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.
|Original language||English (US)|
|Number of pages||10|
|Journal||Herpetological Conservation and Biology|
|State||Published - Apr 2018|
Bibliographical noteFunding Information:
Acknowledgments.—This study was funded by the Minnesota Department of Natural Resources through a Competitive State Wildlife Grant (#F14AP00028), with additional financial support provided to Madaline Cochrane through a University of Minnesota Integrated Biosciences Graduate Program summer fellowship. We thank Bruce Brecke and Lynelle Hanson for field assistance in 1990. We thank Katelin Goebel, Stefan Nelson, Lucas O’Neil, Nathan Ose and Ashlee Ricci for field assistance in 2015. Kelcy Huston, Cord Reno, Alek Hol-leran, Josh Kircher and Maria Berkeland assisted with surveys in 2016 and 2017. We thank local landholders who allowed us access to conduct research on their lands. Maya Hamady was instrumental in obtaining funding for G. insculpta research in northeastern Minnesota. Sampling and handling methods were approved by the University of Minnesota Institutional Animal Care and Use Committee (Protocol No. 1504-32514A), and permitted by the Minnesota Department of Natural Resources. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
© 2018. Madaline M. Cochrane. All rights reserved.
- Relative abundance