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Factors influencing survival of female eastern wild turkeys in northeastern South Dakota

Cite this dataset

Tyl, Reina; Rota, Christopher; Lehman, Chad (2024). Factors influencing survival of female eastern wild turkeys in northeastern South Dakota [Dataset]. Dryad. https://doi.org/10.5061/dryad.wm37pvmpr

Abstract

Population growth can be sensitive to changes in survival rates for many avian species. Understanding sources of mortality, and how to mitigate negative effects on survival, can give managers insight into factors contributing to population change. Harvest trends of eastern wild turkeys (Meleagris gallopavo silvestris) in northeastern South Dakota suggest a decline in abundance. We investigated factors influencing survival of wild turkeys to identify potential factors contributing to the decline. We monitored 122 female wild turkeys using VHF radio transmitters from February 2017 to April 2019. Annual survival was 0.52 (95% CI = 0.33–0.64) for juvenile and 0.49 (95% CI = 0.23–0.63) for adult females, respectively. Daily survival probability was significantly lower during the spring (log‐odds ratio [LOR] = −0.9; 95% CI = −1.5–−0.2) and while a juvenile female was incubating (LOR = −0.67; 95% CI = −1.23–−0.09) but not while an adult female was incubating (LOR = −0.35; 95% CI = −0.92–0.24). Mammalian predation was the leading cause of mortality, and female wild turkeys were most vulnerable to predation during the spring while engaging in nesting and rearing of young broods. Wild turkeys were at risk for additional sources of mortality while incubating nests that were not contributors to mortality during other periods of the year, as deaths caused by haying equipment—the second greatest cause of mortality—only occurred while a female was incubating. Reducing female mortality due to haying, by delaying cutting, installing flushing bars on haying equipment, or increasing availability of suitable nesting cover types to reduce the probability of nesting in hayfields, could improve female survival. Annual survival during our study was about 16–29% lower than survival estimates from northeastern South Dakota during the 1990s, suggesting that reduced female survival could be contributing to the apparent decline in wild turkey abundance.

README: Factors Influencing Survival of Female Eastern Wild Turkeys in Northeastern South Dakota: Open Source Data

Metadata for The Hen (Female) Survival Analysis Prior Distribution Calculation

Files needed to calculate Hen Survival Analysis Prior Distributions:

  • beta.txt – JAGS model code for survival probability estimation
  • gaussian.txt – JAGS model code for age-class specific survival probability estimation
  • Prior_Distribution.RMD – R Markdown file used to run prior distribution calculation 
  • Prior_Estimates.xlsx – Excel Workbook (2 sheets) containing published estimates of hen annual survival from studies of turkeys in the Midwest used to calculate prior distributions for the hen survival analysis

Description of variables within “Prior_Estimates.xlsx”

  • Sheet = Combined
    • Estimate – published annual hen survival estimates where hen age was pooled
    • Source – the published study each estimate originated from
  • Sheet = Age
    • Adult – published annual survival estimates for adult hens
    • Juv – published annual survival estimates for juvenile/yearling hens
    • Source – the published study each estimate originated from

Metadata for Hen (Female) Survival Analysis

Files needed to run the Hen Survival Analysis:

  • HenObservations.csv – observation history for each hen monitored over the course of the study
  • HenSurvival_InputData.RData – R object containing all hen survival model input data
  • HenSurvivalAnalysis_DataSetUp.R – R code used to develop hen survival model input data
  • HenSurvivalModel.R – R code used to run hen survival analysis
  • hensurvmodel.txt – JAGS model code for hen survival analysis
  • IncubationData.csv – incubation history for each nest attempt
  • MilbankDailySumm2016to2019.csv – raw temperature and precipitation from NOAA NCEI CDO (Menne, M. J., I. Durre, B. Korzeniewski, S. McNeal, K. Thomas, X. Yin, S. Anthony, R. Ray, R. S. Vose, B. E. Gleason, and T. G. Houston. 2012. Global Historical Climatology Network - Daily (GHCN-Daily), Version 3.26. NOAA National Climatic Data Center. http://doi.org/10.7289/V5D21VHZ. Accessed March 5, 2020.)

