Wyoming mammals

Western Deer Mouse in Wyoming

Peromyscus sonoriensis

Native to Wyoming S5 Secure in Wyoming

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

IUCN Red List status

NE – Not Evaluated

Not yet assessed against IUCN Red List criteria.

Western deer mouse sheltering in a rock creviceWestern deer mouse sniffing gravel with its white feet visibleWestern deer mouse close-up showing its large ears and long whiskers
Photo: Logan Stecker · CC0Western deer mouse sheltering in a rock crevicePhoto: Aerin Jacob · CC BY 4.0Western deer mouse sniffing gravel with its white feet visiblePhoto: Liam Steele · CC0Western deer mouse close-up showing its large ears and long whiskers

Western Deer Mouse in Wyoming, by the numbers

Occasional in Wyoming 70th most recorded of 126 mammals logged in Wyoming

61 occurrence records
39 with iNaturalist photos
Jul 9, 2026 Last seen in Wyoming

Records from 2000–2026.

61 total records count every Wyoming occurrence from GBIF and iNaturalist; the monthly chart covers the 60 records with a full observation date.

When to look for the Western Deer Mouse in Wyoming

Most sightings fall in September.

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

Monthly Wyoming records (table)
MonthRecords
January2
February0
March1
April1
May3
June5
July11
August8
September25
October3
November0
December1

Monthly western deer mouse occurrence records (iNaturalist and GBIF) in Wyoming, 2000–2026.

Seasonality

Year-round in Wyoming, with recorded sightings peaking in September.

Occurrence map

Where Western Deer Mouse has been recorded in Wyoming

61 records mapped · zoom and drag to explore

61 Wyoming records mapped

Notable places to look

Park, forest, or monumentiNaturalist records
Yellowstone National Park 30
Grand Teton National Park 4
Gros Ventre Wilderness 3
State Lands 1111112520 1

Protected places with the most western deer 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 Wyoming

CountyRecords
Park County 26
Teton County 20
Fremont County 3
Albany County 3
Johnson County 2
Niobrara County 1
Sweetwater County 1
Uinta County 1
Crook County 1
Laramie County 1
Sheridan County 1
Washakie County 1

The complete county distribution, spread across 12 Wyoming counties. Every occurrence record falls in one county, so these sum to the total. Counties from GBIF and US Census boundaries.

Western deer mouse records in Wyoming concentrate in Yellowstone and Grand Teton national parks and Bridger-Teton National Forest, a spread that reflects a habitat generalist found from sagebrush flats to subalpine forest across the ecosystem.

Reports climb through summer and peak at 25 in September, likely tracking late-season trapping-survey timing as much as the mouse’s own activity calendar. NatureServe ranks the species S5, Secure, in Wyoming.

Occurrence data from iNaturalist.

Western deer mouse sheltering in a rock crevice
Full species profile Western Deer Mouse Peromyscus sonoriensis Size 12–20 cm4.7–7.9 in Weight 15–32 g0.5–1.1 oz Lifespan 1 yr View the full profile

More mammals in Wyoming 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"