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Polar bears in Davis Strait in eastern Canada are thriving – Watts Up With That?


By Polar Bear Science

Dr. Susan Crockford

Packing ice is pouring down the Labrador coast, almost certainly carrying polar bears in Davis Strait. And according to new survey results, those bears are doing well: numbers are stable, bears are fatter than they were in 2007 and cubs are surviving – largely thanks to Abundant harp seals.

Based on summarythe 2017-2018 survey produced a population estimate of 2,015 (range, 1,603-2,588), which is statistically indistinguishable from Research 2005-2007 estimated at 2,158 (range 1,978-2,338). Note that the range of potential error is much larger than the most recent estimate, which is a result of the different methods used (Dyck et al. 2021; Peacock et al. 2013). No bears were captured and handled for the 2018 study (full report is yet to be published).

Interestingly, in 2007 the body condition of the bears was recorded as worse than it ever was in the 1990s, but the population size has increased markedly (Rode et al. 2012). Currently, the bear’s body condition has improved, but the number Not increase.

I suggest that it is very likely that the actual number of bears in the population is at least slightly larger than official estimates suggest: the true number is closer to the upper end of the estimated range than in the middle. Of course, that’s always the case since these estimates are based on counting a sample of bears and extrapolating to the entire area using a mathematical model.

However, this is why other metrics matter. Good body condition and good cub survival indicate a population is in good shape. Similar indicators were seen in Sub-populations in the Barents Sea and the Chukchi . Sea (Aars et al. 2017; Norwegian Polar Institute 2021; Rode et al. 2014, 2018).

To be sure, 2017 and 2018 featured more bear sightings along Labrador and the north coast of Newfoundland than in 2007. In contrast, sea ice spread along that coast in 2007 but no leopard. No reports of polar bear sightings.

A few seen in 2008 and a bunch of trouble in 2012 resulted in several bears being killed over safety concerns. Then in 2017 and 2018 – the same years of the most recent census – there were numerous reports of more sightings: at least nine cases in 2017 in the context of broadband and even more (12-18) in 2018 (Crockford 2020:34).

Labrador Sea Ice 2022

First big picture:

This year’s sea ice conditions show Davis Strait ice (light green) moving rapidly southwards against thinner, newly formed ice (purple) along the coast.

Compare the above with 2017, when the ice very thick at the end of the season in northern Newfoundland: thicker first-year ice from the north (light green) has replaced virtually all new ice along the coast.

Time will tell whether the ice off Newfoundland in April will be as thick as it was in 2017 but for now, conditions are excellent for East Coast seals that can give birth in March and polar bears. Davis sea will come to feed them.

Presenter

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.

Crockford, SJ 2020. The status of the Polar Bear 2019. Global Warming Policy Fund Report 39.

Dyck, M., Dunham, KD, Ware, JV, Koons, DN, Regehr, EV, Hosmer, DW, Derocher, AE, Dale, A., Pisapio, J. and Szor, G. 2021. Re-evaluating the abundance of polar bear populations in Davis Strait by genetic signature acquisition. Final report to Nunavut Wildlife Department. Government of Nunavut, Igloolik, December 17. Two pages of summary and title page provided by AE Derocher via Twitter https://twitter.com/AEDerocher/status/1473001033257218051; The full final report had not yet been published at the time this report was written.

Norwegian Polar Institute. Year 2021. Number of cubs per litter, number of females with cubs of different ages and male status of adult polar bears. Environmental Monitoring by Svalbard and Jan Mayen (MOSJ), September 8. http://www.mosj.no/en/fauna/marine/polar-bear.html

Peacock, E., Taylor, MK, Laake, J. and Stirling, I. 2013. Population ecology of polar bears in Davis Strait, Canada and Greenland. Wildlife Management Magazine 77:463–476

Rode, KD, Peacock, E., Taylor, M., Stirling, I., Born, EW, Laidre, KL and Wiig, Ø. 2012. The story of two polar bear populations: ice habitat, harvest and body condition. Ecosystem population 54:3-18. http://link.springer.com/article/10.1007/s10144-011-0299-9

Rode, KD, Regehr, EV, Douglas, D., Durner, G., Derocher, AE, Thiemann, GW and Budge, S. 2014. Differences in the response of Arctic top predators to habitat loss: feeding and reproductive ecology of two polar bear populations. Global change biology 20 (1):76–88.

Rode, KD, Wilson, RR, Douglas, DC, Muhlenbruch, V., Atwood, TC, Regehr, EV, Richardson, ES, Pilfold, NW, Derocher, AE, Durner, GM, Stirling, I., Amstrup, SC, St. Martin, M., Pagano, AM and Simac, K. 2018. Spring fasting behavior in cetaceans provides an indicator of ecosystem productivity. Global change biology 24 (1): 410-423.





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