Is it a coincidence that a paper reporting the results of a no-news study on polar bears, but which predicts future starvation due to climate change, was published two weeks to the day ahead of a climate change marketing event made up by the activist organization Polar Bears International? I doubt it.
And do I think the high-profile journal Nature Communications would not only agree to publish such a useless bit of propaganda but also rig the timing to advance the climate change emergency narrative? Silly question. And the media worldwide are of course lapping it up, happy for an excuse to promote the perils of climate change, see here, here, and here using images of fat polar bears. Image above is from the BBC headline, 13 February 2024.
They believe this strategy is effective because they think the public is stupid, but they are deluding themselves. Most people are now laughing at their obvious acts of desperation.
Polar bears are highly specialize for consuming large amounts of fat that they get from Arctic seals, whales, and walrus. Only a few vocal researchers outside main-stream polar bear science insist that polar bears could ever survive year-round by eating terrestrial foods (e.g., Ilses et al. 2013; Iverson et al. 2014; Gormezano and Rockwell 2013a,b; Prop et al. 2015; Rogers et al. 2015; Tartu et al. 2016).
I agree with leading polar bear specialists that, based on polar bear biology, only a few individual bears derive any survival benefit from foods they find or catch on land, like birds, eggs, and reindeer — with the exception of beached carcasses of whales, walrus and seals that still have fat on them (Crockford 2022; Rode et al. 2015). I’ve said this a number of times on this blog, and in my Polar Bear Evolution book (Crockford 2023) and the Polar Bear Catastrophe That Never Happened (Crockford 2019).
As I’ve said before:
Whatever food polar bears consume in the summer – whether they are on land or on the ice – doesn’t really matter. What matters is how many fat-rich seals they can consume between March and June each year. The fat put on in late winter/spring from gorging on baby seals carries polar bears over the summer, no matter where they spend it. … Well-fed bears throughout the Arctic have enough fat to see them through a 4-5 month fast and even the worst-case scenario models devised suggest that most bears in productive regions like Hudson Bay [and probably, Southern Davis Strait] would survive a 6 month fast. …Chukchi Sea and Southern Davis Strait bears, for example, are doing very well – contrary to all predictions – despite marked declines in summer sea ice because they have ample food during their critical spring feeding period when sea ice is abundant.”
The study
The paper by Pagano and colleagues (2024) looked at data from 20 Western Hudson Bay polar bears over three years (August-September, 2019-2022) to see what they were eating and how much they were active during the ice-free period they spent onshore. All but one of the bears still lost about 1kg per day regardless of what they ate, except the one bear that had found a seal carcass. They authors found a wide degree of individual variation in activity and terrestrial foods consumed among the bears, as any rational person would expect.
Polar bear specialist Jon Aars is quoted as saying:
“The area of this study is one where conditions may be very difficult for bears within a short time, if sea ice continues to disappear as predicted.”
However, sea ice in WH has not changed markedly since a step-change around 1998: although there is year-to-year variation, the amount of time that polar bears must spend onshore has not changed since then (about 3 weeks longer than in the 1980s), which is certainly not what was predicted given the increase in human-generated CO2 emissions over the last two and a half decades.
They never talk about the starving bears in Western Hudson Bay in 1983, before there was a sea ice issue. The bear below was captured with three cubs in November weighing only 218 lbs; over the winter she lost her cubs but was captured in July the following year after she had gained almost 700 lbs over the spring feeding period and pregnant again (Ramsay and Stirling 1988:615). Other bears were in similarly poor condition that year and survival of cubs was low. While polar bear biologists have not been able to say why, it wasn’t lack of sea ice (Derocher and Stirling 1992; 1995).
The “science” being touted in this new paper is a waste of precious time and money: it only confirmed what was already known. It did not advance our knowledge about polar bears in any meaningful way.
The last line of the paper confirms the whole point of the publication was propaganda:
“Ultimately, our findings reinforce the risk of starvation for polar bears on land with forecasted increases in the onshore period.” [my bold]
This is a pertinent time to remind everyone that when polar bears die, they almost always die of starvation because they have no natural enemies. Starvation is a natural cause of death for polar bears and is virtually never caused by lack of sea ice.
References
Crockford, S.J. 2019. The Polar Bear Catastrophe That Never Happened. Global Warming Policy Foundation, London.
Crockford, S.J. 2022. Fallen Icon: Sir David Attenborough and the Walrus Deception. Amazon Digital Services, Victoria. [now available thru Kindle Unlimited]
Crockford, S.J. 2023. Polar Bear Evolution: A Model for How New Species Arise. Amazon Digital Services, Victoria.
