Good winter conditions on the way across the North Pole except in Svalbard – Watts Up With That?
Dr. Susan Crockford
December is late autumn in the Arctic: winter conditions are increasing but not quite everywhere. Sea ice is growing rapidly over Hudson Bay and moving slowly towards the Bering Sea but the Svalbard Islands are not yet packed with ice.
Such conditions in northern Norway have existed for most of the year since 2005: the fact that Svalbard was ice-free in December is certainly not a new development (despite the abundance of ice). in 2019 and 2021 at the end of November. This means that the traditional shed areas on the eastern islands cannot again be used by pregnant female polar bears, because they must be kept in burrows at least until the end. November or so.
Some seem to think this is a disaster: that so ‘habitat loss’ is of great concern for the survival of subpopulations, if not entire species. However, similar conditions existed in 2011 and did not result in the dramatic decline in population as measured in 2015 (Aars et al. 2017) because The bears know how to answer. They have apparently moved north to spawn on sea ice or east to the Franz Josef Land archipelago in Russia (Aars 2015). These areas still fall within the subpopulation boundaries of the Barents Sea, and researchers have known for the past two decades that bears have moved within them (Andersen et al. 2012; Derocher 2005; Maurizen et al. 2002). .
Sea ice update
Note that over the past few weeks, Canadian Ice Service Ranking for most of the Hudson Bay ice only updates once a week (on Wednesdays). This seems to be a perennial problem about this time of year. It could be related to a glitch in the satellite data, although they offered no explanation for the problem.
Svalbard . ice conditions
The image below by Andersen and colleagues, including Derocher (2012) shows the small breeding grounds of King Karls Land (Kongsoya or Kong Karis Land) as it was more than a decade ago. These islands are not used for negation if the ice block does not reach them around mid to late November.
While it is certainly true that the Svalbard/Barents Sea region has lost more ice than any other subpopulation area (Regehr et al. 2016), it is also true that polar bears are not negatively affected by the change change this. Contrary to expectations, studies since then have shown that bears are thrive: This is partly because the ice around Svalbard is still present during the crucial spring mating and feeding period (Aars et al. 2017; Lippold et al. 2019).
Furthermore, the response of polar bears to this change in sea ice conditions is not unprecedented. There is evidence of similar movements of seals and polar bears out of the Beaufort Sea when spring ice conditions were particularly severe in 1974/1975, when they previous year (1973/1974).
Marine mammal biologist John Burns noted the following in 1975 (Burns et al. 1975:77 pdf below):
“In the period from June 9 to 19 [1975] Extensive aerial surveys of seal seals were carried out in the land-fast ice areas between Barter Island and Point Lay. ..The necessity of conducting these surveys was based on observations during the winter of 1974-1975, which revealed an unusually high density of annular seals in the Chukchi Sea and vice versa in the Beaufort Sea. Observations of the Beaufort Sea were obtained by [Jack] Lentfer (personal communication).
In short, polar bears have strategies for dealing with fairly drastic changes in sea ice habitats because such changes are always present in their world: most bears not only obey a rigid plan if it threatens their survival, even if some biologists think they will.
Presenter
Aars, J. 2015. Research on polar bears at the Norwegian Polar Institute. Webinar (‘webinar’), January 14. pdf here.
Aars, J., Marques, TA, Lone, K., Anderson, M., Wiig, Ø., Fløystad, IMB, Hagen, SB and Buckland, ST 2017. Number and distribution of polar bears in the western Barents Sea. Polar research 36:1. 1374125. doi:10.1080/17518369.2017.1374125
Andersen, M., Derocher, AE, Wiig, Ø. and Aars, J. 2012. Polar bears (Ursus maritimus) delivery of maternity wards in Svalbard, Norway. Polar biology 35:499-508.
Burns, JJ, Fay, FH, and Shapiro, LH 1975. Relationship of marine mammal distribution, density and activity to sea ice conditions (Quarterly report for the quarter ended September 30, 1975, projects #248 and 249). In Environmental Assessment of the Alaska Continental Shelf, Principal Investigator Report, July-September 1975, Volume 1. NOAA Environmental Research Laboratory, Boulder, Colorado. pages 77-78. Pdf here.
Derocher 2005. Population ecology of polar bears in Svalbard, Norway. Ecosystem population 47:267-275.
http://www.springerlink.com.ezproxy.library.uvic.ca/content/765147518rp35613/fulltext.pdf
Lippold, A., Bourgeon, S., Aars, J., Andersen, M., Polder, A., Lyche, JL, Bytingsvik, J., Jenssen, BM, Derocher, AE, Welker, JM and Routti, H. 2019. Transient trends of persistent organic pollutants in Barents Sea polar bears (Ursus maritimus) related to changes in eating habits and body condition. Environmental Science and Technologyyear 53(2):984-995.
Mauritzen, M., Derocher, AE, Wiig, Ø., Belikov, SE, Boltunov, AN, Hansen, E. and Garner, GW 2002. Using satellite telemetry to determine the spatial population structure of polar bears in Norway and the western Russian Arctic. Applied Ecology Magazine 39:79-90. http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2664.2002.0690.x/abstract
Regehr, EV, Laidre, KL, Akçakaya, HR, Amstrup, SC, Atwood, TC, Lunn, NJ, Obbard, M., Stern, H., Thiemann, GW, & Wiig, Ø. 2016. Polar bear conservation status (Ursus maritimus) related to the expected sea ice decline. Biology letter 12:20160556. http://rsbl.royalcietypublishing.org/content/12/12/20160556
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