46 



FISH AND WILDLIFE TECHNICAL REPORT 30 



resulted in very different conclusions (Fig. 42B). Here, 

 dependence among successive locations seemed to 

 be only a minor problem. However, locations from a 

 mule deer in Idaho were far from achieving independence, 

 even when locations were restricted to one every two days 

 (Fig. 42C). 



Time of Sampling 



Many analyses require that locations be a random sam- 

 ple of all the true locations of an animal. Most duty cycles 

 we used were regular that is, transmissions occurred at 

 the same time during each transmission-day. Thus, sam- 

 pling was more nearly systematic than random. Systema- 

 tic sampling can sometimes be substituted for random 

 sampling with little adverse effect, although problems can 

 arise when systematic sampling matches an existing pat- 

 tern. Such a situation may occur when sampling locations 

 at regular intervals, especially with duty cycles having a 

 24-h period or integer multiple thereof. Many species 

 display circadian rhythms that may coincide with such 

 sampling periods (Swihart and Slade 1985a), potentially 

 biasing the data. 



Cost Comparisons 



In some situations, satellite telemetry may be the only 

 means of acquiring data necessary to meet study objec- 

 tives. In most cases conventional telemetry may also be 

 used, and the costs of the two approaches may be a factor 

 in determining which is best for a particular study. Unfor- 

 tunately, it is not possible to make a single cost compari- 

 son between satellite and conventional telemetry, because 

 costs can vary greatly between different study areas for 

 animal capture, air charter, and other factors. Each re- 

 searcher must determine the costs for their own study. 



The following hypothetical cost comparisons were 



based on three situations where satellite telemetry was 

 used as an alternative to conventional telemetry (Table 

 17). Satellite collars, each including a VHP transmitter, 

 were assumed to cost $3,300 each and were to be replaced 

 3-4 times during a 5-year study, given a transmitter life of 

 12-18 months. Each VHP transmitter cost $330 and had 

 an assumed life of 3 years, needing replacement only once. 

 Then, a second transmitter was purchased for each animal 

 to replace the used collar when the animal was recaptured. 

 The Argos processing fee was assumed to be $8.22/day 

 per transmitter, or $3,000 per transmitter-year. Labor costs 

 were not included in these examples. 



These examples suggested that satellite telemetry is 

 most cost effective in situations where air charter costs are 

 high and a large area must be searched to relocate all radio- 

 collared animals, as with the Porcupine caribou herd (Fig. 

 43). In this example, we assumed that caribou could be 

 anywhere within the herd's range during each tracking 

 flight. Therefore, the entire range required searching re- 

 gardless of the number of radio collars deployed, and the 

 per-animal cost to relocate caribou when 50 collars were 

 deployed was 20% of the cost to relocate 10 collars. We 

 also assumed that location accuracy was comparable to or 

 better than that obtained using satellite telemetry and that 

 each radio-collared caribou therefore had to be located 

 visually. Given these assumptions, satellite telemetry was 

 cost effective if study objectives required more than three 

 (n = 10) caribou or 13 (n = 50) locations per year. If daily 

 locations were needed, costs using VHP telemetry were 43 

 (n - 10) or 10 (n = 50) times higher than those using 

 satellite telemetry. 



Radio-tracking costs in the Kodiak Island brown bear 

 example (Fig. 44) were only 5% of those in the first 

 example because of the smaller size and location of the 

 study area, and lower air charter costs. Satellite transmit- 

 ters were programmed to transmit only one day each week 

 in winter while the bears were in their dens, and therefore 



Table 17. Cost comparison between satellite and VHP telemetry systems for hypothetical 5 -year studies of 3 species. 



"Cost to cover entire range of Porcupine caribou herd regardless of number of collared animals. 

 b First time capture cost per deer using Clover traps. 

 c Second time capture cost using helicopter and net gun. 



