Tracking polar bears in the Beaufort Sea: February map

Here is the February 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 February 2014 is copied below (Fig. 1).

The five bears that were being tracked in January are still present — down 50% from the ten bears collared in July.

Figure 1. From original caption: “Movements of 5 satellite-tagged polar bears for the month of February, 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 January), while the other end of the string is their position in early February. These are the same 5 females present that were present in January. Click to enlarge.

Figure 1. From original caption: “Movements of 5 satellite-tagged polar bears for the month of February, 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 February), while the other end of the string is their position in early February. These are the same 5 females that were present in January. Click to enlarge.

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. That’s the general direction the sea ice seems to flow (see animation here) but would it move a den that far in three months? I’m guessing maybe not but I could be wrong.

Two of the four females (yellow and dark purple) that are onshore on the north coast of Alaska, east of Barrow, have still not moved since November. It’s probably safe to conclude that these two females were pregnant when collared in July and are now in dens with newborn cubs.

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) – rather more than would be expected, I think, from mothers in maternity dens built on sea ice.

See the January map below (Fig. 2) for comparison.

Figure 2. From original caption: “Movements of 5 satellite-tagged polar bears for the month of January, 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 January), while the other end of the string is their position in early January. There were two fewer females present in January than there were present in November and December. Click to enlarge.

Figure 2. From original caption: “Movements of 5 satellite-tagged polar bears for the month of January, 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 January), while the other end of the string is their position in early January. There were two fewer females present in January than in November and December. Click to enlarge.

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