“Polar bears were tagged in 2013 and 2014 on the spring-time sea ice of the southern Beaufort Sea. Seventeen of these bears have satellite collar transmitters and 7 of these bears have glue-on satellite transmitters” say the folks at the USGS Alaska Science Center.
I guess that’s why the April map was late getting posted.
They explain the work this way:
“The USGS Alaska Science Center uses the latest technology in satellite radio-tracking to fill key information gaps on how polar bears use both the sea ice and land. Adult female polar bears are captured, fitted with satellite telemetry collars, and followed throughout their annual range. In collaboration with the U.S. Fish and Wildlife Service we are also experimenting with glue-on and ear tag satellite transmitters, which can be deployed on adult male bears and younger, still-growing bears.”
See a photo below (Figure 2) of the glue-on transmitter, which goes between the shoulder blades. Only adult females can wear radio collars: the necks of male bears are larger than their heads (so collars slip off) and collars made tight enough to stay on a young bear when deployed would get tighter and tighter as the bear grew. This is why we know far more about the movements of female polar bears than we do about males or subadults.
However, the icons used on the April map (Figure 1) do not distinguish female, male or young animals, so we can’t see which is which.
The information provided also does not say if the five bears tracked on the March map (Figure 3, included below, discussed here) are included in the April map, but it looks like they may be.
Figure 1. From original caption: “Movements of 24 satellite-tagged polar bears for the month of April, 2014. Polar bears were tagged in 2013 and 2014 on the spring-time sea ice of the southern Beaufort Sea. Seventeen of these bears have satellite collar transmitters and 7 of these bears have glue-on satellite transmitters. Polar bear satellite telemetry data are shown with MODIS imagery from 26 April, 2014.” Click to enlarge. Original image here.
Figure 2. From the 2013-2014 issue of “Polar Bear News” (USFWS).
March 2014 tracking map below, for comparison.
Figure 3. 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.
Polar bear photos above from US Fish & Wildlife Service Newsletter, Polar Bear News, the 2010 issue (pdf here) and the 2013-2014 issue (pdf here).
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