The shore of Alaska is not very important to Southern Beaufort polar bears – most of them stay on the sea ice during the summer and early fall, where they may or may not continue eating. These results of on-going satellite tracking studies by USGS1 confirm results of previous studies.
Figure 1. Original caption: “Movements of 4 satellite-tagged polar bears for the month of September, 2015. Polar bears were tagged in 2014 and 2015 on the spring-time sea ice of the southern Beaufort Sea. All 4 of these bears have satellite collar transmitters. Polar bear satellite telemetry data are shown with AMSR2 remotely-sensed ice coverage for 30 September, 2015.” Click to enlarge. Original image here.
[Compare to August 2015 here; September 2014 here]
In fact, most Southern Beaufort Sea polar bears spend their entire lives at sea, with about half of all pregnant females denning on the sea ice. Chukchi Sea bears are likely similar.
Working between 2000 and 2005, Schliebe and colleagues (2008:1005) found that an average of 3.7% (three point seven, not a typo) of all polar bears (out of an estimated 1,526 bears) spent time on land in fall (mid-September to end of October). That’s 56 bears, per year, on land in the fall – out of 1,526 or so bears.
Note the fat bears that turn up at Kaktovik are part of these few bears that stay onshore in summer. Kelsey Eliasson (PolarBearAlley) recently reported seeing about 20 bears at Kaktovik out of perhaps 40 present this year at the end of September (see below), i.e., a small percentage of the total Southern Beaufort population.
Eliasson tweet posted 30 September 2015 below:
Eliasson Facebook entry posted 2 October 2015 below (these are bears in excellent condition!):
Eliasson Facebook entry posted 30 September 2015 below:
Footnote 1. This is the August 2015 follow-up to my post on the July 2013 track map for female polar bears being followed by satellite in the Beaufort Sea by the US Geological Survey (USGS) – “Ten out of ten polar bears being tracked this summer in the Beaufort Sea are on the ice.” See that post for methods and other background on this topic, and some track maps from 2012 (also available at the USGS website here).
References
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. http://link.springer.com/article/10.1007/s00300-008-0439-7
END
You must be logged in to post a comment.