California mammals

Western Red Bat in California

Lasiurus frantzii

Native to California S3 Vulnerable 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.

Western red bat roosting among green leaves, showing rusty-orange fur and dark wing membranesWestern red bat hanging from a leafy branch with its rusty back visibleClose view of a western red bat roosting head-down in dense green foliageWestern red bat flying against a clear blue sky
Photo: Jon Robson · CC BY-SA 4.0Western red bat roosting among green leaves, showing rusty-orange fur and dark wing membranesPhoto: Dylan Camacho Guzman · CC BY 4.0Western red bat hanging from a leafy branch with its rusty back visiblePhoto: Jacek Pietruszewski · CC BY 4.0Close view of a western red bat roosting head-down in dense green foliagePhoto: Linzy L. · CC BY-SA 4.0Western red bat flying against a clear blue sky

Western Red Bat in California, by the numbers

Occasional in California 134th most recorded of 241 mammals logged in California

398 occurrence records

Records from 2000–2026.

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

When to look for the Western Red Bat in California

Most sightings fall in April.

398 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
January21
February16
March26
April86
May32
June55
July43
August29
September32
October25
November21
December12

Monthly western red bat occurrence records (iNaturalist and GBIF) in California, 2000–2026.

Seasonality

Year-round in California, with recorded sightings peaking in April, with a smaller rise in June.

Occurrence map

Where Western Red Bat 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
Golden Gate National Recreation Area 4
Humboldt Redwoods State Park 2
UCD Arboretum 2
Cleveland National Forest 2
Rancho Jamul Ecological Reserve 1
Tomales Bay State Park 1
Cabrillo National Monument 1
Landels-Hill Big Creek Reserve 1

Protected places with the most western red bat 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
Fresno County 112
San Diego County 50
Yolo County 22
Alameda County 16
Santa Clara County 15
Stanislaus County 14
Marin County 13
Butte County 13
Contra Costa County 13
Sutter County 11
Solano County 9
Riverside County 8
30 other counties 102

The complete county distribution, spread across 42 California counties. Every occurrence record falls in one county, so these sum to the total. Counties from GBIF and US Census boundaries.

California’s combined state files contain 520 Western Red Bat records: 122 from iNaturalist and 398 from GBIF. It ranks 134th among 243 mammals in this California record comparison, placing it in the middle third. That’s a ranking of submitted records, not a head count of animals.

The monthly series reaches its high point in July, with 21 records in the busiest month. Records appear in 12 of 12 months, so the pattern shows when sightings were documented, not when the species must be present or absent.

California accounts for about 80% of the mapped GBIF records summarized on the national Western Red Bat page. That’s a large share of the known record footprint, though differences in survey effort can strongly shape the percentage.

Occurrence data from iNaturalist and GBIF.

Western red bat roosting among green leaves, showing rusty-orange fur and dark wing membranes
Full species profile Western Red Bat Lasiurus frantzii Size 10–12 cm3.9–4.7 in Weight 9–15 g0.3–0.5 oz Lifespan 12 yr 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"