Here is the March 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 March 2014 is copied below (Fig. 1).
Compare this to February’s map (Fig. 2) – you’ll be surprised at how little has changed!
Figure 1. From original caption: “Movements of 5 satellite-tagged polar bears for the month of March, 2014. Polar bears were tagged in 2013 on the spring-time sea ice of the southern Beaufort Sea. All 5 of these bears have satellite collar transmitters.” Note that the dots with the polar bear icons are the end points (end March), while the other end of the string is their position in early March. These are the same 5 females that were present in January. Click to enlarge.
Figure 2. Movements of 5 satellite-tagged polar bears for the month of February, 2014. Courtesy USGS.
A few things to note:
The female with the teal green track, who was on the September map but disappeared during October and then returned during November and December, is still in the Chukchi Sea. The track of this bear is a reminder that a signal that disappears from the area isn’t always due to transmission failure.
It may be possible that she is in a maternity den built on the sea ice and that her movements are reflecting sea ice movements. It’s really hard to say for sure from the maps.
One of the four females (dark purple) on the north coast of Alaska, east of Barrow, has not moved since November. It looks like this female, and the yellow dot female, were pregnant when collared in July and spent the winter in dens with newborn cubs. Yellow female is on the move, out on the ice, but dark purple has not moved.
The two other females (royal blue and pink) have been moving around a bit along the coast of Alaska east of Barrow since November (see Fig. 2 below).
See the January map below (Fig. 3) for comparison.
More on how movements of polar bears of this region affects population estimates here.
Figure 3. Movements of 5 satellite-tagged polar bears for the month of January, 2014. There were two fewer females present in January than there were present in November and December. Courtesy USGS.
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