Blood sample collected from a small mammal during small mammal sampling (NEON sample class: mam_pertrapnight_in.bloodSampleID). The goal of the NEON small mammal sampling is to document the diversity, population sizes, and pathogen prevalence of small mammals through time. These parameters are assessed through a mark-recapture live trapping study (using Sherman live traps) and associated tissue collection. Each pathogen grid at terrestrial sites is trapped for 3 consecutive nights within a sampling period, while the remaining grids (i.e., diversity grids) are sampled for only one night within a sampling period. Sampling occurs year-round at a monthly (at core sites only) or approximately every other month frequency (at relocatable sites), if resources are available and winter weather conditions permit. 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 TOS Protocol and Procedure: Small Mammal Sampling (https://data.neonscience.org/documents) for more information about this sample class. NEON datasets (https://data.neonscience.org/home) associated with this sample class include Small Mammal Box Trapping and Small Mammal Sequences DNA Barcode.