Not all management is equal: a comparison of methods to increase wood turtle population viability

Abstract

AbstractManagement generally targets the most tractable life stage to rescue declining populations; however, that stage may not have the largest influence on recovery. Freshwater turtles are declining globally and early stages are frequently targeted for management, although the effectiveness of these actions on population growth are relatively unknown because of incomplete demographic data. We estimated the hatchling yearly survival rate for a freshwater turtle in the field using in situ enclosures to collect missing demographic information. We used these data to develop demographic models to calculate growth rate for a hypothetical, declining population of wood turtles (Glyptemys insculpta) in Wisconsin, USA, 2014–2019. We modeled growth for populations across a range of scenarios from no management to combinations of nest protection and head‐starting at varying levels of effort. Nest protection alone did not increase population growth rate, while head‐starting alone increased population growth by 0.07, with the largest increase in growth rate, 0.11, resulting from combinations of both approaches. No combination of nest protection and head‐starting, without an increase in adult survival rate from the observed 0.88 to ≥0.95, led to population stabilization or increase. Populations of freshwater turtles, like the wood turtle, will likely only recover with a multi‐faceted approach that targets multiple life stages simultaneously.