Photo Credit: Alexandra Houston, USGS
Photo Credit: Alexandra Houston, USGS
Goal: Protect, enhance, and restore suitable cactus scrub habitat for coastal cactus wrens to increase effective population size in each genetic cluster at a short term sustainable level (e.g. 50-100 wrens), rehabilitate habitat destroyed by wildfire, improve habitat quality to maintain populations during drought, enhance connectivity within and between genetic clusters to increase genetic diversity and rescue small populations, and manage anthropogenic predation risk to ensure the long term persistence (>100 years) of cactus wrens on Conserved Lands in the MSPA.
Management units: 2, 3, 4
From 2017 through 2021, continue implementing high priority management actions to: expand coastal cactus wren populations; rehabilitate habitat destroyed in the 2003 Cedar and 2007 Harris wildfires; improve connectivity within and between the Otay and San Diego/El Cajon genetic clusters (see occurrence table); and manage high risk of anthropogenic predation of adults and nestlings. These priority management actions are identified in the South San Diego County Coastal Cactus Wren Habitat Conservation and Management Plan prepared in 2015.
| Action | Statement | Action status | Projects |
|---|---|---|---|
| IMP-1 | Following best practices in the South San Diego County Coastal Cactus Wren Habitat Conservation and Management Plan, design cactus scrub enhancement and restoration projects to provide high quality nesting and foraging habitat with large patches of cacti >1 m tall in a mosaic of open scrub that provides sufficient food resources for reproduction and survival, especially during drought. As they become available, incoporate the results from the Cactus Wren Demography, Foraging and Arthropod Study to create restoration palettes that favor plant species associated with important arthropod food resources. Design planting layouts to maximize water availability by allocating a portion of the plantings to more mesic sites, such as ravines, at the bottom of slopes, and on northerly and easterly aspects. Control invasive nonnative plants to =20% absolute cover to reduce competition with native plants for water and light. | some occurrences are in progress | Otay River Valley Cactus Wren Habitat Restoration and Enhancement , Salt Creek Coastal Cactus Wren Habitat Restoration Project |
| IMP-2 | Implement management actions, as needed, to reduce anthropogenic predation on wrens and their nests in fragmented habitats bordered by development where wrens are vulnerable to predation by cats, Cooper's hawks, corvids and other human-subsidized predators. Actions could include removing selected trees within or bordering cactus scrub that provide hunting, roosting, and nesting perches for hawks and corvids and avoiding cactus scrub restoration in areas where the terrain and location make wrens especially vulnerable to predation. Other measures could involve humanely removing feral cats from Conserved Lands and providing educational material and signage encouraging neighboring homeowners to keep their cats indoors so that wrens are protected and cats are safe from predation by wild animals, such as coyotes. | some occurrences are in progress | Otay River Valley Cactus Wren Habitat Restoration and Enhancement , Salt Creek Coastal Cactus Wren Habitat Restoration Project |
| Criteria | Deadline year |
|---|---|
| By 2021, =3 High Priority Management Actions Implemented from the 2015 South San Diego County Coastal Cactus Wren Habitat Conservation and Management Plan | 2021 |
| Threat Name | Threat Code |
|---|---|
| Altered fire regime | ALTFIR |
| Climate change | CLICHN |
| Herbivory/predation | |
| Invasive plants | INVPLA |
| Loss of connectivity | LOSCON |
| Urban development | URBDEV |
Management units: 2, 3, 4
From 2017-2021, collect data on the effectiveness of implementing high priority management actions from the 2015 South San Diego County Coastal Cactus Wren Habitat Conservation and Management Plan. In 2021, compile data from all restoration projects and determine the effectiveness of cumulative management actions for the combined Otay and San Diego/El Cajon genetic clusters (see occurrence table) in south San Diego County. These results will be used in 2022 to update management recommendations and success criteria for the South San Diego County Coastal Cactus Wren Habitat Conservation and Management Plan.
