46 
PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES 
Series 4, Volume 64, Supplement 1 
human disturbance, which can be especially detrimental to the species during summer months, 
when these bats are rearing young. Human disturbance of caves in which they roost is a major 
threat. Because they often roost in abandoned mines, reclamation and re-working of old mines can 
severely impact populations. Because California leaf-nosed bats do not hibernate or migrate, the 
relatively warm mine shafts are critical for its survival in the northern portions of its range 
(Wikipedia 2016a). 
Family Vespertilionidae, Evening bats 
Antrozous pallidus, Pallid Bat, was formerly thought to be common in caves of central and 
southern California, but few recent records are available. A colony on the order of 100 was seen in 
Painted Rock Cave, San Luis Obispo County, in 1911 (Grinell 1918). It is known from three aban¬ 
doned mines in Inyo County (Ellison et al. 20003; U.S. Geological Survey 2016b). Perhaps 50 
were seen in Swordfish Cave on Santa Cruz Island, Santa Barbara County, in 1997-99, the only 
bats reliably reported from a California sea cave. Pallid Bat has been found in seven mines, two 
crevices, and 15 caves across the state. This species probably is a permanent resident in most of its 
range (Barbour and Davis 1969). Pallid Bat roosts in small colonies in rock crevices and buildings, 
and occasionally caves, mines, and tree cavities. (See, for example, a photo of a colony of roosting 
Pallid Bats {Antrozous pallidus ) at Madera Canyon, Santa Rita Mountains, southeastern Arizona. 
(Photo by Geoff Gallice — <http://www.flickr.com/photos/dejeuxx/4844640621/>, CC BY 2.0, 
<https://commons.wikimedia.Org/w/index.php?curid= 12165921>). 
Corynorhinus townsendii, Townsend’s big-eared bat (Fig. 83), has several subspecies with 
two in California: C. t. townsendii, western big-eared bat or Pacific Townsend’s big-eared bat, and 
C. t. pallescens, pale Townsend’s big-eared bat. The subspecies C. t. intermedins was synonymized 
with C. t. pallescens. 
Townsend’s big-eared bat is by far the most commonly reported bat in California’s caves and 
mines. Few of the recorded field identifications noted the subspecies, which are difficult to distin¬ 
guish, so our species list lumps the two subspecies. Generally C. t. townsendii occurs in most of 
northern California on the west side of the Sierra Nevada, and C. t. pallescens in the deserts. Our 
species list has 308 localities, including 123 min es and 185 caves from 31 counties in most regions 
of the state, from Klamath and Marble Mountains to Mojave Desert, Coast Ranges to Sierra 
Nevada. 
Corynorhinus t. townsendii has been a Species of Concern in California since 2013, and it was 
considered for listing by the state because of a significant loss of population size, maternity 
colonies, and hibernation colonies throughout the state. Few sites were protected, but colonies that 
have come under protection at Lava Beds National Monument, Pinnacles National Park, and 
Sequoia National Park have increased again. California denied a petition to list the subspecies as 
threatened or endangered (California Department of Fish and Wildlife 2016; Pierson and Fellers 
1998). 
Large colonies of C. t. townsendii used to exist. A colony of 1,000 was seen on July 1, 1935 
in Alice Mine, Riverside County, Mojave Desert, the largest count of this species yet reported in a 
California mine or cave. The second largest colony was 425 on June 1, 2002 in Bear Gulch Cave, 
Pinnacles National Park, San Benito County, Coast Ranges (Pierson and Fellers 1998). Two 
colonies of 210 and 230 were observed in Inyo County min es in 1992-1993 (U.S. Geological Sur¬ 
vey 2016b). 
Graham (1966) reported that disturbance by humans had caused the abandonment of several 
nursery (maternity) colonies in limestone caves. He thought that C. townsendii did not roost in 
many California limestone caves, especially for hibernation, because most of the caves are at lower 