Derocher, A.E. and Stirling, I. 1992. The population dynamics of polar bears in western Hudson Bay. pg. 1150-1159 in D. R. McCullough and R. H. Barrett, eds. Wildlife 2001: Populations. Elsevier Sci. Publ., London, U.K.
Abstract. Reproductive output of polar bears in western Hudson Bay declined through the 1980’s from higher levels in the 1960’s and 1970’s. Age of first reproduction increased slightly and the rate of litter production declined from 0.45 to 0.35 litters/female/year over the study, indicating that the reproductive interval had increased. Recruitment of cubs to autumn decreased from 0.71 to 0.53 cubs/female/year. Cub mortality increased from the early to late 1980’s. Litter size did not show any significant trend or significant annual variation due to an increase in loss of the whole litter. Mean body weights of females with cubs in the spring and autumn declined significantly. Weights of cubs in the spring did not decline, although weights of both female and male cubs declined over the study. The population is approximately 60% female, possibly due to the sex-biased harvest. Although estimates of population size are not available from the whole period over which we have weight and reproductive data, the changes in reproduction, weight, and cub mortality are consistent with the predictions of a densitydependent response to increasing population size. [my bold]
Derocher, A.E. and Stirling, I. 1995. Temporal variation in reproduction and body mass of polar bears in western Hudson Bay. Canadian Journal of Zoology 73:1657-1665. http://www.nrcresearchpress.com/doi/abs/10.1139/z95-197
Iles, D.T., Peterson, S.L., Gormezano, L.J., Koons, D.N. and R.F. Rockwell, R.F. 2013. Terrestrial predation by polar bears: not just a wild goose chase. Polar Biology 36:1373-1379. DOI: 10.1007/s00300-013-1341-5.
Iverson, S.A., Gilchrist, H.G., Smith, P.A., Gaston, A.J. and Forbes, M.R. 2014. Longer ice-free seasons increase the risk of nest depredation by polar bears for colonial breeding birds in the Canadian Arctic. Proceedings of the Royal Society B 281(1779):20133128 doi:10.1098/rspb.2013.3128. Open Access. http://rspb.royalsocietypublishing.org/content/281/1779/20133128.abstract
Gormezano, L.J. and Rockwell, R.F. 2013a. What to eat now? Shifts in polar bear diet during the ice-free season in western Hudson Bay. Ecology and Evolution 3: 3509-3523. DOI: 10.1002/ece3.740. Open Access, pdf here.
Gormezano, L.J. and Rockwell, R.F. 2013b. Dietary composition and spatial patterns of polar bear foraging on land in western Hudson Bay. BMC Ecology 13:51. DOI: 10.1186/1472-6785-13-51. Open Access
Pagano, A.M., Rode, K.D., Lunn, N.J. et al. 2024. Polar bear energetic and behavioral strategies on land with implications for surviving the ice-free period. Nature Communications 15:947. https://doi.org/10.1038/s41467-023-44682-1
Prop, J., Aars, J., Bardsen, B.-J. et al. 2015. Climate change and the increasing impact of polar bears on bird populations. Frontiers in Ecology and Evolution 3 (33): 1-12. https://doi.org/10.3389/fevo.2015.00033 Open access
Stempnlewicz, L., Kulaszewicz, I. and Aars, J. 2021. Yes, they can: polar bears Ursus maritimus successfully hunt Svalbard reindeer Rangifer tarandus platyrhynchus. Polar Biology 44: 2199-2206. https://doi.org/10.1007/s00300-021-02954-w Open access. Videos are here.
Ramsay, M.A. and Stirling, I. 1988. Reproductive biology and ecology of female polar bears (Ursus maritimus). Journal of Zoology London 214:601-624. http://onlinelibrary.wiley.com/doi/10.1111/j.1469-7998.1988.tb03762.x/abstract
Rode, K.D., Robbins, C.T., Nelson, L. and Amstrup, S.C. 2015. Can polar bears use terrestrial foods to offset lost ice-based hunting opportunities? Frontiers in Ecology and the Environment 13(3): 138–145, doi:10.1890/140202 http://www.esajournals.org/doi/abs/10.1890/140202 [paywalled]
Rogers, M.C., Peacock, E., Simac, K., O’Dell, M.B. and Welker, J.M. 2015. Diet of female polar bears in the southern Beaufort Sea of Alaska: evidence for an emerging alternative foraging strategy in response to environmental change. Polar Biology 38(7):1035-1047. http://link.springer.com/article/10.1007/s00300-015-1665-4 [paywalled]
Tartu, S., Bourgeon, S., Aars, J., Andersen, M., Ehrich, D., Thiemann, G.W., Welker, J.M. and Routti, H. 2016. Geographical area and life history traits influence diet in an Arctic marine predator. PLOS ONE 11(5):e0155980 doi.org/10.1371/journal.pone.0155980 Open access
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