Harper, E.K., D.E. Welberg Canfield, and D.M Bruns Stockrahm. 1994. Ecology of the northern grasshopper mouse (Onychomys leucogaster) in western Minnesota. Final report submitted to the Minnesota Department of Natural Resources. 73 pp.
During the summer of 1993, 6 study sites in Clay County, Minnesota, were live-trapped in order to determine the distribution of populations of the northern grasshopper mouse (Onychomys leucogaster). Sites were generally examined for the presence of northern grasshopper mice using a preliminary trap-line of 25 traps placed 10 m apart. Traps were pre-baited for two nights and set on the third and fourth nights. Traps were checked for two consecutive mornings. If preliminary trapping resulted in the capture of a northern grasshopper mouse, the area was intensively trapped using a 7 x 7 trap grid with traps 10 m apart. This grid was centered around the location of the northern grasshopper mouse capture(s). Traps were pre-baited for two nights, and set on the third through the sixth nights. Traps were checked for 4 consecutive mornings. A total of 9 northern grasshopper mice were captured: 5 males and 2 females at a commercial gravel pit (Site 1: T141N, R46W, NE 1/4 of S36) and 1 male and 1 female at Bluestem Prairie (Site 4: T139N, R46W, W1/2 of S23). A northern grasshopper mouse was believed to have been sighted at Bicentennial Prairie (Site 2: T141N, R45W, SW 1/4 of S5), but none were captured at this site. All northern grasshopper mice in this study were associated with sandy or gravelly soils and sparse vegetation. Although all males were fully or partially scrotal and all females appeared pregnant or perforate, no juveniles were captured. Nontarget species captured included 72 deer mice (Peromyscus maniculatus), 1 white-footed mouse (Peromyscus leucopus), 24 meadow voles (Microtus pennsylvanicus), and 9 prairie voles (Microtus ochrogaster). Presently, the biggest threat to northern grasshopper mice in western Minnesota appears to be habitat destruction due to sand/gravel excavation. Northern grasshopper mouse numbers appeared low in Clay County, MN, and it is recommended that the northern grasshopper mouse be considered for inclusion in Minnesota's "List of Special Concern Species" which currently includes the prairie vole.