Female biased offspring sex ratios of eastern wild turkeys across the southeastern United States

Prevailing theory suggests that sex ratios of offspring at birth should not differ from parity if costs of producing offspring of both sexes are similar. However, offspring sex ratios may deviate from parity when there is sex specific variation in fitness returns. We assessed offspring sex ratios of eastern wild turkeys (Meleagris gallopavo silvestris) across the southeastern United States by molecular determination of sex from eggshell membranes of hatched clutches. Our objective was to evaluate whether offspring sex ratios differed from parity and to examine potential drivers of variation in offspring sex ratios across and within our study sites. We sexed 724 offspring from 83 nests using molecular markers and identified 278 males and 446 females, with a sex ratio of 38% male. We found that offspring sex ratios were biased towards females on three hunted study sites but did not differ from parity at our remaining non-hunted site. Specifically, on sites with spring hunting, where male mortality was increased due to harvest, the probability of producing male offspring was 47% lower than on our non-hunted site. Our findings suggest that female wild turkeys may adaptively adjust the sex ratio of their offspring based on predictable, sex specific mortality, favoring the sex with higher survival, thereby enhancing their lifetime fitness. Our results provide insights into reproductive strategies of wild turkeys and the influence of hunting on sex ratios in Galliform offspring.