Maturation and reproduction in headstarted Blanding's turtles

Post-release monitoring is key to ensuring that conservation interventions like reintroduction, reinforcement, and headstarting are effective. However, for long-lived species, monitoring over sufficiently long time periods to confirm successful maturation and reproduction can be challenging. We use long-term monitoring data to document post-release maturation and reproduction by headstarted Blanding's turtles Emydoidea blandingii, a long-lived late-maturing species threatened by habitat loss and degradation, road mortality, and increased predation. We found that among headstarted Blanding's turtles, adult mass was attained in as little as 7 years, 3 years earlier than among non-headstarted turtles. We documented successful reproduction by 29 headstarted females and courtship by 2 headstarted males, the youngest of which were each 10 years old. In comparison, the youngest reproductive non-headstarted female and courting male were 11 and 12 years old, respectively. We found no difference in clutch size or reproductive frequency between headstarted and non-headstarted females (mean clutch size = 12.5 vs. 13.5; reproductive frequency = 0.964 vs. 0.943). Hatch success differed between headstarted and non-headstarted females depending on whether clutches were obtained by hormonal induction in enclosures (headstarts: 0.52; non-headstarts: 0.83), by hormonal induction in the field (headstarts: 0.73; non-headstarts: 0.74), or in maternity pens without hormonal induction (headstarts: 0.80; non-headstarts: 0.98). We found no effect of female age on clutch size, hatch success, or reproductive frequency. Our results add to a growing body of evidence for the success of headstarting as a conservation intervention.