California mammals

Mexican Free-tailed Bat in California

Tadarida brasiliensis

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

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

LC – Least Concern

Widespread and abundant; not at risk.

Tadarida brasiliensis - Bahamas - Long Island (sic) - Cartwright Cave - March 2006 - 2A dense column of Mexican free-tailed bats streaming from beneath a highway bridge at duskMexican free-tailed bats pouring into the evening sky as onlookers watch below
Photo: Matti Mero · Public domainTadarida brasiliensis - Bahamas - Long Island (sic) - Cartwright Cave - March 2006 - 2Photo: James Todd McCann · CC BY 4.0A dense column of Mexican free-tailed bats streaming from beneath a highway bridge at duskPhoto: Theo Summer · CC0Mexican free-tailed bats pouring into the evening sky as onlookers watch below

Mexican Free-tailed Bat in California, by the numbers

Common in California 60th most recorded of 241 mammals logged in California

2,849 occurrence records
842 with iNaturalist photos

Records from 2000–2026.

2,849 total records count every California occurrence from GBIF and iNaturalist; the map plots a georeferenced sample of 300; the monthly chart covers the 2,817 records with a full observation date.

When to look for the Mexican Free-tailed Bat in California

Most sightings fall in July to October.

2,817 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
January132
February207
March263
April281
May201
June185
July370
August329
September296
October346
November160
December47

Monthly mexican free-tailed bat occurrence records (iNaturalist and GBIF) in California, 2000–2026.

Seasonality

Year-round in California, with recorded sightings peaking in July–October, with a smaller rise in March–April.

Occurrence map

Where Mexican Free-tailed 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
Yolo Bypass Wildlife Area 64
Phillip Burton Wilderness Area 24
Death Valley National Park 14
Sequoia National Park 10
Riverside Mountains Wilderness Area 10
Fort Tejon State Historic Park 9
Gray Lodge Wildlife Area 8
Channel Islands National Park 7

Protected places with the most mexican free-tailed 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
San Diego County 270
Yolo County 260
Los Angeles County 251
Santa Clara County 159
Alameda County 120
San Bernardino County 110
Kern County 104
San Francisco County 96
Monterey County 90
Marin County 84
San Joaquin County 79
San Luis Obispo County 76
40 other counties 1,150

The complete county distribution, spread across 52 California counties. Every occurrence record falls in one county, so these sum to the total. Counties from GBIF and US Census boundaries.

Mexican free-tailed bat reports link California’s warm valleys and deserts with caves, bridges, and buildings used for daytime shelter. The Salton Sea and other open-water areas can concentrate flying insects, while developed corridors provide roosts that are easier to monitor than remote cliffs.

Records remain broad from March through October, with the largest monthly total in July and another rise in October. Warm nights support insect hunting, and autumn movement may add detections. Klamath Basin and San Francisco Bay lie in cooler settings, so California’s statewide curve blends very different local seasons and survey effort.

Occurrence data from iNaturalist and GBIF.

Tadarida brasiliensis - Bahamas - Long Island (sic) - Cartwright Cave - March 2006 - 2
Full species profile Mexican Free-tailed Bat Tadarida brasiliensis Size 3.1–4.1 cm1.2–1.6 in Weight 7–12 g0.2–0.4 oz Lifespan 8 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"