San Diego Management & Monitoring Program

Vertebrate Species
American Badger Research and Monitoring


Project description

Badgers have been identified by the San Diego Monitoring and Management Program Connectivity Monitoring Strategic Plan as a target species for monitoring regional-scale functional connectivity of upland and grassland habitats. However, prior to these studies there was little information on badger distribution, movement, or habitat use within San Diego County. In 2011, the California Department of Fish and Game Local Assistance Grant funded an initial study to determine if badgers still persist in the western portion of San Diego County. Canine scent surveys were conducted for American badger scat from November 14-December 14, 2011. Thirty-two sites in San Diego County and two sites in southern Riverside County were surveyed. The scent dog had positive behavioral responses to scat at 13 sites, and a badger specific DNA test verified the scat collected at twelve sites. A recommendation from the 2011 study led researchers to develop a microsatellite DNA test to identify individual animals from scat. This would allow for estimation of minimum population sizes in areas with multiple scats. In 2014, a follow up study was conducted to the initial 2011 rapid assessment for the American badger. The objectives were to identify target areas with potentially higher densities of badgers and to better assess the level of connectivity between known occupied areas. Thirty canine scent surveys for badger scat were conducted. This study involved: 1) additional focused surveys to identify areas occupied by badgers, and 2) determination of the number of badgers at various locations using genetic tests of scat or hair to identify individuals. In 2015, researchers continued studies of the spatial and temporal use of habitats by the American badger by conducting monthly field sign and infrared camera surveys across seven focal sites in the County where we previously documented substantial and/or repeated badger activity. The objective was to determine if badger use is irregular, seasonal, or consistent. American badgers were active at two of the seven focal sites in 2015, the upper San Diego River at El Capitan Grande Reservation and Rancho Guejito. From 2011 to present, researchers established that the American badger currently occupies or uses conserved lands within MSCP and MHCP and many other portions of the county.

Project groups


Project Group: American Badger Movement Studies

Project protocol

Name: Research of American Badgers

Description: Protocol includes: canine scent surveys, badger sign surveys, scat DNA testing, hair snags, infrared cameras, and outreach efforts.

Project location

County: San Diego

Project focus

Project type: Monitoring

Target species: American badger

Target vegetation: chaparral, coastal sage scrub, grassland

Data steward: Cheryl Brehme

Investigator: Robert N. Fisher; Amy Vandergast

Main implementing entity: U.S. Geological Survey

Point of contact: Cheryl Brehme

SDMMP lead: Sarah McCutcheon

Study lead: Cheryl Brehme; Dustin Wood

Strategic elements

Budget year: pre FY15-1; Work plan objectives number:

Files and Documents

2016 American Badger Research in Western San Diego County, 2015

Author(s):Brehme, Cheryl; Fisher, Robert N.; Burlaza, Melanie

2016 Preliminary Assessment of DNA Extraction Methods and Utility of Microsatellite Genetic Assay for American Badgers

Author(s):Wood, Dustin; Mitelberg, Anna; Brehme, Cheryl; Vandergast, Amy

2015 Research of American Badgers in Western San Diego County, 2014

Author(s):Brehme, Cheryl; Hathaway, Stacie; Smith, B.H; Fisher, Robert N.