Here is the December 2014 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). The USGS track map for December is copied below.
There are only 10 bears being followed now, which means a few more collars have failed, or the bears have moved out of the area or died.
Original caption: “Movements of 10 satellite-tagged polar bears for the month of December, 2014. Polar bears were tagged in 2014 on the spring-time sea ice of the southern Beaufort Sea. All ten of these bears have satellite collar transmitters. Polar bear satellite telemetry data are shown with AMSR2 remotely-sensed ice coverage for 31 December, 2014.” Click to enlarge, original image here.
Three out of the remain ten Southern Beaufort bears (30%) were actually in Chukchi Sea territory at the end of December, with one appearing to be headed into the Bering Sea and another was located to the far north (west of Point Lay, see discussion here). [If you missed it, my October 2014 post on the progress of these bears has some maps from previous years that are worth reviewing]
Another female is well offshore on the winter ice north of Prudhoe Bay in the Southern Beaufort Sea, while the remaining six are either onshore or nearshore along the north shore of Alaska. Three of those look like they haven’t moved all month (one dot is obscured by the light blue dot near Kaktovik) and may be holed up in maternity dens.
The other three nearshore females have moved relatively little over the month. That means they could be feeding but it’s also possible one or more of them have made dens on the nearshore ice. If they have made dens on the ice nearshore, it would mean their movements have been passive (i.e., the dens have simply moved with currents and winds that push the ice).
That may also be true for a few of the other bears shown out on the ice at this time of year, especially those that have moved only a little over the last month.
[December is the month when most polar bears give birth]
Compare the December map above to last month, copied below (November 2014, described here).
Original caption: “Movements of 12 satellite-tagged polar bears for the month of November, 2014. Polar bears were tagged in 2014 on the spring-time sea ice of the southern Beaufort Sea. All twelve of these bears have satellite collar transmitters. Polar bear satellite telemetry data are shown with AMSR2 remotely-sensed ice coverage for 30 November, 2014.” Click to enlarge, original here.
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