Increased Mortality in Wood Turtles (Glyptemys insculpta) During Drought Years

Matthew D. Kamm^1,*, Cara L. McElroy¹, Bryan Windmiller¹, Emilie R. Wilder¹, James F. Welch¹, and Julie Lisk¹

¹Zoo New England, Boston, MA 02121. *Corresponding author.

Northeastern Naturalist, Volume 31, Special Issue 12 (2024): G47–G56

First published early online: 9 June 2024

Abstract
Increased mortality of freshwater turtles due to changing climate conditions, possibly due to increased predation because of a lack of refugia in drought years, is a key issue facing turtle-recovery efforts. Zoo New England’s Field Conservation department has been studying and protecting Glyptemys insculpta (Wood Turtle) in Massachusetts since 2012 and has been headstarting juvenile turtles and tracking adult and headstart survival intensively since 2019. Following several anecdotal observations that Wood Turtle mortality was disproportionately high during drought years across several study sites, we analyzed data from a multi-year survey of 112 unique individual Wood Turtles living in eastern Massachusetts. We found via one-way ANOVA that lower mean stream depth was a significant predictor of Wood Turtle mortality (P = 0.037) and that a generalized linear model using stream depth as a predictor of Wood Turtle survival had more explanatory power than models using rainfall, temperature, or Julian date. We believe that most of the mortality was due to increased mammalian predation when access to safe aquatic habitats for resting and sheltering from predators is reduced due to lower-than-average streamflown.

Download Full-text pdf (Accessible only to subscribers. To subscribe click here.)