Here is the follow-up to my post on the July track map for 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).
The track map for September was posted on the USGS website on October 17 (delayed due to the US government shutdown) and is copied here below (Figure 1). The ice rebounded during the second half of the month (after the annual minimum was reached on September 13). The ten bears from July were down to eight – their collars might have stopped working or fallen off (most likely), they might have left the area entirely (also possible) or they might have died (the researchers don’t say which).It appears that of the eight polar bears still being followed by USGS researchers in September, four are on shore and four are still on the ice. Only time will tell if the four females on shore are pregnant and preparing maternity dens for the winter, but this seems the likely reason they are not on the ice with the others.
One very interesting point worth noting: the one bear (light brown) captured onshore in the Southern Beaufort subpopulation region in the spring of 2013, has moved into the Northern Beaufort subpopulation region, on Banks Island (see map here), and may be denning there. This inter-subpopulation movement is relatively uncommon.
The map for July 2013 is below, for comparison: Continue reading