Evidence for Recruitment-Mediated Decline in an Eastern Box Turtle (Terrapene carolina carolina) Population Based on a 30-Year Capture–Recapture Data Set from Maryland

The eastern box turtle (Terrapene carolina carolina) population at the Jug Bay Wetlands Sanctuary, Lothian, Maryland, has been monitored continuously for 29 yr (1995–2023). We used open-population capture–recapture models (Jolly–Seber) to estimate annual population size, survival probability, and recruitment rate. The model allows for unknown sex of individuals and includes information on individuals found dead. Our analysis documented a long-term decline of approximately 67% in box turtle population size at the Sanctuary over this nearly 3-decade period. We estimated annual survival for both males and females, which does not show a systematic increase or decrease over time, averaging about 0.90 (95% CI: 0.86, 0.93) for females and 0.97 (95% CI: 0.94, 0.98) for males. Conversely, per-capita recruitment showed a marked decline over the first 15 yr of record, suggesting that population declines may be due to reduced recruitment. Conservation efforts for the species could benefit from a formal population viability analysis to understand the relative effects of survival and recruitment on changes in population size for this long-lived species.