Factors influencing eastern wild turkey population growth in northeastern South Dakota
Data files
Jan 19, 2026 version files 555.04 KB
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LambdaSimulation.R
5.24 KB
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ParamsSimulation.R
3.16 KB
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PopModel.R
4.93 KB
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PublishedParams.csv
300 B
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README.md
3.46 KB
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SimulatedParams.csv
537.94 KB
Abstract
Eastern wild turkeys (Meleagris gallopavo silvestris) in northeastern South Dakota appeared to be expanding soon after reintroduction in the 1990s; however, recent hunter success trends suggest a population decline in this region. While the cause of the apparent decline was unclear, out of an abundance of caution, managers closed the fall either-sex hunting season throughout much of the region in 2014. An investigation into the factors driving population growth within this system is needed to determine the most effective management strategies for increasing abundance. We incorporated age-class-specific estimates of female survival and lower-level reproductive parameters into a female-only, 2-stage pre-breeding birth-pulse model to project the population growth rate. Additionally, we performed perturbation analyses and conducted a life-stage simulation analysis (LSA) to assess the impact of each demographic parameter on population growth. The finite rate of change indicates this population was declining-to-stable (λ = 0.808; 95% CI = 0.602, 1.010), and population growth was most greatly affected by changes in female survival. Management activities should focus on improving female survival by reducing the top two sources of mortality within this system—mammalian predation and haying equipment. Improved availability of quality nesting habitats could reduce female risk of predation and result in fewer females nesting in alfalfa hayfields, where nest failure is certain, and females are at risk of mortality due to haying. Improving female survival in northeastern South Dakota should increase the abundance of wild turkeys and improve hunting opportunities in the region.
https://doi.org/10.5061/dryad.6t1g1jx82
Description of the data and file structure
We obtained published means and 95% confidence intervals of vital rates for female eastern wild turkeys in northeastern South Dakota from Tyl et al. 2020 and Tyl et al. 2023. We simulated 3,000 values of each vital rate from these published estimates and import these into a 2-stage matrix projection model to summarize the age-structured variation in demographic rates for female turkeys in northeastern South Dakota. We estimated the finite rate of population change for each model iteration and conducted perturbation analyses (i.e., elasticity analysis, LSA) to determine which vital rates had the greatest impact on population growth.
Files and variables
File: PublishedParams.csv
Description: published age-class specific vital rates (i.e., annual survival, reproductive parameters) from Tyl et al. 2020 and Tyl et al. 2023.
Variables
- var: list of vital rates
- p_mean: mean vital rate estimates for each ‘var’ published in Tyl et al. 2020 or Tyl et al. 2023
- p_upp: p_upp: upper 95% confidence interval value for each ‘var’ published in Tyl et al. 2020 or Tyl et al. 2023
- p_low: lower 95% confidence interval value for each ‘var’ published in Tyl et al. 2020 or Tyl et al. 2023
File: SimulatedParams.csv
Description: 3,000 values of simulated vital rates.
Variables
- sa: 3,000 simulated values of adult annual survival
- sy: 3,000 simulated values of yearling annual survival
- nra: 3,000 simulated values of adult nesting rate
- nry: 3,000 simulated values of yearling nesting rate
- nsa: 3,000 simulated values of adult nest survival rate
- nsy: 3,000 simulated values of yearling nest survival rate
- rna: 3,000 simulated values of adult re-nesting rate
- rny: 3,000 simulated values of yearling re-nesting rate
- haa: 3,000 simulated values of adult hatchability
- hay: 3,000 simulated values of yearling hatchability
- psa: 3,000 simulated values of adult poult survival
- psy: 3,000 simulated values of yearling poult survival
- sj: 3,000 simulated values of juvenile female survival over a 242-day period
- csa: 3,000 simulated values of adult clutch size
- csy: 3,000 simulated values of yearling clutch size
File: ParamsSimulation.R
Description: R code used to simulate 3,000 values of vital rates based on means and 95% confidence intervals of demographic rates reported in Tyl et al. 2020 and Tyl et al. 2023.
File: PopModel.R
Description: R code used to conduct the matrix projection model, perturbation analysis, and life-stage simulation analysis.
File: LambdaSimulation.R
Description: R code used to simulate variation in λ across the range of possible values for each lower-level vital rate.
Code/software
We used the POPBIO package version 2.8 in Program R version 4.2.1.
Access information
Data was derived from the following sources:
- Tyl, R. M., C. T. Rota, and C. P. Lehman. 2020. Factors influencing productivity of eastern wild turkeys in northeastern South Dakota. Ecology and Evolution 10:8838–8854.
- Tyl, R. M., C. T. Rota, and C. P. Lehman. 2023. Factors influencing survival of female eastern wild turkeys in northeastern South Dakota. Wildlife Society Bulletin 47:e1429.