Data was collected in the laboratory using field-collected salamanders (Plethodon cinereus) from 4 study sites in ME, NY, MD, and VA. The file was created using Microsoft Excel. The column headings are as follows: experiment (indicates which of the physiological studies the data corresponds to); site code (indicates the state of origin); site name (specifies the collection site); site heat value (refers to the mean daily maximum temperature at the collection site as explained in the associated manuscript); salamander ID (a unique code given to each study animal); experimental temp (15 or 25°C as explained in the associated manuscript); sex (m or f); svl (snout-vent length measured to posterior edge of cloaca); tail length (measured from posterior edge of cloaca); total length (svl + tail length); mass (refers to the mass recorded at the time of corticosterone sampling); corticosterone release rate (see associated manuscript for methodology); performance initial mass (refers to the mass recorded at the start of each thermal performance trial); performance final mass (refers to the mass at the end of each performance trial); days between mass (refers to the number of days that passed between initial and final mass events); performance (% change in mass/day); ingestion (total number of flies consumed/day during performance trial).