FISH AND WILDLIFE TECHNICAL REPORT 30 



May 1988, 289 PTT-months of data were removed from a 

 possible 318 PTT-months (91%). We do not know why 

 this group of PTT's had a lower survival rate: not 1 of the 

 10 collars deployed in March 1987 lasted for a full year, 

 and mean operating time for this group of PTT's was 

 approximately 33 weeks. 



One of four deployments on muskoxen in northern 

 Alaska experienced message failures almost immediately. 

 It was redeployed after being refurbished and has since 

 operated continuously for 12 months. One of two musk- 

 oxen collared in Greenland experienced a location fail- 

 ure just after the investigator departed. This PTT was 

 deployed on a bull, and we suspect that abuse incurred 

 during the rut was responsible for its failure. This PTT 

 began operating again by itself some 1 months after 

 deployment. 



The first small PTT powered by C-size batteries and 

 weighing 1 .2 kg was deployed on a wolf in the ANWR; 

 it failed after 1 .5 months. However, a similar PTT placed 

 on another wolf transmitted for 15 months, 7 months 

 longer than expected. As of October 1988, none of the 

 PTT's deployed on elk, mule deer, or Dall sheep had failed 

 before expected battery depletion. One of two PTT's de- 

 ployed on moose experienced message failure after ap- 

 proximately 10 months. 



Eight PTT's have been deployed on walruses since 

 summer 1987. The longest operation time for any of the 8 

 was 4.5 months; the others have experienced either loca- 

 tion or message failures within 4 months. Although rea- 

 sons for failure are still unknown, it seems that current 

 hardware configurations for walruses are not capable of 

 providing the > 1-year expected life span typical of most 

 terrestrial species applications. 



Eleven PTT's were deployed on brown bears in Alaska 

 during summer 1987. Eight of these were expected to 

 function through May 1988, and three were expected to 

 function through September 1988. One bear shed its collar 

 in August 1987. No data were received following den 

 entrance from 9 of the 10 remaining bears. We initially 

 assumed that PTT signals were blocked by the dens. How- 

 ever, following den emergence, we received data from 

 only one PTT and it ceased functioning within 3 weeks. 

 Three of the eight PTT's were designed to cease transmit- 

 ting during denning but resume in spring. An error in 

 programming the duty cycles for these three prevented 

 resumption of transmissions. 



Between spring 1985 and spring 1988, 109 PTT's were 

 deployed on polar bears in the Beaufort, Bering, and 

 Chukchi seas (Garner et al. 1989). Five models of PTT's 

 were used. Versions A and B of second-generation PTT's 

 differed in their duty cycles. Versions A, B, and C of third- 

 generation PTT's each contained various hardware and 

 software improvements over previous models. 



In most cases, location failures preceded message fail- 

 ures. Both of the two generation 2A PTT's failed before 

 the expected battery life of 288 days. Location failures 

 occurred after 197 and 283 days; message failures oc- 

 curred after 244 and 283 days. All five generation 3A 

 PTT's experienced location failures before the end of their 

 expected 414-day battery life, although one location fail- 

 ure occurred on day 411. Three of the five exceeded the 

 expected battery life for messages only. 



Survival rates were similar for the 30 2B and 30 3B 

 models (Fig. 4); however, 3B PTT's appeared to perform 

 slightly better than the 2B PTTs. More 3B PTT's than 2B 

 PTT's provided both location and sensor data throughout 



Fig. 4. Survival curves of Model 2B and 3B 

 platform transmitter terminals (PTT's) on 

 polar bears in the Beaufort, Chukchi, and 

 Bering seas, 1986-88. 



O) 



CO 



i 

 0) 

 Q. 



O 

 CO 



120 



100 



Expected Battery Life 



Model 2B Location 

 Model 2B Data only 

 Model 3B Location 

 Model 36 Data only 



100 200 300 400 

 Days since Deployment 



500 



