Factors affecting conception date variation in white-tailed deer

Understanding the factors that influence timing of reproduction can be of value to wildlife managers. We used estimated breeding dates of captive individual white-tailed deer (Odocoileus virginianus) in Texas and Mississippi, USA, and wild deer populations in Mississippi, to document natural variation within individuals and populations, and to determine whether body condition, age, or moon phase explained conception date variation. Mean conception date of captive individual deer was 1 December with amedian of 26 November, a standard deviation of 13.6 days, and a mean range of 33 days. Overall mean conception date for wild populations in Mississippi was 1 January with a standard deviation of 13.4 days and a mean range of 46 days. Annual population mean conception date had a standard deviation of 4 days and a range of 12 days. Moon phase did not predict accurately conception date for individuals or populations of deer. Body condition did not influence conception date at the population level. Individual females 2.5 years old bred earlier than females 1.5 and 3.5 years old; however, the difference was minimal andmay have been influenced by the mean gestation used to determine conception date. When scheduling recreational hunting opportunities relative to population breeding dates, managers should rely on local reproductive data and should not rely on predictions based on moon schedules. Further assessment of the individual variation in conception date and potential environmental cues is warranted.