Survival of Unexploited Bobcats in Southern Illinois

Knowledge of survival rates is integral to understanding factors influencing population dynamics. Although bobcat (Lynx rufus) survival has been quantified throughout most of its range, few studies exist of unexploited populations and of populations in areas of high road and human density. Therefore, we estimated annual and seasonal survival rates and cause-specific mortality for 75 bobcats (39 F, 36 M) in southern Illinois during 1995-2000. Annual survival rates (M = 0.823, F = 0.857) were similar between sexes (P = 0.580). Seasonal survival rates ranged from 0.869 to 0.948 and were similar among seasons and sexes (P= 0.412). Pooled estimates of annual and seasonal survival ranged from 0.839 to 0.938 and were among the highest reported for bobcats. When seasonal mortality agents occurred for both sexes, rates of seasonal cause-specific mortality ranged from 0.016 to 0.081 and did not differ between sexes (P≥0.317). Most mortalities were human-caused, and vehicle-caused mortality rates were the highest reported for bobcats. Although current human influence is not severely limiting bobcat populations in southern Illinois, we predict that continued human expansion into rural areas may adversely affect bobcats.