubs, reuniting with her twin 3-4 year olds from her previous litter.
Relying on helicopter based science to the exclusion of on-the-ground observational biology, science is blind to the interaction that occurs among individuals and generations. The invasive and detached approach of “polar bear science from the air” overlooks the bears’ social nature, which negatively impacts discussions of their conservation as a species.
The public does not see the terror and flight demonstrated by polar bears in response to their pursuit by helicopters. I have documented a peacefully sleeping polar bear family, abruptly rising to their feet and fleeing in response to hearing the approach of a helicopter at least two miles away.
I have seen the forced dislocation of 32 polar bears from their preferred region of resting and lounging while awaiting the return of annual ice. Of the 38 bears present, after the helicopters finished, only six remained. 32 bears forced to flee and relocate; what behavioral trait and understanding does this reveal, unless the point is to explore a vector of forced extirpation? Well, no one really wants to admit that polar bears need land, no one is stepping forth to provide land for sanctuary or alternative habitat to vanishing sea ice, so maybe a forced extirpation is the point. Given the “Gore-O-Manic” response to climate change, who would ever know any better?
For better or for worse, for natural or man-made, the arctic ice is melting: climate shifts are part of a cycle that has happened repeatedly in the past and will continue so without regard to whether or not humans’ sensibilities are offended. Our failings of argument and denial are providing cover for the refusal and lack of accountability concerning the truth of polar bear ecology: polar bears are social animals, coming to land. Land is necessary for their survival. In our rush to cash out the Arctic, polar bears are to be written off as a casualty of climate change.
The Hybrid Issue:
The existence of polar bear society defies the myth of the polar bear as “solitary predator.” The socialization and behavior I have witnessed and filmed, what Ovsyanikov has documented, can in no way be possessed by a “young species” that has only evolved on sea ice. (I have found historic fact that polar bears have indeed exhibited preference for land and elected to remain there, thriving for centuries. They would likely still be living had they not been shot and killed.)
I am witness to the melting sea ice, polar bears coming to land and their interactions with grizzlies. I can see from my doorstep the Arctic coast, the ice, and the polar bears that cross to land. I have seen polar bear tracks in the snow at my front steps; I have been confronted with a grizzly upon opening my front door. What I am witness to has happened before. It has happened in Ireland. It has happened in the ABC Islands of Alaska. It has happened countless times throughout the polar bears’ existence, and it is again happening in Canada. But now, in service to political and development interests, history and truths are being ignored.
Polar bears, in the face of a declining sea ice platform, exhibit a strong and overriding preference (philopatry) to remain on land in proximity to their land-based denning region. I theorize that, as the sea ice retreats, they alter their patterns and remain on land as not to be swept away on retreating ice, carried so far from land that they find it impossible to return in time for denning. I have documented this behavior in historical research and see it being exhibited now, in real time. It is their history of repeated “forced landings” due to sea ice retreat that has bound numbers of polar bears to coastal and island regions of the cyrosphere. In these regions of forced and confined proximity, the evolution of polar bear society occurred.
On an island like Svalbard, or Russia’s Wrangel Island, in the face of declining summer sea ice, polar bears remain on land altogether or return to land early. In the summer of 2007, on Wrangel Island, nearly 600 polar bears came ashore and thrived for four months. The bears engaged in a land-based harvest of other marine mammals hauled out on land (i.e., walrus). The formation of winter ice allowed the bears to return to their seasonal ice platform upon which to hunt.
To be explicit and not misinterpreted, not all regions of polar bear habitation are equally suited to support their land-based existence. In the loss of sea ice and seals for food, it is likely that some polar bear populations came ashore to find it difficult, if not impossible to supplement their diet. In times of sea ice decline and absence, the contraction of polar bear numbers is probable. Alternatively, as polar bears came to shore to inhabit regions that also served as walrus haul-outs, history has shown that the bears have achieved long term viability. I theorize that this may be, in fact, one of the key mechanisms by which polar bears have survived the prolonged absence of sea ice. Identification and conservation of these and similarly suitable land regions as polar bear sanctuaries may be the only hope for their survival as a species.
