50 years of spring wild turkey harvest in Indiana, 1970–2019

Abstract

AbstractFifty years (1970–2019) of spring hunting of eastern wild turkeys (Meleagris gallopavo silvestris) has occurred in Indiana, spanning turkey population restoration in the state. A conservative spring harvest structure of a single bird bag, relatively short seasons with a late April opening date was in place for all spring seasons. Herein, we examined trends in state‐wide harvest parameters over time and modeled annual harvest at the county level to examine drivers of harvest. Statewide, harvests, hunter numbers, success rates, and effort initially increased as restoration progressed, with increases in areas open to hunting and days of hunting opportunity. Spring harvests peaked during 2006–2010 and declined 4.7% during 2015–2019. Hunter success peaked during 1998–2002 at 27 ± 0.7% (mean ± SE), then declined to 21 ± 0.6% during 2015–2019. After 1993, spring trips/hunter began to level off with 5 ± 0.46 trips/hunter during 2015–2019. The subadult portion of harvest grew during 1970–1974, stabilized at 30 ± 2.0% during 1976–95, and then declined to 17 ± 1.4% during 2015–2019. Two‐year old males comprised 49% ± 1.5% of the harvest during 1985–2009, then shifted during 2015–2019 to 41 ± 1.5% 2‐yr‐olds and 42 ± 2.8% males ≥3 yr of age. The conservative spring season structures maintained through the restoration era with restricted county fall seasons (1 bird bag either sex, 12‐day firearm initiated post‐restoration in 2005) likely buffered spring harvests from declining production in recent years. We used a 2‐step approach to model annual harvest at the county level. First, we fit a piecewise temporal model with 2 breakpoints to capture the underlying growth of post‐restoration harvest, and its changing slope over time. Second, we added explanatory covariates to the model to explore potential mechanisms for differences in harvest across space and time. Using a generalized linear mixed model, we included variables related to harvest age structure, landscape composition, and restoration effect. Harvests leveled off over time with the best harvest model showing geometric growth for the first 16 years of harvest, followed with moderate growth for 17–39 years of harvest, before leveling off after 40 years under a conservative season structure. The primary model drivers of annual harvest were the proportion of 2‐yr‐olds in the harvest, followed by the number of years between stocking and harvest and the number of turkeys released on the landscape, landscape edge density, and forest clumpiness. Our model results emphasized the importance of production, supported turkey restoration techniques, and demonstrated the suitability of landscapes with diverse land cover types. Ultimately, the availability of quality brood cover along with climatic shifts toward increased precipitation, will influence production trends critical to sustaining current turkey population levels. These changes will in turn, influence the level of 2‐yr‐old males in subsequent spring harvests, hunter success, and the future of the open‐permit structure, depending on the level of hunter demand.