Digit Preference in Reported Harvest Among Illinois Waterfowl Hunters

Abstract

Digit preference is a form of response error whereby individuals report behaviors such as days of participation in numbers ending in zero or five. Keeping seasonal records may decrease digit preference and provide more accurate records of recreationists' behaviors. This study tested the effect of providing a preseason harvest card for recording harvest during the season in reducing digit preference among waterfowl hunters in Illinois. Reported mallard duck ( Anas platyrhyncus ) harvests were tested for individual digit preference (IDP) and aggregate digit preference (ADP). Individual digit preference among the harvest card group approximated the expected probability (22%), whereas the group with no harvest card exhibited IDP of 31%, which is a significant difference. Aggregate digit preference was 9% for the harvest card group and 18% for the group without harvest cards. Given the level of digit preference, it may have an impact on wildlife harvest estimates based on self-reported counts provided via mail surveys. This study supports previous work that suggests record-keeping on the part of recreation participants provides a means to decrease harvest estimate digit preference.