Basic Information
Common Name: Pallid Bat
Scientific Name: Antrozous pallidus
Species Code: ANTPAL
Management Category: SL (species at risk of loss)
Occurrence Map
Table of Occurrences
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Species Information

MSP Species Background

Goals and Objectives

Goal: Protect pallid bat diurnal, nocturnal, and maternity roosts from destruction and human disturbance and enhance foraging habitat within commuting distance of nocturnal and maternity roosts to increase resilience to environmental and demographic stochasticity, maintain genetic diversity, and improve chances of persistence over the long-term (>100 years).

regional NFO 2017 SL
MON-RES-SPEC ANTPAL-1

Management units: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11

In 2017-2018, finalize the results of research begun in 2015 on pallid bats to identify nocturnal, diurnal, and maternity roosts, foraging areas, and water sources associated with roosts in order to identify seasonal and annual changes in use and important foraging areas, and monitor reproductive status. Collect habitat covariates associated with roosting and foraging habitat, assess threats to bats at all preserves where they occur, and develop management recommendations.

Action Statement Action status Projects
RES-1 Submit project metadata, survey data, and report with management recommendations to the MSP web portal. in progress
Criteria Deadline year
Pallid Bat Surveys and Reports Completed in 2017. 2021
Threat Name Threat Code
Altered hydrologyALTHYD
Human uses of the PreservesHUMUSE
Urban developmentURBDEV
Code Obj. code Statement
ANTPAL-4 MGT-PRP-MGTPL In 2018-2019, prepare a management plan for pallid bat that prioritizes management actions to protect roosts from disturbance, ensures sufficient roosts for seasonal temperature requirements and for reproduction, and enhances foraging habitat using data from annual roost monitoring and recommendations from the pallid bat research study.
local NFO 2017, 2018, 2019, 2020, 2021 SL
MON-IMP-IMG ANTPAL-2

Management units: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11

Beginning in 2017, inspect the vicinity of pallid bat roosts on an annual basis (see occurrence table), taking care not to disturb bats, and use a regional monitoring protocol to collect covariate data on human activities and other threats to determine management needs.

Action Statement Action status Projects
IMP-1 Conduct regional IMG monitoring protocol surveys to quantify signs of human activity near occupied or potential roosts and to identify other potential threats. Care should be taken to avoid disturbing roosting bats. available for implementation Pallid Bat Surveys - Sweetwater Marsh
IMP-2 Based upon threat evaluation, determine if routine management or more intensive management is warranted. available for implementation Pallid Bat Surveys - Sweetwater Marsh
IMP-3 Submit monitoring data and management recommendations to MSP web portal available for implementation Pallid Bat Surveys - Sweetwater Marsh
Criteria Deadline year
Annual IMG monitoring of Pallid bat completed 2021
Threat Name Threat Code
Human uses of the PreservesHUMUSE
Urban developmentURBDEV
Code Obj. code Statement
ANTPAL-1 MON-RES-SPEC In 2017-2018, finalize the results of research begun in 2015 on pallid bats to identify nocturnal, diurnal, and maternity roosts, foraging areas, and water sources associated with roosts in order to identify seasonal and annual changes in use and important foraging areas, and monitor reproductive status. Collect habitat covariates associated with roosting and foraging habitat, assess threats to bats at all preserves where they occur, and develop management recommendations.
local NFO 2017, 2018, 2019, 2020, 2021 SL
MGT-IMP-IMG ANTPAL-3

Management units: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11

Beginning in 2017, conduct routine management actions identified through the IMG regional protocol monitoring, including protecting occurrences from disturbance through fencing, signage, and enforcement.

