South Dakota mammals

Western Harvest Mouse in South Dakota

Reithrodontomys megalotis

Native to South Dakota S5 Secure in South Dakota

Not listed as nonindigenous in South Dakota by USGS NAS; native to its South Dakota range.

IUCN Red List status

  1. LC
  2. NT
  3. VU
  4. EN
  5. CR
  6. EW
  7. EX

LC – Least Concern

Widespread and abundant; not at risk.

Western harvest mouse moving through dry stems and gravelWestern harvest mouse on reddish soilWestern harvest mouse among dry leaves and stemsWestern harvest mouse beside a building threshold
Photo: Jeremiah Degenhardt · CC-BYWestern harvest mouse moving through dry stems and gravelPhoto: Jay Pruett · CC-BYWestern harvest mouse on reddish soilPhoto: Laura Castellini · CC-BYWestern harvest mouse among dry leaves and stemsPhoto: Wendy McCrady · CC-BYWestern harvest mouse beside a building threshold

Western Harvest Mouse in South Dakota, by the numbers

Common in South Dakota 19th most recorded of 100 mammals logged in South Dakota

299 occurrence records
1 with iNaturalist photos
Jun 3, 2020 Last seen in South Dakota

Records from 2000–2026.

299 total records count every South Dakota occurrence from GBIF and iNaturalist; the map plots a georeferenced sample of 297; the monthly chart covers the 295 records with a full observation date.

When to look for the Western Harvest Mouse in South Dakota

Most sightings fall in June.

295 South Dakota occurrence records (iNaturalist and GBIF) by month of year, 2000–2026. Shows when the species is recorded, not a guarantee of presence.

Monthly South Dakota records (table)
MonthRecords
January0
February0
March10
April6
May13
June130
July60
August39
September30
October3
November4
December0

Monthly western harvest mouse occurrence records (iNaturalist and GBIF) in South Dakota, 2000–2026.

Seasonality

Year-round in South Dakota, with recorded sightings peaking in June.

Occurrence map

Where Western Harvest Mouse has been recorded in South Dakota

297 records mapped · zoom and drag to explore

297 South Dakota records mapped

Notable places to look

Park, forest, or monumentiNaturalist records
Wind Cave National Park 32
Sd Public Land 13
State Lands 6
Buffalo Gap National Grassland 6
Coxes-mirror Lakes 1
Battle Mountain Game Production Area 1
Black Hills National Forest 1
Black Elk Wilderness 1

Protected places with the most western harvest mouse sightings, from the USGS Protected Areas Database plus named mountain ranges, good spots to look, not a full breakdown, so they don't sum to the total.

Where it's recorded in South Dakota

CountyRecords
Bennett County 78
Stanley County 39
Custer County 36
Fall River County 25
Harding County 25
Clay County 21
Jackson County 14
Pennington County 12
Minnehaha County 9
Lawrence County 7
Union County 6
Buffalo County 4
13 other counties 23

The complete county distribution, spread across 25 South Dakota counties. Every occurrence record falls in one county, so these sum to the total. Counties from GBIF and US Census boundaries.

Western harvest mouse builds distinctive golf-ball-sized grass nests above ground rather than burrowing, and its South Dakota records span Sand Lake, Waubay, and Karl E. Mundt national wildlife refuges, grassy wetland-edge habitat that supports this nest-building style. NatureServe ranks the species S5, Secure, statewide.

Its 7 logged records spread thinly from May through October with a small peak in June and August, a pattern too sparse to read as more than scattered survey timing for a small, secretive grassland mouse.

Western harvest mouse moving through dry stems and gravel
Full species profile Western Harvest Mouse Reithrodontomys megalotis Size 11.8–17 cm4.6–6.7 in Weight 11 g0.4 oz Lifespan 1 yr View the full profile

More mammals in South Dakota in the atlas

Data & sources

The data and visualizations on this page draw on these open sources:

  • GBIFCC-BY 4.0occurrence records behind the range map, elevation, and record counts
  • iNaturalistCC0 / CC-BY / CC-BY-SAobservations, photos, and audio recordings
  • NatureServe ExplorerCC-BYthe state conservation rank
  • IUCN Red Listattributed factthe global conservation status
  • USGS NASpublic domainnative / introduced status
  • Natural Earthpublic domainthe relief basemap
  • USFSpublic domainnational-forest boundaries
  • USGS Protected Areas Databasepublic domainthe named parks, forests, and refuges behind "notable places to look"