The plains harvest mouse has a thin record in Colorado. Open occurrence databases hold 341 records for it, of which just 1 is an iNaturalist photo. Almost everything known about the mouse here comes from museum specimens and trapping surveys, not from anyone spotting one in the field.
A range-edge mouse
Colorado sits near the northwestern corner of this mouse’s world. Its true stronghold is the southern Great Plains, and the state catches only the fringe of that range. Reports cluster on the northeastern prairie, especially in Weld County, and continue south and east through scattered grasslands. This is a grassland animal, so Colorado’s mountains and Western Slope lie outside its habitat.
One of the smallest rodents on the plains
The plains harvest mouse is tiny, among the lightest rodents in North America, with a woven ball of a grass nest and a diet built mostly of seeds and green shoots. Being that small and that secretive, it is almost never seen alive; it feeds under cover of darkness and stays down in the grass. The sparse record is therefore a reflection of how hard the animal is to detect, not of any real rarity across its prairie haunts.
Status and where to look
Colorado ranks the species S4 (apparently secure), and the IUCN lists it as least concern. The Comanche and Pawnee National Grasslands and the prairie margins of Barr Lake State Park sit inside its range, but this is a mouse you learn about from live-trap data rather than one you go out to watch.
Full species profile
