Work

Archival data reveals human impacts on Blanding’s turtle population persistence

Year: 2025

Type: article

Abstract: Adult survival and nest success figure prominently in turtle population dynamics but human impacts on these life stages can be difficult to quantify. We integrated pooled sets of monitoring and telemetry data to quantify human impacts on adult survival for the imperiled Blanding’s turtle, Emydoidea blandingii. We then used population viability analyses to test the sensitivity of extinction risk for scenarios differing in the degree of human impacts and initial adult population size. We also extracted information on Blanding’s turtle nest sites, quantifying the frequency of nests in human-modified habitats. Motor vehicles, machinery, and railways accounted for the largest number of human-caused deaths and traumatic injuries. Survival analysis of 1,541 turtle-years of telemetry data indicated that human-caused deaths have raised annual adult mortality from 4.3% to 5.2%, a 21% increase over mortality from other causes. This increase was sufficient to trigger population decline and made populations smaller than about 30 adults vulnerable to extinction. In scenarios in which juveniles also suffered human-caused mortality, even populations with 100 adults were vulnerable to extinction. More than half of the nest locations we compiled occurred in rail rights-of-way, landscaped areas, and agricultural fields, habitats that expose nesting females, nests, and hatchlings to elevated risk of injury and death. Increased preserve size, installation of road and rail barrier and passage systems, and habitat enhancements aimed at reducing the use of ‘at-risk’ nest sites would improve Blanding’s turtle population persistence.

Source: Journal for Nature Conservation

DOI: 10.1016/j.jnc.2025.126966