32 FISH AND WILDLIFE TECHNICAL REPORT 30 



northwestern Alaska. However, when the position of this 

 transmitter was deliberately treated as an unknown, the 

 nearest transmitter that could be used for reference was 

 near Fairbanks more than 800 km away. Under these 

 circumstances, the median location error from a randomly 

 chosen sample of 200 location estimates fell to 17 km, and 

 the mean fell to 47.4 km. More than 18% of these locations 

 were > 100 km from the true location, and only 2.5% were 

 within 2 km. 



Cost Comparison 



The primary advantages of a LUT compared to standard 

 Argos processing are ( 1 ) avoidance of the usual 3-5-h 

 delay for data processing; (2) greater processing flex- 

 ibility; and (3) reduced cost for some applications. The 

 cost of a LUT is approximately $20,000-40,000. A system 

 using S-band transmissions and a more sophisticated 

 tracking antenna costs about $65,000. LUT users must still 

 pay Argos for use of the system, although the minimum 

 rate is only 25% of the standard processing cost. Users 

 who request archived data for a particular month will be 

 charged for a full month of standard processing plus a 

 service fee. 



In situations where reduced data quantity and location 

 accuracy are acceptable, a LUT can be cost effective for 

 studies that involve as few as five PTT's. For example, 

 assuming the processing charge assessed AFWRC during 

 1987, the purchase price of our LUT was equivalent to the 

 annual processing cost for 10 PTT's transmitting daily. 



Field Studies 



Caribou: Northern Alaska and Yukon 



Since 1985, the AFWRC and ADFG have used satellite 

 telemetry to monitor the daily movements and activity 

 of caribou of the Porcupine and Central Arctic herds in 

 northern Alaska and northwestern Canada. The informa- 

 tion is used to assess potential effects of oil and gas devel- 

 opment within the Arctic National Wildlife Refuge 

 ( AN WR) on caribou and to mitigate the effects of chang- 

 ing land use and resource management practices. 



Between 1985 and 1987, more than 49,000 locations 

 and 79,000 sets of sensor data (temperature and activity) 

 were obtained for 34 adult female caribou using satellite 

 telemetry. Caribou were captured on winter range when 

 immobilizing drugs contained in a dart gun were fired 

 from a helicopter. The 1 .5-1 .6-kg collar package included 

 a conventional VHP transmitter that was used to relocate 

 the caribou by aircraft. PTT's were programmed to trans- 



mit 6 h/day or, in the case of 13 third-generation PTT's, 12 

 h/day between 1 May and 30 September and 6 h every 

 other day during the rest of the year. These duty cycles 

 gave a theoretical battery life of 1 year. Five of 42 PTT's 

 deployed on caribou before October 1986 experienced 

 message failure within 6 months of deployment. A mean 

 of 3.5 locations per day was obtained for caribou with 

 second-generation PTT's. Caribou with third-generation 

 PTT's were located 8.0 times daily between May and 

 September. 



Daily movement rates of radio-collared caribou from 

 the two herds which differ greatly in size (165,000 

 versus 16,000 caribou) and separation of seasonal 

 ranges were similar except during spring and fall migra- 

 tions (Fancy et al. 1989). In both herds, movement rates in 

 July exceeded those during migration. The annual dis- 

 tances traveled by caribou cows ranged to 5,055 km; these 

 were the longest movements recorded for any terrestrial 

 animal. 



We considered satellite telemetry a useful research tool 

 for our caribou studies. We were satisfied with the rela- 

 tively low failure rate and high efficiency of data-gather- 

 ing at these latitudes, and we considered that location 

 precision was adequate for our objectives. 



Polar Bear: Beaufort Sea 



Polar bears occupy one of the most remote habitats in 

 the world the polar ice cap. The pack ice substrate is in 

 constant motion, and there are no permanent fuel caches or 

 logistics bases on its surface. Further, only the Cetacea and 

 some members of the Pinnipedia range more widely than 

 polar bears. Satellite telemetry was used to gather data on 

 polar bear movements and activities that would not other- 

 wise be obtainable. Forty-four PTT's were deployed on 

 polar bears in the Beaufort Sea beginning in spring 1985. 

 Through June 1988, 10,547 locations and 128,038 activity 

 and temperature data were recorded. 



Satellite telemetry provided information on maternity 

 den entry and emergence dates of polar bears. Polar bears 

 in dens maintain consistently warmer temperatures than 

 those not in dens, sleep most of the time, and move very 

 little. We used activity and temperature sensors within 

 PTT's to provide clues to entrance and emergence times. 

 We documented dates of den entrances for 22 polar bears 

 using these data; however, because many PTT's failed to 

 reach the end of their expected lifetime, we documented 

 emergence times for only seven of these bears. Also, 

 PTT's often did not provide locations of denning those 

 positions that were fixed during denning tended to be 

 inaccurate. One den that was visited in 1988 was consis- 