In today’s lower arctic regions and during the Pleistocene, when the sea ice that surrounded places like Ireland began to retreat, polar bears also exhibited their philopatric directive: they came to land. But unlike in the high arctic, polar bears came to islands that were destined to be free of sea ice year round. These islands may have also supported a concurrent landing of other marine mammals, and/or had many more food resources to offer; some of these land regions and islands were also populated by brown bears.
I have witnessed and filmed the familiarization process that occurs between polar bears and grizzlies. It is the social nature of polar bears and their behavioral trait of “cooperative feeding” that extends the opportunity of acceptance to the persistence of the male grizzly. The male grizzly tends to be more deferential to the polar bears feeding on a carcass, gently approaching day after day until finally he is accepted by the polar bears and is allowed to eat with them, shoulder to shoulder. Familiarization, recognition, acceptance; I have to consider these observations and behaviors as prerequisites, and/or critical factors in the process of interspecific mating. While there are likely other opportunities for familiarization to occur between the grizzly and polar bear, I believe that the behavior and nature of the female grizzly precludes the hybrid pairing with a polar bear boar.
Observations at a whale carcass reveal that the female grizzly, as opposed to the males, will tolerate the presence of no other bears, polar or otherwise, except for her cubs. She is aggressive and actively pursuant of any polar bear that approaches “her” food cache. In addition to confrontations, and face-offs, I witnessed a grizzly sow that would chase off all other bears, feed on the whale carcass, then sleep on it all night, effectively denying access to all other bears until she chose to retreat at daybreak.
Given the observed behavior, it would seem highly unlikely for a grizzly sow ever to accept the much larger and more “threatening” presence of a polar bear boar. To the familiarized grizzly male, however, the deferential posture and demeanor of the polar bear female is not only likely to invite pairing, but if the female had occasion to be a member of the polar bear group at a shared feeding site, she would, no doubt, recognize him as well.
The recent hybrids in Canada all demonstrate the pairing of a male grizzly x polar bear female. In addition to the hybrids shot in 2006 and in 2010, three additional hybrids were also shot and killed in Canada in April, 2012. From the news report describing the individuals (a sow with twin cubs), the male parent was a grizzly.
The Irish brown bear study (Ancient Hybridization and an Irish Origin for the Modern Polar Bear Matriline) concludes that the modern polar bear mtDNA matriline was as a result of hybrid crossing with Irish brown bears. The study, however, differentiated polar bear from brown bear by drawing dietary assumptions based upon bone isotopic data analysis. The diet assumptions may well point to brown bears, as well as land-bound polar bears, hybrids, or the descendants of hybrid crossings. Quite possibly, the original mtDNA may have originated from polar bears to begin with.
More importantly, however, the Irish study, the Hailer study, and the recent paper, 2.8 Million Years of Arctic Climate Change from Lake El’gygytgyn, NE Russia, all share a common conclusion: polar bears have existed and survived through ice free periods: land is a requisite component of polar bear ecology.
I love the Monty Python line “…let’s not bicker and argue over who killed who…” It seems especially appropriate in context of the polar bears and hybrids. While we can debate, find fault, deny, accuse, study, publish, disagree and focus on past events, life is happening now and deserves the benefit of the doubt. Polar bears deserve the chance to survive; they deserve their land for sanctuary.
Furthermore, polar/grizzly hybrids should be protected and studied for the invaluable contribution to science that they represent. Given the energy spent on decoding the past hybrid events, where is the clamor to study the real time, living hybrids? What does their bone isotopic data show? (Oh wait, they can be observed alive and eating… oh wait, they’re shot dead… back to the bones.) What is the heritability and dominance of polar bear and grizzly behavioral traits? Do the hybrids hibernate? What is the hybrid’s demeanor? Backcrosses? How is behavior further expressed and modified? Do the backcrosses to polar bears carry any grizzly born advantage? Hunting on land perhaps?
