RADIO TRANSMITTERS BIAS ESTIMATION OF MOVEMENTS AND SURVIVAL

During 1987 and 1988, we tested the hypotheses that radio transmitter size (14 vs. 18-22 g) and signal strength (1-stage vs. 2-stage) had no effect on estimates of survival, movement, or home range of 54 female greater prairie-chickens (Tympanuchus cupido). Birds (n = 33) wearing heavier 2-stage solar transmitters, with twice the reflective surface, had lower (P = 0.08) estimated annual survival than birds (n = 21) wearing the lighter transmitter. In 2 of 3 seasons, estimates of daily movements, within-day movements, and seasonal ranges were larger (P < 0.09) for birds equipped with the more powerful 2-stage transmitters. Differences in estimated movements and home range did not represent true differences because long distance movements were more likely to be detected for birds wearing 2-stage units than for those equipped with 1-stage transmitters.