Northern Prairie Wildlife Research Center
On 3 February 1998 male wolf 5399 (≥18-mo old) born at Camp Ripley was captured by helicopter net-gunning. A 920 g GPS collar (Merrill et al., 1998) was placed on the wolf and the wolf was released. The collar had been programmed to acquire a GPS location every 3 h. If no location was recorded, the GPS collar tried again in 15 min and 30 min. If all three attempts failed, further attempts were not made until the next programmed interval. We dropped the collar off the wolf via remote signal (Mech et al., 1990), homed in on its VHF signal, collected the collar and downloaded the data (Merrill et al., 1998).
A 560 g satellite collar with a stiff external whip antenna (Microwave Telemetry Inc., Columbia, Maryland) was placed on male wolf 7803 (10-mo old), which had been captured by helicopter net-gunning at Camp Ripley on 1 February 1998. After retrieval and refurbishing, the collar was placed on female wolf 7804 (2-y old; aged by following her with a VHF radio since she was a pup) on 3 February 1999. With both wolves, the collar was programmed for the following duty cycle: first 5 mo, 12 h on (transmitting a signal), 24 h off; remainder of collar life, 12 h on, 72 h off. ArcView© geographic information system (ESRI Inc., Redlands, California) was used to create maps and calculate distances traveled and the number of times wolves crossed state, provincial and interstate highways.