Status of a Glyptemys insculpta (Wood Turtle) Population in Northeastern Minnesota

摘要

Wood Turtles (Glyptemys insculpta) have experienced population declines across their North American range and are state-listed as threatened in Minnesota, USA. To improve our understanding of the current conservation status of one population in northeastern Minnesota, we: (1) performed a snapshot comparison of population structure and relative abundance in 1990 and 2015 using survey data at 12 sites; (2) estimated the population growth rate (λ) from 1997–2014 based on population monitoring data at six sites; (3) estimated change in abundance between 2016 and 2017 based on population monitoring data at eight sites; and (4) performed a population reconstruction to estimate the minimum Glyptemys insculpta alive each year and geometric mean of λ from 1990 to 2017. The snapshot comparison indicated that relative abundance, adult sex ratio, and juvenile:adult ratio did not significantly differ between years. Captures/hour was higher in 1990 than in 2015. Mean λ from six sites monitored from 1997–2014 was 1.016, indicating the population was stable over that period. However, abundance estimates from surveys at eight sites in 2016 and 2017 indicated a substantial decrease from 247 to 112 individuals. The population reconstruction estimated a mean λ of 1.007 and 0.970 from 1990–2005 and 2006–2017, respectively. In northeastern Minnesota, Glyptemys insculpta exists in a forested landscape with predominantly public ownership and little development pressure, likely avoiding many anthropogenic stressors. However, we obtained equivocal results for our population status assessment. Continued monitoring is necessary to understand the trajectory of this Glyptemys insculpta population.