Variation in Brood Sex Ratios of Texas Rio Grande Wild Turkeys

Authors:
  • BCBret A. Collier
    Bret A. Collier
  • KMKyle B. Melton
    Kyle B. Melton
  • JDJustin Z. Dreibelbis
    Justin Z. Dreibelbis
  • WKWilliam P. Kuvlesky
    William P. Kuvlesky
  • GPGlenn A. Proudfoot
    Glenn A. Proudfoot
  • RARay Aguirre
    Ray Aguirre
  • DHDavid G. Hewitt
    David G. Hewitt
  • TST. W. Schwertner
    T. W. Schwertner
  • SDStephen J. Demaso
    Stephen J. Demaso
  • NSNova J. Silvy
    Nova J. Silvy
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Abstract
We evaluated brood sex ratio (BSR) variation in Rio Grande wild turkeys (RGWT; Meleagris gallopavo intermedia ) in the Edwards Plateau and South Texas Plains of Texas, USA, during 2005‐2006. Offspring sex was determined from DNA extracted from tissue biopsies of embryos from unhatched eggs or vascular tissue from eggshells of hatched and depredated eggs. Sex ratio across all eggs was 56.3% male (135/240; X 2 1 = 3.75, P = 0.053). We found that mean population growth rate based on a population simulation with BSR at unity averaged 1.02 (range = 0.924‐1.058), whereas it declined to 0.978 (range = 0.816‐1.037) using BSR estimates from our study. Although our statistical analyses did not detect BSRs different from unity in BSR, our simulation modeling demonstrated that BSR variation caused biologically significant differences in mean population growth rates. Even though the biological mechanism controlling primary sex ratio remains unknown, our estimates of BSR should allow managers to more reliably predict population dynamics insuring viable RGWT populations across Texas.

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