USE OF THERMAL INFRARED SENSING - TO ESTIMATE DENSITY OF WHITE-TAILEDDEER

We estimated density of white-tailed deer (Odocoileus virginianus) usi ng spotlight surveys and aerial surveys with an infrared (IR) sensing system at Sand Lake National Wildlife Refuge in South Dakota. Thermal IR sensing detected 88.2% of deer counted by ground personnel. In 1993 , density estimates (17.0, 15.8, 16.6 deer/km(2)) were calculated usin g 3 sets of non-overlapping transects to reduce biases (i.e., double-c ounting, deer movement, and deviation from transect) associated with o verlapping transects. Variation in density estimates obtained from aer ial surveys using IR conducted in February 1994 with uniform snow dept h and May after snow melt was low (CV = 10.3%). Spotlight counts assoc iated with IR sensing flights underestimated deer density by 38%. High detection rates and increased estimates from IR sensing indicated tha t IR sensing was a more reliable density estimator than spotlight surv eys. Although cost of IR sensing in 1993 ($99/km(2)) was about 4-fold higher than cost of visual aerial transect sampling, in areas where cu rrent methods of estimating density are questionable, estimating densi ty by IR sensing is justifiable.