Action Statement Action status Projects
IMP-1 Perform routine management activities such as protecting occurrences from disturbance through fencing, signage, and enforcement. available for implementation
IMP-2 Submit project metadata and management data to the MSP web portal. available for implementation
Criteria Deadline year
Routine Management Completed as Needed Based Upon Monitoring Recommendations 2021
Threat Name Threat Code
Human uses of the PreservesHUMUSE
Urban developmentURBDEV
Code Obj. code Statement
ANTPAL-2 MON-IMP-IMG Beginning in 2017, inspect the vicinity of pallid bat roosts on an annual basis (see occurrence table), taking care not to disturb bats, and use a regional monitoring protocol to collect covariate data on human activities and other threats to determine management needs.
regional NFO 2018, 2019 SL
MGT-PRP-MGTPL ANTPAL-4

Management units: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11

In 2018-2019, prepare a management plan for pallid bat that prioritizes management actions to protect roosts from disturbance, ensures sufficient roosts for seasonal temperature requirements and for reproduction, and enhances foraging habitat using data from annual roost monitoring and recommendations from the pallid bat research study.

Action Statement Action status Projects
PRP-1 Prioritize management actions, focusing on reducing threats and expanding occurrences in areas most likely to remain viable over the long-term in the context of future land development. available for implementation Pallid Bat Surveys - Sweetwater Marsh
PRP-2 Develop a management plan for pallid bat that prioritizes management actions for the next five years. waiting for precedent action Pallid Bat Surveys - Sweetwater Marsh
PRP-3 Identify areas where pallid bat and Townsend?s big-eared bat management can be complimentary. waiting for precedent action Pallid Bat Surveys - Sweetwater Marsh
PRP-4 Submit management plan to MSP web portal waiting for precedent action Pallid Bat Surveys - Sweetwater Marsh
Criteria Deadline year
Management Plan for Pallid bat prepared by 2018 2021
Threat Name Threat Code
Altered hydrologyALTHYD
Human uses of the PreservesHUMUSE
Urban developmentURBDEV
Code Obj. code Statement
ANTPAL-1 MON-RES-SPEC In 2017-2018, finalize the results of research begun in 2015 on pallid bats to identify nocturnal, diurnal, and maternity roosts, foraging areas, and water sources associated with roosts in order to identify seasonal and annual changes in use and important foraging areas, and monitor reproductive status. Collect habitat covariates associated with roosting and foraging habitat, assess threats to bats at all preserves where they occur, and develop management recommendations.
ANTPAL-2 MON-IMP-IMG Beginning in 2017, inspect the vicinity of pallid bat roosts on an annual basis (see occurrence table), taking care not to disturb bats, and use a regional monitoring protocol to collect covariate data on human activities and other threats to determine management needs.
ANTPAL-3 MGT-IMP-IMG Beginning in 2017, conduct routine management actions identified through the IMG regional protocol monitoring, including protecting occurrences from disturbance through fencing, signage, and enforcement.
regional and/or local NFO 2020, 2021 SL
MGT-IMP-MGTPL ANTPAL-5

Management units: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11

Beginning in 2020, implement highest priority management actions for pallid bats on Conserved Lands.

Action Statement Action status Projects
IMP-1 Management actions to be determined by the implementation plan. waiting for precedent action
IMP-2 Submit project data and management actions to MSP web portal waiting for precedent action
Criteria Deadline year
Management actions implemented for Pallid bat 2021
Threat Name Threat Code
Altered hydrologyALTHYD
Human uses of the PreservesHUMUSE
Urban developmentURBDEV
Code Obj. code Statement
ANTPAL-4 MGT-PRP-MGTPL In 2018-2019, prepare a management plan for pallid bat that prioritizes management actions to protect roosts from disturbance, ensures sufficient roosts for seasonal temperature requirements and for reproduction, and enhances foraging habitat using data from annual roost monitoring and recommendations from the pallid bat research study.
regional and/or local NFO 2020, 2021 SL
MON-IMP-MGTPL ANTPAL-6

Management units: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11

Beginning in 2020, monitor the effectiveness of management actions implemented for pallid bats on Conserved Lands.