In the face of historical study and assumptions, I find a conspicuous lack of real time hybrid study that could answer questions no fossil record could ever provide: behavior. In a culture that embraces science as the answer, where is the science? In facing the coming change in climate, understanding and honestly assessing polar bear behavior will be the key to their survival. In the observation and documentation of life, science might find answers to questions we don’t yet know to ask; we just might learn enough to do the right thing. But, that assumes that presiding authorities and the influence and source of finances wants answers, wants what is right.
I am reminded of a conversation I once had with a top US polar bear scientist. I was told that, “We [scientists] are losing [industry] funding because we are beginning to be able to answer questions that they [industry] do not want asked.”
Read the headlines below; what simpler way to not ask questions, to neither fund nor study the relationship between grizzlies, polar bears, and land.
Life is speaking to us now, in real time, begging for science that is nowhere to be found… but then, how can anyone hear anything from the noise of a helicopter?
Respectfully submitted,
Arthur C. Smith III
First polar bear to swim to Iceland in 15 years is shot dead by police in front of sightseers
Polar Bear in Iceland’s West Fjords Killed
Polar bear shot in Iceland
Polar bear killed in Arctic ‘hazing’ operation
Polar bear shot to death in Nfld. coastal
community
Polar bears threaten Newfoundland
communities (shot)
Polar bear has close encounter with
lighthouse workers (shot)
More ‘grolar’ bears spotted in N.W.T.
Mother, two cubs shot near Ulukhaktok 2012
Bear shot in N.W.T. was grizzly-polar hybrid
Could be first 2nd generation hybrid found in wild 2010
Photo in the News: Polar Bear-Grizzly Hybrid Discovered (Shot) 2006
Edwards, Ceiridwen J., Marc A. Suchard, Philippe Lemey, John J. Welch, Ian Barnes, Tara L. Fulton, Ross Barnett, Tamsin C. O’Connell, Peter Coxon, Nigel Monaghan, Cristina E. Valdiosera, Eline D. Lorenzen, Eske Willerslev, Gennady F. Baryshnikov, Andrew Rambaut, Mark G. Thomas, Daniel G. Bradley, and Beth Shapiro. “Ancient Hybridization and an Irish Origin for the Modern Polar Bear Matriline.” Current Biology 21, no. 15 (2011): 1251-258. doi:10.1016/j.cub.2011.05.058.
Hailer, Frank, Verena E. Kutschera, Bjorn M. Hallstrom, Denise Klassert, Steven R. Fain, Jennifer A. Leonard, Ulfur Arnason, and Axel Janke. “Nuclear Genomic Sequences Reveal That Polar Bears Are an Old and Distinct Bear Lineage.” Science 336, no. 6079 (2012): 344-47. doi:10.1126/science.1216424.
Melles, Martin, Julie Brigham-Grette, Pavel S. Minyuk, Norbert R. Nowaczyk, Volker Wennrich, Robert M. DeConto, Patricia M. Anderson, Andrei A. Andreev, Anthony Coletti, Timothy L. Cook, Eeva Haltia-Hovi, Maaret Kukkonen, Anatoli V. Lozhkn, Peter Rosen, Pavel Tarasov, Hendrik Vogel, and Bernd Wagner. “2.8 Million Years of Arctic Climate Change from Lake El’gygytgyn, NE Russia.” Science, 2012. doi:10.1126/science.1222135.
Arthur,
Extremely interesting!
A question. Are the Pizzly/Groler Bears shot because they are not covered by the game laws? (They are neither Grizzly or Polar bears.) Or are they shot just because they are “other”.
An observation. Your description of Polar Bear behavior when a helicopter approaches suggests that helicopter surveys will undercount population.
Ed, I don’t believe hybrids are covered by game laws, which is probably why they are usually shot on sight.
