COMPARISON OF 3 METHODS FOR EVALUATING ACTIVITY OF DALL SHEEP

Validation of the reliability of remote-sensing data is critical to subsequent analyses, yet is often neglected. Thus, we assessed the efficacy of 3 methods of collecting information on activities of captive and free-ranging Dall's sheep (Ovis dalli) in Alaska. Conventional very high frequency (VHF) radio-telemetry transmitters and platform transmitter terminals that transmit to satellites, each with motion-sensitive tip-switches, were compared with simultaneous direct observation. Both VHF (98% agreement) and satellite telemetry (98% agreement) reliably distinguished active from inactive behaviors for free-ranging females. For activity of a free-ranging male, rate of agreement with direct observation was lower (P < 0.05) by satellite telemetry (89%), but not by VHF telemetry (98%). Neither telemetry method could reliably distinguish standing from lying or feeding from walking. Satellite telemetry was most cost effective when a large amount of data was required from each animal. Direct observation was most cost effective when few samples were required from each animal and when access and visibility were good.