| Action | Statement | Action status | Projects |
|---|---|---|---|
| IMP-1 | Collect vegetation data to document success of cactus scrub restoration projects. This can include monitoring the height, diameter and survival of planted cactus and the composition and percent cover of native and nonnative shrubs, forbs and grasses. Document wren use of restored cactus scrub. | some occurrences are in progress | |
| IMP-2 | Submit restoration and enhancement project metadata, management datasets, and reports to the MSP Web Portal. | in progress | |
| IMP-3 | Conduct a meta-analysis of habitat restoration data and cactus wren population survey data to determine whether short-term success criteria have been achieved for habitat restoration actions and for wren populations in south San Diego County. Based upon these results, prepare recommendations for the 2022-2031 management strategy for coastal cactus wren. These broad recommendations can be used in 2022 to update the South San Diego County Coastal Cactus Wren Habitat Conservation and Management Plan with the next set of success criteria and specific, prioritized management actions. | waiting for precedent action | |
| IMP-4 | Submit cactus wren habitat restoration and population meta-analysis datasets, results, and management strategy recommendations for south San Diego County to the MSP Web Portal. | waiting for precedent action |
| Criteria | Deadline year |
|---|---|
| Success Criteria 2013-2021: Restore =70 Acres of High Quality Cactus Scrub and Increase the Combined Otay and San Diego/El Cajon Genetic Clusters to =75 Territories on C | 2021 |
| Threat Name | Threat Code |
|---|---|
| Altered fire regime | ALTFIR |
| Climate change | CLICHN |
| Herbivory/predation | |
| Invasive plants | INVPLA |
| Loss of connectivity | LOSCON |
| Urban development | URBDEV |
Management units: 2, 3, 4, 6
From 2017 to 2021, use a standardized protocol to survey for cactus wrens to determine territory, pairing and banding status and collect habitat covariate data in cactus scrub habitats on Conserved Lands in the Otay and San Diego/El Cajon genetic clusters (see occurrence table). In 2018 and 2021, expand surveys to include the San Pasqual Valley/Lake Hodges genetic cluster.
| Action | Statement | Action status | Projects |
|---|---|---|---|
| SURV-1 | Conduct 2 rounds of protocol surveys each year for coastal cactus wrens in mapped cactus at long term monitoring sites and expand monitoring sites, as needed, to include restoration sites and newly conserved cactus scrub. Use standardized protocols to document the number of wrens observed, age, sex, pairing and nesting status, and color band combinations, and to assess habitat for shrub overgrowth and crowding, invasive plants, unhealthy or dead cactus, and dominant shrub and cactus species. Update cactus mapping at restored and newly conserved sites. | in progress | |
| SURV-2 | In conjunction with the Coastal Cactus Wren Demography, Vegetation and Arthropod Study, focus on collecting banding status data to better understand cactus wren population dynamics, adult and juvenile survival, and dispersal capabilities in south San Diego County. | unknown | |
| SURV-3 | Submit project metadata, cactus wren survey and habitat assessment datasets, analyses and survey reports to the MSP Web Portal. | in progress |
| Criteria | Deadline year |
|---|---|
| Cactus Wren Surveys and Habitat Assessments Completed 2017-2021 | 2021 |
| Threat Name | Threat Code |
|---|---|
| Altered fire regime | ALTFIR |
| Climate change | CLICHN |
| Herbivory/predation | |
| Invasive plants | INVPLA |
| Loss of connectivity | LOSCON |
| Urban development | URBDEV |
Management units: 2, 3, 4
From 2017 to 2019, continue the Coastal Cactus Wren Demography, Vegetation and Arthropod Study begun in 2015 to investigate relationships between habitat quality and wren reproduction, dispersal and survival in the Otay and San Diego/El Cajon genetic clusters (see occurrence table). Habitat quality is measured at the territory scale and characterized by vegetation attributes, arthropod community composition, nestling diet, and potential availability of arthropod prey based on plant associations. Use the results to develop specific restoration recommendations to enhance habitat suitability and food resources important to cactus wren reproduction and survival.