Arthur,
Thanks so much for your detailed response. I am always fascinated to hear first-hand accounts of animal behavior, as I expect is true for other readers of this blog.
It is good to hear that your experience with observing interactions between polar bears and grizzlies fits with what I have read in the scientific literature. It also fits my model (visual model, not mathematical model!) of how polar bears evolved, from either newly-evolved grizzlies or the common ancestor of both (see http://rhythmsoflife.ca).
While I realize that the most recent genetic study (the Hailer et al. 2012 one) suggests the latter (polar bears evolved from a common polar/grizzly ancestor), I contend we probably don’t yet have the definitive answer, especially since Hailer et al propose extensive hybridization between female grizzlies and male polar bears to explain their genetic results – which as you and I have both noted, goes against the behavioral evidence.
I would like to reiterate that both polar bears and grizzlies mate in the spring/early summer. However, the socializing that you describe is happening in the late summer/early fall – in other words, after the mating season. Male tundra grizzlies are known to range over enormous distances and recently, have wandered, over the spring sea ice, up onto the western Canadian Arctic islands. Therefore, it appears that recent hybridization events have occurred in polar bear territory, not grizzly territory.
In other words, modern grizzlies are going to the sea ice in the spring to mate with polar bears rather than polar bears going on land to mate with grizzlies.
I take issue with this statement: “For better or for worse, for natural or man-made, the arctic ice is melting: climate shifts are part of a cycle that has happened repeatedly in the past and will continue so without regard to whether or not humans’ sensibilities are offended. Our failings of argument and denial are providing cover for the refusal and lack of accountability concerning the truth of polar bear ecology: polar bears are social animals, coming to land. Land is necessary for their survival. In our rush to cash out the Arctic, polar bears are to be written off as a casualty of climate change.” [my emphasis]
First – I suggest this be the last time you use the word “denial” or “denier” in a discussion of this issue. I would find it supremely offensive, as I know many others do. There are many valid and rational scientific questions about many aspects of the catastrophic global warming storyline that have yet to be answered. These questions deserve to be heard in a respectful manner and addressed.
Second – You insist that “land is necessary for polar bear survival.” I can see why you might conclude that but you should recognize that it is biased by your limited experience. As valuable and interesting as your observations are, they have been restricted to bears on land (or very close to it). Despite what you have seen with your own eyes, evidence from scientific studies does not support that statement.
The Wrangell Island polar bears you mention are part of the “Chukchi/Bering Sea” subpopulation (which is shared almost equally between Russia and the US in terms of geographic territory). This subpopulation has been tentatively estimated to number about 2,000 individuals, although no survey has yet been done (Aars et al. 2006; Obbard et al. 2010 – these are the Polar Bear Specialist Group meeting reports, available here: http://pbsg.npolar.no/en/).
If we accept that number as reasonably correct (which it very well may not be), the “nearly 600 polar bears” that you say came ashore and thrived for four months on Wrangell Island eating walrus would be about 30% of the total subpopulation. Even if another 10-30% of the regional population was scattered along the Russian shoreline and northwestern tip of Alaska, that still puts a significant proportion of all bears out on the sea ice during the late summer/early fall – about 40-50% not on land (even more if the population estimate is too low). This suggests that that polar bears do not require land in summer but rather, some bears prefer it.
In fact, over most of their range, most polar bears remain on the sea ice year-round, or at most spend only short periods on land.
Working in the southern Beaufort Sea area, which includes all of the north coast of Alaska except the western tip near the Bering Strait, Schliebe et al. (2008:1005, 1st paragraph) found that between 2000 and 2005, an average of 3.7% of all polar bears of that region spent time on land between mid-September and the end of October (estimated total population at that time was 1,526 bears). That’s about 57 bears on shore out of 1526 total. Which again suggests your insistence that polar bears require land is unsupported.
