Performance of 2 models of satellite collars for wolves

We compared the performance of 2 different models of Argos-certified satell ite transmitters (ST-14, and ST-10, Telonics inc., Mesa, Ariz.) designed fo r use on wolves. Prototypes similar to the ST-14 collar have been used succ essfully on wolves in northwest Alaska. However, the ST-10 collar has only recently been evaluated on coyotes and resulted in few inconsistent locatio ns. We deployed 15 ST-10 collars and 8 ST-14 collars on adult wolves in 18 different packs in 1997-98. ST-10 collars are lighter (ca. 380 g) and trans mit at 0.4 watts, whereas the ST-14 collars transmit at 1 watt. Specificall y, we examined: 1) number of locations obtained for each collar per 7-hour duty cycle (period during which the collar is transmitting), 2) number of l ocations in each accuracy class (Argos location quality index, NQ=1-3), and 3) whether number of locations/duty cycle declined as the collars approach ed their theoretical life expectancy. ST-14 collars produced more locations per hour duty cycle than ST-10 collars, with ST-14 collars averaging (SE) 1.33 (0.17) and ST-10 collars 0.54 (0.07) locations/duty cycle. Due to the lower power demand of ST-10 collars, twice the number of duty cycles can be achieved and therefore a similar number of locations was received througho ut the lifetime of both collar types. ST-10 and ST-14 collars produced a si milar number of locations within each accuracy class. We did not detect a d ecline in number of locations generated/duty cycle for either collar type a s their life expectancy was approached. Costs averaged (US)$53 and $46/loca tion for the ST-14 and ST-10 collars, respectively. We conclude that using the lighter, smaller, and less expensive ST-10 collar is the better choice for many researchers.