Demography and Viability of a Central Maine Population of Wood Turtles (Glyptemys insculpta)

Abstract

The wood turtle (Glyptemys insculpta) is experiencing widespread declines throughout its range in the eastern United States and Canada. Maine has been considered a stronghold for the species due to an abundance of suitable upland and stream habitat. Furthermore, recent studies have identified Maine as a potentially important climate refuge for wood turtles. Using data collected in a 5-yr capture-mark-recapture study on a wood turtle population in central Maine, we estimate population size, apparent survival rates, population growth rates, and population viability. We also performed a sensitivity analysis to illustrate the impacts of slight perturbations to demographic rates. Our estimated total population size is 73 (95% CI = 69-85) individuals. Annual apparent survival varied across years, ranging from 80.5% to 97.5%, with females having a slightly higher survival at 94.9% (95% CI = 81.6%-97.8%) than males at 92.8% (95% CI = 77.6%-97.4%). The baseline population viability analysis model predicted a k of 0.93 (95% CI = 0.91-0.95) and a 100% probability of extinction within 150 yrs. Despite some broad permutations in our baseline demographic parameters, there were no scenarios included within our sensitivity analysis that increased the population's growth rate to a positive value. These results have implications for the long-term persistence of wood turtles in Maine and throughout their range. Our study helps fill a need for current data from this area that may be used to inform both local and regional management plans. KEY WORDS. -capture-mark-recapture, Program MARK, population viability analysis, VORTEX