So what about pregnant females that den over the winter, you might ask? It is clear that some pregnant females that spend September/October on the sea ice do indeed come to land to make their winter dens. However, “some” is not all, as you seem to suggest.
Studies indicate that aside from Hudson Bay and Svalbard (where virtually all bears do indeed appear to den on land), around 50% of bears den on the sea ice. For example, according to the study done by Fischbach and colleagues (2007) in the southern Beaufort Sea, approximately 37-60% of females den offshore, on the ice. Which means 37-60% of females are not using land.
Amstrup and Gardner (1994:8) have stated that “Contrary to previous hypotheses (Stirling and Andriashek 1992), substantial polar bear denning occurs in the Beaufort Sea region of northern Alaska and adjacent Canada. Bears that den on pack ice are subject to risks not encountered by bears that den on land. Unstable, moving ice caused early abandonment of dens and, apparently, loss of cubs. However, the persistence of pack-ice denning indicated that those risks are not overwhelming.”
It is worth noting that according to the field work conducted by Steve Ferguson and colleagues (2000) in the Canadian Arctic, polar bears utilize so-called ‘thick’ first year ice (1.2-2.0m) for over-wintering activities, including denning. Over in the Barents Sea, north of Norway, bears are also known to den on first year ice (Mauritzen et al. 2001).
[What surprises me is that despite this known use of offshore sea ice for denning by pregnant females, the report supplied in support for the listing of the polar bear as a threatened species (Bergen et al. 2007:6) modelled only future changes to terrestrial denning habitat. It did not address offshore sea ice denning habitat at all.]
I conclude that there is no evidence from modern polar studies to support your statement that “land is necessary for polar bear survival” or that “land is a requisite component of polar bear ecology.”
Moreover, I caution you against concluding, based on the papers by Edwards, Hailer and others, that “polar bears have existed and survived through ice free periods.” Ice-free for a month or so during the summer does not mean ice-free year round. There is no evidence I know of that suggests the Arctic was ice-free in winter at any time during the mid to late Pleistocene (the Melles et al. evidence is for summer conditions on land, which tells us nothing about winter sea ice).
So, as far as I can see, there is no evidence to suggest that “land is necessary for polar bear survival” nor for the idea that polar bears were required to live a terrestrial existence during interglacial periods.
best regards,
Susan Crockford, Ph.D. (Zoology)
REFERENCES CITED:
Amstrup, S.C. and Gardner, C. 1994. Polar bear maternity denning in the Beaufort Sea. The Journal of Wildlife Management 58:1-10.
Bergen, S., Durner, G. M., Douglas, D. C., and Amstrup, S. C. 2007. Predicting movements of female polar bears between summer sea ice foraging habitats and terrestrial denning habitats of Alaska in the 21st century: proposed methodology and pilot assessment. Administrative Report, U.S. Department of the Interior-U.S. Geological Survey, Reston, VA.
Ferguson, S. H., Taylor, M. K., and F. Messier 2000. Influence of sea ice dynamics on habitat selection by polar bears. Ecology 81:761-772.
Mauritzen, M., Derocher, A.E. and Wiig, Ø. 2001. Space-use strategies of female polar bears in a dynamic sea ice habitat. Canadian Journal of Zoology 79:1704-1713.
Schliebe, S., Rode, K.D., Gleason, J.S., Wilder, J., Proffitt, K., Evans, T.J., and S. Miller. 2008. Effects of sea ice extent and food availability on spatial and temporal distribution of polar bears during the fall open-water period in the southern Beaufort Sea. Polar Biology 31:999-1010.
Stirling, I. and Andriashek, D. 1992. Terrestrial maternity denning of polar bears in the eastern Beaufort Sea area. Arctic 45:363-366.
[…] polar bears was occurred in both directions during their evolutionary history. I also re-posted the comment to Edwards et al. in a blogpost by filmmaker Arthur C. Smith III at Pierre Gosselin’s blog, No Tricks Zone. […]