Data set contains seasonal summaries (spring, summer and fall) of the number of individuals of each species of small mammal caught (relative density) on each grassland census line. Each record contains trapline, year of last fire and number of individuals per species. These live trap records are based on daily captures during three 4-day trapping peroids, March, July and October, for each of 20 permanent census lines established on 10 fire-grazing treatments (2 lines per treatment).