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

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 mortalityonly occurred while a female was incubating. Reducing female mortality due to haying, by delaying cutting, installing flushing

Survival and cause‐specific mortality of male wild turkeys across the southeastern United States

“…Abundance, reproduction, and harvest, however, have concomitantly declined throughout portions of the species’ range (Byrne et al 2015, Casalena et al 2015, Chamberlain et al 2022), which prompts us to question whether our observations of adult male survival are high enough to mitigate for ongoing declines in productivity. Wild turkey population trajectories are influenced primarily by productivity and adult female survival (Roberts and Porter 1996, Londe et al 2023, Tyl et al 2023), and it is unclear how fluctuating rates of male survival influence population trajectories (Healy and Powell 1999). We also point to the significant variation in data collection and analysis present across past studies, which could be responsible for discrepancies in published vital rates and trends.…”

Factors influencing population growth in a bobcat population

“…We assumed male and female kitten and juvenile survival were the same. We assumed survival of individual i during day t was a Bernoulli random variable: $$${y}_{it}\unicode{x0007E}\text{Bernoulli}({y}_{i(t-1)}{p}_{it}),$$$where y it = 1 if individual i survived day t , y it = 0 if individual i died during day t , and p it represented daily survival probability (Royle and Dorazio 2008, Lehman et al 2017, Tyl et al 2023). We assumed daily survival probability was a logit linear function of age (0–3 months [kitten], 3–12 months [juvenile], 12–24 months [yearling], and ≥24 months [adult]).…”