10 FISH AND WILDLIFE TECHNICAL REPORT 30 



Table 6. Performance indices (with their coefficients of variation [CV] in parentheses) and study locations for platform 

 transmitter terminals (PTT's) on various species, April 1987 '-September 1988. Sample sizes are the number ofPTT- 

 months used in calculations. 



of 0.78 for muskoxen on Alaska's north slope. Variation of tude (Fig. 1). Both the elk and mule deer studies, con- 

 indices was made up of both within- and among-PTT ducted at temperate latitudes, displayed comparatively 

 components. In some cases, we were able to identify con- l w performance indices. 



sistent differences in the performance of PTT's deployed We found no evidence that extremely low temperatures 

 on similar animals in similar habitats. For example, the affected PTT efficiency. As measured by the location in- 

 high coefficients of variation (CV) for the two muskoxen dex ' caribou in northern Alaska and northern Yukon dis- 

 in Greenland and the two elk in Yellowstone National Park P la y ed no tendency toward lower efficiency in winter than 

 were largely due to marked differences in the overall per- in summer < F = L584 ' df = 8 ' 126 ' P > ' 10; Fl 8' 5) ' On 

 formance between the two PTT's in both cases. These Alaska '. s n rth sl< * e ' skoxen ' which used similar habi- 

 ,., ,, . tats at similar latitudes during summer and winter, showed 

 differences may have been caused by internal hardware ... c , r, 



. ,._, - , no seasonal patterns in either performance index. Rey- 



mconsistencies, subtle differences in attachment of the ., /ir . or ., , . f , 



.._ . . nolds (1989) had reported a drop in the number of loca- 



collartotheammal,differ,ngbehav,orsorhabitatsusedby ^ winter for & first . generation PTT; however> 



the two animals, or some combination of these and other third . generation pT T ' s evidently suffer no loss of efficien- 



factors. In other cases, total vanation was due partly to cy during cold weather 



among-PTT differences and partly to among-month dif- " In some cases PT T performance appeared to decline 



ferences (Fig. 5). over t j me p or example, message indices from all 10 



Both performance indices were positively correlated pyj's deployed on polar bears in the Chukchi Sea during 



with mean latitude of the study area (message index: spring 1987 had negative slopes when regressed on time, 



Spearman r^ = 0.703, P < 0.01 ; location index: Spearman r s and 1 4 of 1 8 location indices from 1 988 Chukchi Sea bears 



= 0.945, P < 0.001; Fig. 6). The positive correlation was also declined with time. Figure 7A provides a typical 



expected because satellite coverage increases with lati- example of PTT's from three polar bears in the Chukchi 



