California mammals

Humboldt's Flying Squirrel in California

Glaucomys oregonensis

Native to California SNR Unranked in California

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

IUCN Red List status

NE – Not Evaluated

Not yet assessed against IUCN Red List criteria.

Live Humboldt's flying squirrel perched on pine needles beside a pinecone, feeding with front paws tucked to its mouthFlying Squirrel Released Back to Nature (8551613859)Glaucomys oregonensisGlaucomys oregonensis2
Photo: Chris Brown · CC BY 4.0Live Humboldt's flying squirrel perched on pine needles beside a pinecone, feeding with front paws tucked to its mouthPhoto: Pacific Southwest Region 5 · Public domainFlying Squirrel Released Back to Nature (8551613859)Photo: Barbogast · CC BY-SA 4.0Glaucomys oregonensisPhoto: Barbogast · CC BY-SA 4.0Glaucomys oregonensis2

Humboldt's Flying Squirrel in California, by the numbers

Common in California 74th most recorded of 241 mammals logged in California

665 occurrence records
665 with iNaturalist photos

Records from 2000–2026.

665 total records count every California occurrence from GBIF and iNaturalist; the map plots a georeferenced sample of 300.

When to look for the Humboldt's Flying Squirrel in California

Most sightings fall in July to August.

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

Monthly California records (table)
MonthRecords
January19
February34
March3
April9
May27
June35
July132
August219
September68
October90
November21
December8

Monthly humboldt's flying squirrel occurrence records (iNaturalist and GBIF) in California, 2000–2026.

Seasonality

Year-round in California, with recorded sightings peaking in July–August.

Occurrence map

Where Humboldt's Flying Squirrel has been recorded in California

300 records mapped · zoom and drag to explore

300 California records mapped

Notable places to look

Park, forest, or monumentiNaturalist records
Redwood National Park 7
Caribou Wilderness 6
Tahoe National Forest 5
Giant Sequoia National Monument 3
Lake Tahoe 2
Sequoia National Park 2
Stanislaus National Forest 2
Lassen National Forest 2

Protected places with the most humboldt's flying squirrel 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 California

CountyRecords
San Bernardino County 537
Humboldt County 25
Lassen County 16
El Dorado County 12
Nevada County 10
Tuolumne County 8
Siskiyou County 8
Fresno County 7
Placer County 7
Tulare County 6
Calaveras County 4
Del Norte County 4
11 other counties 21

The complete county distribution, spread across 23 California counties. Every occurrence record falls in one county, so these sum to the total. Counties from GBIF and US Census boundaries.

Humboldt records follow California’s cooler uplands and forests more closely than the hot Central Valley floor. The Sierra Nevada, Klamath Mountains, and Coast Ranges aren’t interchangeable: snow, summer moisture, tree cover, and elevation shape where reports appear.

Road access and popular trails make some mountain belts much better documented than remote forest. A dense group of reports can identify a well-watched area, but it doesn’t prove that the species is more numerous there.

The California record set contains 665 research-grade community observations. Monthly patterns can also reflect weather and observer activity, so they shouldn’t be treated as a direct count of animals.

Occurrence data from iNaturalist.

Live Humboldt's flying squirrel perched on pine needles beside a pinecone, feeding with front paws tucked to its mouth
Full species profile Humboldt's Flying Squirrel Glaucomys oregonensis View the full profile

More mammals in California 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"