The impact of health and disease on wildlife population dynamics and individual survival is complex and poorly understood, especially in cryptic species such as chelonians. Eastern box turtles (Terrapene carolina carolina) are declining due to anthropogenic and natural factors, including disease, though the relative importance of these factors for individual survival is unknown. Determining survival rates in free-ranging chelonians is challenging because individuals are difficult to locate and recapture, deceased turtles can be quickly scavenged, and turtles can die underground during a brumation period. The purpose of this study was to estimate the apparent survival rate for wild eastern box turtles detected with common box turtle pathogens, including Terrapene herpesvirus 1, Terrapene adenovirus, and box turtle Mycoplasmopsis sp., using Cormack-Jolly-Seber models. We used mark-recapture data from 778 individuals from five box turtle populations collected over 7 yr (2016-22), paired with concurrently collected demographic and quantitative PCR pathogen detection data. Apparent survival estimates were different among the five sites, ranging from 71% to 88%, but similar between sexes. We found that pathogens modeled as a function of survival had a positive effect; turtles detected with a pathogen were two to six times more likely to survive than those without detected pathogens. However, this may be an artifact of high, unbiased pathogen prevalence paired with a relatively low probability of pathogen detection via intermittent testing. This analysis provides important estimates of apparent survival for the declining eastern box turtle and valuable information on the interaction between pathogen detection and estimates of individual survival, which can be used to better understand the drivers of population persistence in this species.
Daleo et al. (Thu,) studied this question.