A resurvey of a Wood Turtle (Glyptemys insculpta) population in northern New Hampshire, USA, after 13 years

Populations of Wood Turtle (Glyptemys insculpta) have declined across the species’ range. We surveyed a protected Wood Turtle population in northern New Hampshire in 2007 and again in 2020 to determine whether the size of the population had changed and the average annual survival rate between the two periods. We used closed-population loglinear models to estimate the adult population size in 2007 and 2020 and, for the subset of turtles captured in both years, to estimate the rate of survival. Based on these models, we found an adult population of 56 (95% CI 33–126) in 2007 and 46 (95% CI 31–85) in 2020; we did not detect a statistically significant difference between the two population estimates. In addition, we estimated a 96% average annual adult survival rate and determined this rate could be no lower than 92%. This information provides useful baseline data and will help inform future monitoring and threat mitigation work for this population