Action Statement Action status Projects
IMP-1 Submit monitoring data and reports to MSP web portal waiting for precedent action
Criteria Deadline year
Effectiveness of Implementing Pallid Bat High Priority Actions Determined 2021
Threat Name Threat Code
Altered hydrologyALTHYD
Human uses of the PreservesHUMUSE
Urban developmentURBDEV
Code Obj. code Statement
ANTPAL-5 MGT-IMP-MGTPL Beginning in 2020, implement highest priority management actions for pallid bats on Conserved Lands.

Caution

Overall Condition

Unknown

Overall Trend

Low

Overall Confidence
Metric Condition Trend Confidence
1. Species Richness

Percent of sites with a richness score greater than 7


Good

Unknown

Low
2. Pallid and Townsend's big-eared bat detections

Percent of sites with a pallid bat and/or a Townsend's big-eared bat detections


Caution

Unknown

Low
Current Status
The current overall condition status of the Bats Species Indicator is Caution based on the two metric condition values we selected. More high-quality data are needed to determine trends. While it is uncertain whether bat diversity is declining across the MSPA (Metric1), there are indications some populations may be declining, such as for pallid and Townsend's big-eared bats (Metric 2). Future metrics are planned to assess threats to roosting and foraging habitats for the bat community and effectiveness of management actions.
Metrics Dashboard
Full metric information for this species is available on our Dashboard.
Metrics Dashboard
Bat Community Management and Monitoring
Both the pallid bat (Antrozous pallidus) and Townsend’s big-eared bat (Corynorhinus townsendii), have been proposed as covered species in the North County MSCP plan and are included in the MSP. These two species are believed to be at high to moderate risk of loss in the MSP area because of their low numbers and sensitivity to human disturbance. However, their population status, locations of roosts (diurnal, nocturnal, and maternity), primary foraging areas, water sources used, threats, and connectivity between populations in the MSP area are largely unknown. For this reason, San Diego County-wide surveys for these species were needed to document where they were found and what their current population status was. Information gleaned from these surveys will allow land managers to implement appropriate management actions to conserve their habitats. The MSP identified this work as a priority for implementation starting in 2015. In 2015, the SDNHM under contract to USGS surveyed areas with known pallid and Townsend's big-eared bat occurrences as identified in the MSP and in other high potential sites based on previous survey work by USGS and the SDNHM. A variety of methods were used (roost surveys, mist-netting, acoustic surveys, etc.) to identify and map the primary roosts and foraging areas used by pallid bat and Townsend's big-eared bat.
Bat Management in San Diego County
This is a planned 2-year Study. In 2015 and 2016, the SDNHM, under contract to USGS, will survey areas with known pallid and Townsend's big-eared bat occurrences in MUs 3, 4, 5, 6 and 8 as identified in the MSP and in other high potential sites based on previous survey work by USGS and the SDNHM, including areas in North County and potentially areas adjacent to the MSP.
Pallid Bat Surveys - Sweetwater Marsh
The Living Coast Discovery Center, in partnership with the U.S. Fish and Wildlife Service, Cabrillo National Monument, and the San Diego National History Museum will conduct surveys to determine bat species composition on and around the Sweetwater Marsh Unit of the San Diego Bay National Wildlife Refuge. The primary goals of this project are to establish permanent survey locations within Sweetwater Marsh, to contribute to the data collection in regional bat studies, and to establish site-specific bat habitat threat reduction and management plan based on the survey results. Strong historical research suggests that the pallid bat is likely utilizing Sweetwater Marsh for foraging and roosting at this time, This project will enable the Living Coast to contribute to larger regional conservation efforts, working with USFWS to improve the management of Sweetwater Marsh to mitigate environmental threats to the pallid bat, and contribute to the general public's greater awareness of local MSP species in San Diego. Funding this program will significantly leverage SANDAG's conservation efforts by awardee- The San Diego National History Museum- funded by Environmental Mitigation Program funds.
SR 94 Wildlife Infrastructure Plan
Proposed road improvements to SR 94 provide an opportunity to mitigate the potential barrier effects of the highway. This project identifies where improvements to existing infrastructure on SR-94 could improve connectivity across the South County preserves, using Best Management Practices from the scientific literature; recommends wildlife movement monitoring to identify where new crossings are needed; and identifies where additional conservation would enhance the integrity of South County linkages. The review prioritizes infrastructure improvements of 35 existing undercrossings inspected by wildlife experts in the field along 14.6 miles of SR-94 where the highway bisects conserved lands. The majority of the recommendations for infrastructure improvement focus on increasing the diameter, and thus the openness ratio (cross-sectional area divided by length), of the undercrossing itself, removing vegetation and debris blocking the undercrossing, restoring habitat in the approach to the undercrossing, and installing fencing to both (1) keep animals off the highway and (2) funnel wildlife to the undercrossings.
File name Lead Author Year Type
Bat communities of Rancho Jamul Ecological Reserve and Santa Ysabel Open Space Preserve before and after 2003 wildfires Rochester, Carlton; Backlin, Adam R.; Stokes, Drew; Mitrovich, Milan; Brehme, Cheryl; Fisher, Robert N. 2010 report
Bat Management in San Diego County Myers, Brian; Stokes, Drew; Preston, Kris; Fisher, Robert N.; Vandergast, Amy 2022 powerpoint presentation
DRAFT Final report for focused pallid bat (Antrozous pallidus) and Townsend’s big-eared bat (Corynorhinus townsendii) surveys in San Diego County, California 2018 report
Pallid Bat: Final Report 2018 report
Recording - May 2022 SDMMP Management and Monitoring Coordination Meeting Fisher, Robert N.; Vandergast, Amy; Myers, Brian 2022 recording
State of the Regional Preserve System in Western San Diego County Preston, Kris; Perkins, Emily; Brown, Chris; McCutcheon, Sarah; Bernabe, Annabelle; Luciani, Emilie; Kus, Barbara; Wynn, Susan 2022 report

Current Distribution Rangewide

Ranges throughout western North America, from British Columbia's southern interior, south to Queretaro and Jalisco, and east to Texas [1]. Common throughout arid deserts and grasslands in the southwestern U.S. [2]. Distribution in Washington and Oregon includes Sonoran and Transitional life zones. Occurs throughout most of California except for the high Sierra Nevada Mountains and the northwestern corner of the state [3]. Historically abundant in the coastal plains, inland valleys, and western foothills of San Diego County [4 cited from 5].

Known Populations in San Diego County

Occurrences found in Buena Vista Lagoon Ecological Reserve, Kendall Frost Marsh, Tijuana Slough National Wildlife Refuge, Tijuana River Valley Regional Park, San Diego River Park, San Diego Bay National Wildlife Refuge, Torrey Pines State Natural Reserve, Agua Hedionda-SDGE, San Elijo Lagoon Ecological Reserve, Escondido Creek Preserve, Agua Hedionda Lagoon Ecological Reserve, San Luis Rey River Park, Batiquitos Lagoon Ecological Reserve, Flood Control Channel Southern Wildlife Preserve, San Dieguito River Park, Buena Vista Lagoon Ecological Reserve, San Dieguito Lagoon, Otay Lakes Cornerstone Lands, Los Penasquitos Canyon Preserve, and Torrey Pines

List Status

SSC

Habitat Affinities

Occurs in a wide variety of habitats, including grasslands, shrublands, woodlands, and forests. Most common in open, dry habitats with rocky areas for roosting [3]. A yearlong resident over most of its range, often found roosting in rural man-made structures such as barns or other infrequently used buildings [4 cited from 5]. Locally common species of low elevations in California [3].

Taxonomy and Genetics

Member of the taxonomic Order Chiroptera and Family Vespertilionidae and is currently the only member of its genus [6].

Seasonal Activity

Nocturnal. Emerges late (30-60 min after sunset), with a major activity peak 90-190 min after sunset, and a second peak shortly before dawn. Brief foraging periods occur in autumn, and activity is infrequent below 2°C. Undergoes shallow torpor daily. Hibernates in winter near the summer day roost [2]. Duration of the daytime roosting period differs sharply from season to season, probably at least partly in response to day length, temperature, and insect abundance [7].