To run the hen survival analysis, start by opening the “HenSurvivalModel.R” file.  Ensure the “Hen Survival” folder is set as the working directory. Ensure all required packages (i.e., jagsUI & ggplot2) are installed and loaded. Execute code.

Description of variables within “HenObservations.csv”

  • Band_ID – the identification number on leg bands of individually marked eastern wild turkey hens. A factor with 122 levels where each level is a unique identification number (and unique individual hen).
  • Age – the age of the hen at the time of capture. A factor with 2 levels: adult or juvenile (i.e., yearling).
  • Date_Captured – the date each hen was captured.   
  • Last_Obs_Date – the last date the hen was observed alive. If the hen was still alive at the end of the study period, then no date is entered into this column for that hen.
  • Date_Mortality – the date the hen was found to have died (i.e., mortality signal was detected) (if applicable).

Description of variables within “IncubationData.csv”

  • Band_ID – the identification number on leg bands of individually marked eastern wild turkey hens that reached incubation of at least one nest during at least one year of the study. A factor with 89 levels where each level is a unique identification number (and unique individual hen).
  • Incubation_Date – the start date of the incubation period (i.e., first day the hen was known to be incubating a nest).
  • Fate_Date – the day after the end of the incubation period (i.e., first day the hen was known to be no longer incubating a nest).

Description of variables within “MilbankDailySumm2016to2019.csv”

  • STATION – the station identification code. Please see http://www1.ncdc.noaa.gov/pub/data/ghcn/daily/ghcnd-stations.txt for a complete list of stations and their metadata.
  • NAME – the name of the station (usually city/airport name). Optional output field.
  • LATITUDE – decimated degrees w/ northern hemisphere values > 0
  • LONGITUDE – decimated degrees w/ western hemisphere values < 0
  • ELEVATION – elevation above mean sea level (tenths of meters)
  • DATE – the date of the record
  • PRCP – precipitation in mm
  • SNOW – snowfall in mm
  • SNWD – snow depth in mm
  • TMAX – maximum temperature in Celsius
  • TMIN – minimum temperature in Celsius
  • TOBS – temperature at time of observation in Celsius

Metadata for Winter Weather Comparison Figure creation

Files needed to create the Winter Weather Comparison figure:

  • MilbankDailySummary1990to2019.csv – raw temperature and precipitation from NOAA NCEI CDO (Menne, M. J., I. Durre, B. Korzeniewski, S. McNeal, K. Thomas, X. Yin, S. Anthony, R. Ray, R. S. Vose, B. E. Gleason, and T. G. Houston. 2012. Global Historical Climatology Network - Daily (GHCN-Daily), Version 3.26. NOAA National Climatic Data Center. http://doi.org/10.7289/V5D21VHZ. Accessed March 5, 2020.)
  • WinterWeatherCompare.png - image illustrating the total snow accumulation (cm) during the winter months (1-January to 31-March) and mean January air temperature (Celsius) recorded in Milbank, South Dakota, USA during the study years compared to 30-year normals. Included as a figure in the manuscript.
  • WinterWeatherComparison.R – R code used to create “WinterWeatherCompare.png”

Description of variables within “MilbankDailySumm2016to2019.csv”

  • STATION – the station identification code. Please see http://www1.ncdc.noaa.gov/pub/data/ghcn/daily/ghcnd-stations.txt for a complete list of stations and their metadata.
  • NAME – the name of the station (usually city/airport name). Optional output field.
  • LATITUDE – decimated degrees w/ northern hemisphere values > 0
  • LONGITUDE – decimated degrees w/ western hemisphere values < 0
  • ELEVATION – elevation above mean sea level (tenths of meters)
  • DATE – the date of the record
  • PRCP – precipitation in mm
  • SNOW – snowfall in mm
  • SNWD – snow depth in mm
  • TMAX – maximum temperature in Celsius
  • TMIN – minimum temperature in Celsius
  • TOBS – temperature at time of observation in Celsius

Funding

South Dakota Game, Fish and Parks, Award: Grant W- 75-R, Federal Aid Study 7564

National Wild Turkey Federation, Award: NWTF Project No: 2.1.2017