Hunting and environmental influences on survival of male wild turkeys in Virginia and West Virginia

Knowledge of the effects of hunting and environmental influences on survival of eastern wild turkeys (Meleagris gallopavo silvestris) is critical to managers setting fall and spring hunting seasons. Research has shown improper season frameworks can result in unsustainably high harvest rates of adult males, affect male age structure, and result in lower hunter satisfaction. Our objectives were to estimate survival rates of males, identify causes of mortality, and relate hunting and environmental influences to male turkey survival. We captured and radio-tagged male wild turkeys in Virginia (n = 204) and West Virginia (n = 197), USA, during 2004-2007. We used staggered entry Kaplan-Meier models to estimate survival and Cox Proportional Hazards Models to estimate effects of predictor variables on survival. Survival was estimated for 3 distinct periods of interest: annual, fall hunting (October-January), and spring hunting (April-May). The leading causes of mortalities (209 turkeys) were legal spring harvest (42%), predation (25%), and poaching (17%). Only 8 turkeys (4%) were taken during fall hunting seasons. Confidence intervals for annual survival of 2 year-old and 3+ year-old turkeys overlapped; therefore, we combined adult ages into a single category (2+). Adult (2+) annual survival was 0.63 (95% CI = 0.58-0.69) and the harvest rate was 25% (95% CI = 20-29%) for the combined states. Annual survival rates for adults (2+) were greater than in most other published studies, whereas adult (2+) spring harvest rates were lower. For juvenile males, annual survival was 0.74 (95% CI = 0.68-0.79) and spring harvest rate was 7% (95% CI = 3-11%). High juvenile and adult (2+) survival may have been related to low harvest rates. Adult turkeys (2+) had 46% greater risk of dying than one-year-old birds and were 3.7 times more likely to be harvested than juveniles. Age, a relative phenology index (RPI; spring green-up), and white oak (Quercus alba) acorn production were included in the top models for annual survival, spring season survival, and spring harvest risk. Increasing RPI (more foliage) decreased mortality risk and greater white oak (Quercus alba) acorn abundance increased mortality risk. Across 4 regions in the 2 states, fall survival was high (0.90, 95% CI = 0.87-0.93). The impact of fall hunting on males in Virginia was low (5% harvest rate, 95% CI = 0-9%). Overall, spring harvest had the greatest effect on male survival, although those effects were moderated by the previous fall white oak crop and the onset of green-up in the spring.