Faculty Publications


A regional analysis of Glyptemys insculpta (Wood turtle) survival in the Upper Midwest of the USA

Document Type



Adult, Iowa, Midwest, Minnesota, Modeling, Population, Predation, Wisconsin

Journal/Book/Conference Title

Herpetological Conservation and Biology





First Page


Last Page



The Wood Turtle (Glyptemys insculpta) is a species of conservation concern in the Upper Midwest of the USA. State agencies and partners in the region are working collaboratively to identify threats to G. insculpta populations and to implement effective management actions. One component of this conservation initiative is to improve our understanding of the impacts of different management strategies on long-term viability of populations. This requires estimates of population vital rates, which are currently lacking for most G. insculpta populations in the Upper Midwest and across the range of the species. In this study, we used individual-level monitoring data to estimate annual survival of adult G. insculpta in Iowa (two populations, four monitoring years, 52 individuals), Minnesota (one population, two monitoring years, 29 individuals), and Wisconsin (two populations, two monitoring years, 32 individuals). We estimated annual survival for each sex, population, and year using a known-fates analysis with a binomial model. Twenty-three (20%) of the monitored individuals died during the study. For 12 turtles for which we knew the cause, predation was responsible for most (n = 9; 75%) mortalities. Estimated annual survival of males and females ranged from 0.49–1.00 and 0.64–1.00, respectively, among populations and years. Estimated survival of all individuals was 0.86 in Iowa for 2012–2015, 0.89 in Minnesota for 2015–2016, and 0.87 in Wisconsin for 2014–2015. This study increases our understanding of adult G. insculpta survival rates and causes of mortality in the western Great Lakes portion of the range of the species and provides useful vital rate estimates for population viability analyses.

Original Publication Date



UNI ScholarWorks, Rod Library, University of Northern Iowa



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