TRACKING WILDLIFE BY SATELLITE 



33 



Fig. 29. Movements of female polar bears in 

 the Chukchi and Bering seas (A) and the 

 Beaufort Sea (B), May 1985-May 1988. 



Alaska \ Canada 



\ 



60O \ 



B. 



tently positioned by the satellite 11.1 km from its actual 

 location. 



Much of our existing knowledge of the seasonal and 

 annual movements and distribution of Beaufort Sea bears 

 has been obtained using conventional telemetry in recent 

 years. Conventional telemetry has shown that although 

 polar bears are seasonal to general regions or activity 

 areas, these areas are extremely large, sometimes exceed- 

 ing 259,000 km 2 . Satellite telemetry has expanded our 

 knowledge of the size of these activity areas (Fig. 29). 



Satellite telemetry has also, in some cases, provided 

 details needed to determine the purpose of some of the 

 longest movements. For example, in previous years, some 

 bears wearing VHP transmitters were radio-tracked in 

 northwesterly directions until they were beyond the range 

 of survey aircraft or until they entered the waters of the 

 Soviet Union. We suspected that those bears were moving 

 to the stable ice of the polar basin to den, because food is 

 scare far offshore and foraging is therefore difficult. Ac- 

 tivity and temperature sensor data received from satellite 

 collars has confirmed our hypothesis that many of those 

 bears traveling far offshore were seeking and entering 

 maternity dens. 



Similarly, during winter 1986, many collared bears 

 moved to locations southwest of Point Barrow, Alaska 

 areas where we had not seen them before. Contradicting 

 this, however, were activity and temperature data trans- 

 mitting from some of these "moving" bears, suggesting 

 that they were in maternity dens. Therefore, we hypothe- 

 sized that unusual currents that year in the southern Beau- 

 fort Sea had passively carried bears that had denned on the 

 ice. This hypothesis was subsequently corroborated by 

 aerial telemetry. 



Because of the high costs of using aircraft with conven- 

 tional telemetry, we are limited to 5-6 survey flights each 

 year. With satellite telemetry, we can obtain much more 

 detailed movement data, although it is on a smaller sample 

 of bears. Future applications that may make use of such 

 detailed data include studying the relations between 

 movements of the sea ice and those of polar bears. Cur- 

 rently, however, the unreliability and relatively short life 

 span of PTT's limits our ability to conduct such a study. 

 Studies requiring frequent visual relocations of marked 

 individuals (e.g., predator-prey relations) may potentially 

 be made more feasible by satellite telemetry because in- 

 vestigators can fly directly to the animals, rather than 



