Cactus Wren Genetic Study - San Diego and Orange County

Among the possible consequences of fragmentation for cactus wren viability is genetic isolation, which could lead to loss of genetic variability and ability to adapt to changing environments. In 2011, USGS scientists Barbara Kus and Amy Vandergast initiated a collaborative study to examine genetic population structure of coastal cactus wrens throughout their southern California range. In this study, researchers describe genetic connectivity in the coastal cactus wren in San Diego County. To gain a broader perspective, they also obtained samples from the Nature Reserve of orange County, where many of the remaining coastal cactus wrens are found in that county. These data provide excellent resolution for describing current population structure in the species, reveal the gene flow regime, and provide insight on current levels of genetic diversity within populations. Understanding these patterns will aid in management of current coastal cactus wrens populations and future efforts in habitat restoration. From this study, scientists found coastal cactus wrens to be highly isolated from one another in their southern California range(Barr et al. 2015). These results prompted management actions to attempt to restore connectivity among cactus wren populations, including habitat protection and restoration. The goal of Subtask 4.2 is to repeat the 2011 genetics study in the Otay, Sweetwater/San Diego and San Pasqual Valley genetic clusters. Specifically, the objectives are to: 1) Determine whether genetic diversity and effective population size have changed in the intervening 6 years with management to increase cactus scrub and improve connectivity, or in response to drought-associated population declines. 2)Prepare recommendations for managing gene flow and/or population expansion to enhance genetic diversity and effective population size.

Genetic study
Vertebrate Species
Project Groups
  • SDMMP33 Cactus Wren Genetic Analysis

Project Focus

Coastal cactus wren

coastal sage scrub

U.S. Geological Survey

Nature Reserve of Orange County

Amy Vandergast

Barbara Kus; Amy Vandergast

Kris Preston

Kelly Barr

Project Protocol
Strategic Elements
  • pre FY15-1
Project Location
Orange, Riverside, San Bernardino, San Diego
Central-central, Central-west, North-central, North-west, South-central, South-west
1, 2, 3, 4, 5, 6, 7, 8, 9
File name Lead Author Year Type
Distribution and Demography of Coastal Cactus Wrens (Campylorhynchus brunneicapillus) in Southern San Diego County, California 2021 Data Summary Lynn, Suellen; Kus, Barbara 2022 report
Genetic Connectivity in the Coastal Cactus Wren Barr, Kelly; Kus, Barbara; Vandergast, Amy 2012 report
Genetic Structure in the Cactus Wren in Coastal Southern California Barr, Kelly; Kus, Barbara; Vandergast, Amy 2013 report
Genetic structure of coastal cactus wren populations in San Diego and Orange counties Kus, Barbara; Vandergast, Amy; Preston, Kris 2011 powerpoint presentation
Recent Declines in Genetic Diversity with Limited Dispersal Among Coastal Cactus Wren Populations in San Diego County, California Vandergast, Amy; Kus, Barbara; Smith, Julia; Mitelberg, Anna 2022 journal article