Evaluation of Bias in the Proportion of White-tailed Deer Fawns Sighted from Helicopters

We marked fawns and adult white-tailed deer (Odocoileus virginianus) on 2 south Texas areas during 1986-88. Deer sighted on repeated helicopter flights were evaluated to determine if the age ratio of sightings matched the known ratio of marked fawns-to-adults in the populations. There was a trend toward undercounting fawns on each area.