The long migra­ti­on of polar bear Kara

Polar bears in Spits­ber­gen are tag­ged with satel­li­te trans­mit­ters every year by the Nor­we­gi­an Polar Insti­tu­te. It is pos­si­ble to fol­low some of them on a WWF web­site on their migra­ti­ons.

In many cases, the fema­le bears stay within a more or less limi­t­ed area for quite some time. But polar bear Kara has recent­ly bea­ten all records: tag­ged in Janu­ary 2013 on a gla­cier bet­ween Horn­sund and Ham­berg­buk­ta on Spitsbergen’s east coast, she made a migra­ti­on of an incre­di­ble 3703 km within less than a year. She star­ted towards Nova­ya Zem­lya and then went north towards Franz Josef Land, but so far wit­hout going on land any­whe­re. She then went even fur­ther east to Sever­na­ya Zeml­ja, whe­re she final­ly spent some time ashore after having crossed the Kara Sea com­ple­te­ly. Kara final­ly went west again to Franz Josef Land, whe­re the sen­der stop­ped trans­mit­ting data. She might have gone into a snow cave to give birth to polar bear babies – may­be she is hap­py mother of two litt­le polar bears by now …?

The fema­le polar bear Kara was, at the time of tag­ging, 13 years old, 2.2 m long and weighs a mode­ra­te 217 kg.

Gene­ral­ly, data from the most recent tag­ging sea­son in spring 2014 may sug­gest that fema­le polar bears have curr­ent­ly got less off­spring than in other years: only 3 out of 29 fema­les had cubs in their second year, the nor­mal rate should be some­whe­re near one third. But the total num­ber is too low to ful­ly exclude coin­ci­dence.

Mar­king and tag­ging polar bears is con­tro­ver­si­al, as tran­qui­li­zing the bears while fol­lo­wing them with a heli­c­op­ter is quite stressful for the ani­mals and the­re are cases when the bear did not sur­vi­ve. This hap­pen­ed in Octo­ber 2013 on Edgeøya (eas­tern Spits­ber­gen) and pos­si­bly again in April 2014. In the lat­ter case, howe­ver, the exact cau­se of death is not yet cer­tain. In spring 2014, a total of 73 polar bears have been tran­qui­li­zed and exami­ned in Spits­ber­gen.

Source: WWF, Sval­bard­pos­ten

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