POTVIN DOUBLE-COUNT AERIAL SURVEYS IN NEW BRUNSWICK: ARE RESULTS RELIABLE FOR MOOSE?

Abstract

Following the rapid decline of deer (Odocoileus virginianus) across northern New Brunswick in the late 1980s, the New Brunswick Department of Natural Resources began to utilize a double-count helicopter survey to estimate deer numbers. Although the survey was designed for deer, moose (Alces alces) sightings were also recorded; however, no analysis was conducted on the accuracy or usefulness of these data to estimate moose numbers. The survey design was a modification of the Potvin double-count survey method for deer which accounts for most caveats to aerial surveys. This double-count (mark-recapture) technique allows calculation of bias for both observers, for single and groups of moose, and individual flights. Moose population estimates calculated from 79 flights ranged from 0.17-3.49 moose/km2 and were similar to a variety of estimates throughout North America. Population estimates from 2004-2009 correlated well with corresponding 2009 population indices for moose based on number of moose seen by deer hunters (Corr. = 0.725, P <0.001). The Potvin estimates in Wildlife Management Zone 2 were highly correlated (0.82-0.93, P <0.05) with other indices based on road kill moose, moose sightings, and harvest success rates; moose sightings and hunter success were also correlated in several other zones. This analysis indicates that Potvin surveys produce reliable population density estimates of moose in boreal/Acadian forests, given that the sighting probability is >0.4 and flights occur before mid-February when moose may occupy denser canopy cover.