Accuracy of Sex and Age Ratio Counts of White-Tailed Deer

Field counts of white-tailed deer (Odocoileus virginianus) to determine fawn production, adult sex ratio, and population size assume equal observability of all individuals. Similar data from Virginia and Texas showed that there was rarely a period during summer or fall in which each sex and age class was equally observable. Fawns were always less observable than does during July, August, and September, the only period when they were easily differentiated from older deer. Bucks and does were usually seen at the same rate in August and November. Lincoln Index estimates were most accurate in November when all sex and age classes were most nearly equal in observability. Unequal observability was believed caused by differences in feeding and bedding time, not by group size or use of cover.