Schwertner, Thomas Wayne (2003-05). A simulation model of Rio Grande wild turkey dynamics in the Edwards Plateau of Texas. Doctoral Dissertation. Thesis uri icon

abstract

  • I investigated the effect of precipitation and predator abundance on Rio Grande wild turkey (Meleagris gallopavo; RGWT) in Texas. My results suggested that RGWT production was strongly correlated with cumulative winter precipitation over the range of the RGWT in Texas. However, I found no evidence that predator abundance influenced RGWT production, although spatial-asynchrony of predator populations at multiple spatial scales might have masked broad-scale effects. Using the results of these analyses, as well as empirical data derived from the literature and from field studies in the southern Edwards Plateau, I developed a stochastic, density-dependent, sex- and agespecific simulation model of wild turkey population dynamics. I used the model to evaluate the effect of alternative harvest management strategies on turkey populations. Sensitivity analysis of the model suggested that shape of the density-dependence relationship, clutch size, hatchability, juvenile sex ratio, poult survival, juvenile survival, and nonbreeding hen mortality most strongly influenced model outcome. Of these, density-dependence, sex ratio, and juvenile survival were least understood and merit further research. My evaluation of fall hen harvest suggested that current rates do not pose a threat to turkey populations. Moreover, it appears that hen harvest can be extended to other portions of the RGWT range without reducing turkey abundance, assuming that population dynamics and harvest rates are similar to those in the current fall harvest zone. Finally, simulation of alternative hen harvest rates suggested that rates ≥5% of the fall hen population resulted in significant declines in the simulated population after 25 years, and rates ≥15% resulted in significant risk of extinction to the simulated population.
  • I investigated the effect of precipitation and predator abundance on Rio Grande wild
    turkey (Meleagris gallopavo; RGWT) in Texas. My results suggested that RGWT
    production was strongly correlated with cumulative winter precipitation over the range
    of the RGWT in Texas. However, I found no evidence that predator abundance
    influenced RGWT production, although spatial-asynchrony of predator populations at
    multiple spatial scales might have masked broad-scale effects. Using the results of these
    analyses, as well as empirical data derived from the literature and from field studies in
    the southern Edwards Plateau, I developed a stochastic, density-dependent, sex- and agespecific
    simulation model of wild turkey population dynamics. I used the model to
    evaluate the effect of alternative harvest management strategies on turkey populations.
    Sensitivity analysis of the model suggested that shape of the density-dependence
    relationship, clutch size, hatchability, juvenile sex ratio, poult survival, juvenile survival,
    and nonbreeding hen mortality most strongly influenced model outcome. Of these,
    density-dependence, sex ratio, and juvenile survival were least understood and merit
    further research. My evaluation of fall hen harvest suggested that current rates do not pose a threat to turkey populations. Moreover, it appears that hen harvest can be
    extended to other portions of the RGWT range without reducing turkey abundance,
    assuming that population dynamics and harvest rates are similar to those in the current
    fall harvest zone. Finally, simulation of alternative hen harvest rates suggested that rates
    ≥5% of the fall hen population resulted in significant declines in the simulated
    population after 25 years, and rates ≥15% resulted in significant risk of extinction to the
    simulated population.

publication date

  • May 2003