North American deermouse is South Dakota’s most habitat-flexible small rodent, and its 99 logged records along Lake Oahe, Lake Sharpe, and the Missouri National Recreational River are among the strongest showings for any mouse-sized mammal in the state. NatureServe ranks it S5, Secure, statewide.
Records climb sharply through summer and peak at 45 in August, tracking the season when multiple litters born earlier in the year reach trapping-detectable size. The river-bottom habitat here suits a species equally comfortable in grassland, woodland, and disturbed ground.




