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 3 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.