Here is the October follow-up to my post on the July 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).
The track map for October is copied below (Figure 1).
By the end of October, ice reached the coast in several areas. The ten bears from July were down to seven – 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).
A few things to note:
The female that was on Banks Island at the end of September (light brown) is now back on the ice but still in the Northern Beaufort subpopulation region.
During October, the dark brown female made her way across the ice from the Southern Beaufort to the Chukchi Sea subpopulation region.
Three females were so close together on the shore (near Prudhoe, Alaska) during September that their dots overlapped (and lack of tracking “strings” means they didn’t move much). During October, two of these three bears made their way east toward Kaktovik.
The female represented by the light green dot and tracking string spent September and most of October at the southern edge of the pack ice but by the end of October, she seemed to be heading towards land.
Finally, and most significantly, despite the fact that all of these bears were tagged in the spring (mating season for polar bears) in the Southern Beaufort, two of the seven now being tracked have left the region: one to the Northern Beaufort and one to the Chukchi Sea subpopulation region. These regional boundaries are known to be crossed — here you see it in action.
The map for September 2013 is below, for comparison: