| sea ice. For the polar bear (Ursus maritimus), early ice melting and late seasonal ice formation increases duration of the adverse period. Ice melting is accompanied by a shift of the ice–water boundary towards the deepwater Arctic basin, where food accessibility is lower and polar bears are forced to go to land. In 1994–1997, female polar bear ice habitats in the western Russian Arctic, the Kara Sea, were studied using the Ocean-01 synchronous satellite to determine the ice type and concentration preferences of these animals [1]. The data of this report suggest that in the Kara Sea, in summer, polar bears are moving in the northeastern direction. The same is supported by the results of our interviewing in 2010 of the Cape Sterlegov station staff, who observed the polar bear movement along the Kara Sea coast from west to east. However, there is no comprehensive survey of reasons for such a movement of polar bears. Much attention is paid to the polar bear strategy of space use, especially in connection with changes in ice habitats [2–4]. The polar bear female displacements during different seasons have been discussed in a number of reports [5–7] and even the average speed has been estimated for an individual female bear on the way from northern Alaska to Greenland [8]. But it is still unclear how migration of an individual animal depends on the ice break-up timing. The object of this study was to determine the influence of the arctic marine phenology on the direction of the polar bear movement. A polar bear female has been tagged by a satellite transmitter and the trajectory of its movement was studied in relation to the sea-ice break-up onset date in the coastal zone of Taimyr Peninsula in eastern part of the Kara Sea. In the framework of a project for the polar bear tagging by the satellite transmitters on the Pyasinsky Bay islands, the Kara Sea, an adult female and its yearling cub were immobilized on May 22, 2012, at 8:43 a.m. UTC. The search for a suitable animal was conducted on board of a Mi-8MTV helicopter above the stable fast ice 5 km away from its edge (to prevent that a polar bear gets into water after the drug administration). The animal was immobilized by a combination of medetomidine (Domitor preparation from ORION, Finland, 40 μg/kg body weight) and a mixture of tiletamin/zolazepam (Zoletil preparation from Virbak, France, 3 mg/kg), which were administered using a DAN-Inject JM-25 distant injector (DAN-INJECT, Denmark). After immobilization, the animal state monitoring was conducted permanently every five minutes up to restoration of motor activity. After completion of the procedures, the antidote Antipamezol was administered (Antisedan from ORION) at a dose of 10 mg per animal. |