Life History/Reproduction

Maternity colonies form in early April, and may have a dozen to 100 individuals. Males may roost separately or in the nursery colony [3]. Mates from late October-February. Fertilization is delayed, gestation is 53-71 days. Young are born from April-July, mostly from May-June. Litter size is 1-3. Average litter is 2, but females reproducing for the first time usually have 1 young. Altricial young are weaned in 7 weeks and are observed flying in July and August. Females nurse only their own young. Females and juveniles forage together after weaning. Females mate in first autumn, males in second. Maximum recorded longevity is 9 yr,1 mo [8].

Diet and Foraging

Takes a wide variety of insects and arachnids, including beetles, orthopterans, homopterans, moths, spiders, scorpions, solpugids, and Jerusalem crickets. It is able to consume large, hard-shelled prey [9]. Foraging is concentrated in two periods at the beginning and end of the nocturnal cycle of activity during most of the active season [2]. Occurs over open ground, usually 0.5-2.5 m above ground level. Flight is slow and maneuverable with frequent dips, swoops, and short glides. Many prey are taken on the ground. Gleaning frequently used and a few prey are taken aerially. Can maneuver well on the ground. May carry large prey to a perch or night roost for consumption. Uses echolocation for obstacle avoidance; possibly utilizes prey-produced sounds while foraging [3]. Usually found foraging in oak savannah-type habitats, grassy oak and sycamore-lined river terraces, native grasslands, and sparsely vegetated scrublands [4 cited from 5].

Dispersal

Forages 0.5-2.5 km (1-3 mi) from day roost. Capable of homing from distances of a few miles, but not further [3].

Threats

Threatened by damage and destruction of roosts and hibernacula through vandalism, mine closures and reclamation, recreational activities such as rock climbing, and forestry practices such as timber harvest. Roosts and hibernicula are also threatened when man-made structures are occupied, demolished, modified, have chemical treatments applied, or when bats are intentionally eradicated and excluded. Other threats include loss or modification of foraging habitat due to prescribed fire, urban development, agricultural expansion, and/or pesticide use [1;10].

Literature Sources

[1] Sherwin, R. 2005. Pallid Bat. Western Bat Working Group. Available from: http://wbwg.org/western-bat-species/. Accessed September 20 2016.

[2] Hermanson, J. W., and T. J. O’Shea. 1983. Antrozous pallidus. Mammalian Species Archive 213: 1-8.

[3] Harris, J. Pallid Bat. Zeiner, D.C., W.F.Laudenslayer, Jr., K.E. Mayer, and M. White, eds. 1988-1990. California's Wildlife. Vol. I-III. California Department of Fish and Game, Sacramento, California.

[4] Krutzsch, P. H. 1948. Ecological study of the bats of San Diego County, California. PhD diss., University of California.

[5] Stokes, D. C., C. S. Brehme, S. A. Hathaway, and R. N. Fisher. 2005. Bat inventory of the San Diego County Multiple Species Conservation Program Area. US Geological Survey.

[6] Yolo Conservation Plan, Species Accounts: Pallid Bat. 2009 (April). Available from: http://www.yoloconservationplan.org/yolo_pdfs/speciesaccounts/mammals/pallid-bat.pdf. Accessed September 20, 2016.

[7] Vaughan, T. A., and T. J. O'Shea. 1976. Roosting ecology of the pallid bat, Antrozous pallidus. Journal of Mammalogy 57, no. 1: 19-42.

[8] Cockrum, E. L. 1973. Additional longevity records for American bats. Journal of the Arizona Academy of Science 8, no. 3: 108-110.

[9] Freeman, P. W. 1981. Correspondence of food habits and morphology in insectivorous bats. Journal of Mammalogy 62, no. 1: 166-173.

[10] Miner, K. L. and D. C. Stokes. 2005. Bats in the south coast ecoregion: status, conservation issues, and research needs. US Forest Service.