This collection contains small mammals collected as bycatch during ground beetle sampling (NEON sample class: bet_sorting_in.subsampleID, mam,bet_archivepooling_in.subsampleID.mam). Ground beetles are sampled using pitfall traps (16 oz deli containers filled with 150 or 250 mL of propylene glycol). Four (pre-2018) or 3 (2018 and beyond) traps are deployed in each of 10 (pre-2023) or 6 (2023 and beyond) plots at each terrestrial NEON site, with traps arrayed approximately 20 meters from the center of the plot. Sampling occurs biweekly throughout the growing season (when temperatures are above 4 degrees C). Vertebrate bycatch is stored in 95% ethanol and archived in a temperature (17-18°C) and humidity controlled environment. See related links below for protocols and NEON related data products.