Influence of Natural Food Abundance on Black Bear Harvests in Minnesota

Abstract

Many agencies use data on hunter success and harvest composition to guide decisions about black bear (Ursus americanus) management, despite well-known limitations of such data. The likely influence of natural food abundance on harvests has been acknowledged, yet few studies have examined this relation. We conducted a simple survey, employing subjective ratings by experienced observers, to monitor food abundance across Minnesota's bear range, and used these data to interpret a 12-year record of hunting success and harvest composition. Percent females in the harvest, mean age of females killed, and hunting success were related inversely to fall food abundance, particularly hazelnuts (Corylus spp.) and acorns (Quercus spp.). Percent females in the harvest, mean age of females killed, and estimated harvest rates for most sex-age classes, particularly adult females, also increased with increased number of hunters. After accounting for fall food and number of hunters, the estimated size of the bear population appeared to have little effect on hunting success and harvest sex ratio; that is, bear harvest data apparently yielded little insight into population status. Despite the simple format and subjective nature of our food survey, it adequately explained most of the year-to-year variation in hunting success and the sex-age composition of the harvest.