The impact of live-trapping on the stress response of the meadow vole (Microtus pennsylvanicus).

In physiological research on natural populations, it is essential to understand the impact of capture-induced stress because of its numerous effects on many physiological processes. Our objective was to determine the extent to which the stress levels of meadow voles (Microtus pennsylvanicus) were affected by short-term responses to live-trapping and how these were influenced by the amount of time spent in live-traps. Baseline levels were obtained from a snap-trapped sample and stress levels were determined from voles that had spent variable amounts of time in live-traps (up to 16.5 h). Stress levels were inferred from corticosterone and glucose concentrations and hematocrit levels. In the live-trapped sample, corticosterone concentrations reflect only the stress of trap confinement whereas glucose concentrations and hematocrit reflect both the effects of trap confinement and handling. Live-trapping caused corticosterone concentrations to increase by 108% (from 390.3 ng/mL to 810.6 ng/mL), glucose concentrations to increase by 58% (from 55.4 mg/dL to 87.4 mg/dL), and hematocrit levels to increase by 10% (from 49% to 54%) from baseline levels. The length of time a vole spent in a live-trap did not affect corticosterone and glucose concentrations; however, hematocrit levels increased slightly over time (0.21%/h). We conclude that live-trapping induced a stress response in voles, but that longer times in traps did not increase the stress levels