This collection contains blood samples collected from small mammals during small mammal sampling (NEON sample class: mam_pertrapnight_in.bloodSampleID). Small mammal sampling is based on the lunar calendar, with timing of sampling constrained to occur within 10 days before or after the new moon. Typically, core sites are sampled 6 times per year, and relocatable sites 4 times per year. Small mammals are sampled using box traps (models LFA, XLK, H.B. Sherman Traps, Inc., Tallahassee, FL, USA). Box traps are arrayed in three to eight (depending on the size of the site) 10 x 10 grids with 10m spacing between traps at all sites. Small mammal trapping bouts are comprised of one or three nights of trapping, depending on whether a grid is designated for pathogen sample collection (3 nights) or not (1 night). Blood is collected using the mandibular blood sampling technique, which involves collection from the submandibular and/or facial vein or artery. Only blood samples with volumes of at least 20 microliters are sent for pathogen analysis. The remaining samples are archived in the NEON Biorepository at -80 degrees Celsius. Blood samples are collected at a frequency of once per individual per bout. See related links below for protocols and NEON related data products.