APPLICATION OF A DOUBLE-COUNT AERIAL SURVEY TECHNIQUE FOR WHITE-TAILED DEER, ODOCOILEUS-VIRGINIANUS, ON ANTICOSTI-ISLAND, QUEBEC

We applied a double-count aerial survey technique over six surveys con ducted during two winters and two summers on Anticosti Island, Quebec. A total of 2532 White-tailed Deer (Odocoileus virginianus) belonging to 2046 groups was counted inside 704 0.36-km2 Strip plots (6 km x 60 m) by two independent observers located on the same side of a helicopt er. Dea groups were classified according to activity (moving or not), forest cover (open or closed), and position relative to the aircraft ( under or beside). The sighting probabilities of the groups were comput ed using the model underlying the Petersen estimate. Sighting probabil ities were 0.56 for single deer and 0.81 for groups of two or more dee r. Single deer were more visible when moving or located in the open. A s compared with a conventional single-count aerial survey, the double- count technique increased the estimated deer number by 35% (uncorrecte d) due to the second observer and by 58% when corrected by the Peterse n model. A corrected deer estimate was derived for single deer and gro ups of two or more deer, separately, and the total deer population was obtained by summing those two values. The estimated density varied be tween 8.2 0.98 and 20.6 +/- 1.79 deer/km2 (xBAR +/- SE), depending on the survey.