| Action | Statement | Action status | Projects |
|---|---|---|---|
| RES-1 | Capture, uniquely color band, and monitor cactus wrens regularly during the breeding season to collect data on territory and breeding status, nesting phenology, nest fate, number of eggs/nestlings/fledglings per nest, and annual productivity, dispersal and survival. Measure habitat quality at each territory by characterizing the vegetation and by sampling arthropod communities associated with bare ground and 8 plant species common to cactus scrub. Determine nestling diets by collecting fecal samples during banding and using DNA barcoding methods to identify the arthropod taxa fed to nestlings. | in progress | |
| RES-2 | Identify arthropods important in the diet of nestling cactus wrens based on a DNA barcoding identification of arthropods in fecal samples obtained from the south San Diego County study, from the results of a similar study in Orange County, and from a literature search of adult and nestling cactus wren diets across their range. Evaluate the occurrence of arthropod taxa important to wren diets in association with 8 specific plant species and bare ground to determine those habitat attributes in cactus scrub that provide significant food resources for cactus wrens. Analyze wren reproductive parameters in relation to expected arthropod food availability based on the habitat attributes of each territory. Use the results to develop specific management recommendations for plant restoration palettes and for restoring the composition and cover of plants and bare ground that enhance food availablity for wrens. Determine how plants might be situated in the landscape to enhance arthropod food availability during droughts, such as planting a portion of plants in more mesic sites in ravines, at the bottom of slopes and on northerly and easterly aspects. | in progress | |
| RES-3 | Project metadata, datasets, analyses, and report with specific management recommendations will be submitted to the MSP Web Portal. | in progress |
| Criteria | Deadline year |
|---|---|
| Coastal Cactus Wren Demography, Vegetation and Arthropod Study and Report with Management Recommendations Completed by 2020 | 2021 |
| Threat Name | Threat Code |
|---|---|
| Altered fire regime | ALTFIR |
| Climate change | CLICHN |
| Herbivory/predation | |
| Invasive plants | INVPLA |
| Urban development | URBDEV |
Management units: 2, 3, 4, 6
From 2017-2019, in conjunction with standardized surveys and with banding activities for the Coastal Cactus Wren Demography, Vegetation and Arthropod Study, collect feather or blood samples from nestling and adult cactus wren at sites where wrens were sampled in 2011-2012 for the Southern California Cactus Wren Genetics Study (Barr et al. 2013, 2015). Determine if genetic diversity and effective population size have changed in the Otay, San Diego/El Cajon, and San Pasqual genetic clusters (see occurrence table) and evaluate whether there are potential threats to long-term population sustainability from inbreeding. Based on these results, prepare specific recommendations for managing gene flow and/or population expansion to enhance genetic diversity and effective population size.
| Action | Statement | Action status | Projects |
|---|---|---|---|
| RES-1 | Collaborate with the Natural Community Coalition to repeat the 2012 Southern California Coastal Cactus Wren Genetics Study (Barr et al. 2013, 2015) for the Coastal Orange County-Camp Pendleton, San Diego/El Cajon, Otay, and San Pasqual genetic clusters. Evaluate whether the clusters with low effective population sizes and potential inbreeding have changed their levels of genetic diversity in the intervening 6 years with management to increase cactus scrub and improve connectivity, from translocating wrens between genetic clusters, or from population declines during a long and intense drought. | in progress | |
| RES-2 | Analyze genetic and reproduction data from Orange County and San Diego County studies to determine if reproduction may be adversely affected by inbreeding or low genetic diversity. If lack of genetic diversity and inbreeding show signs of depressing productivity, then evaluate and prioritize specific management recommendations to increase gene flow, such as switching eggs or translocating individuals between genetic clusters over the short term and restoring habitat to expand populations and improve connectivity within and between genetic clusters over the long term. | in progress | |
| RES-3 | Submit project metadata, datasets, analyses, and report with specific management recommendations to the MSP Web Portal. | in progress |
| Criteria | Deadline year |
|---|---|
| Genetic Study Completed and Report Submitted by 2020 | 2021 |
| Threat Name | Threat Code |
|---|---|
| Altered fire regime | ALTFIR |
| Climate change | CLICHN |
| Loss of connectivity | LOSCON |
Management units: 2, 3, 4, 6
From 2017-2021, continue operation of the North San Diego County Cactus Nursery and support a South San Diego County Cactus Nursery to supply cactus to land managers to enhance, restore and create coastal cactus wren habitat. Grow cactus pads, segments and entire plants sufficient for restoration projects to expand and enhance cactus scrub habitat and as a source of plants for immediate habitat rehabilitation following severe wildfire.
| Action | Statement | Action status | Projects |
|---|---|---|---|
| IMP-1 | Implement BMPs when harvesting and growing cactus at a nursery in preparation for transplant into natural lands for cactus restoration projects and to provide an emergency source of cactus following wildfire. | some occurrences are in progress | North County Cactus Nursery and Coastal Cactus Wren Habitat Restoration (2015-2018) |
| IMP-2 | Grow and supply cactus pads, segments, and entire plants from locally harvested native cactus with a composition of species reflecting what naturally occurs in each geographic area. The North County Cactus Nursery should cactus to projects in MUs 6 and 8 and those areas in MU 4 dominated by prickly pear cactus. The South County Cactus Nursery should supply cactus to MUs 2 and 3 and to those areas in MU 4 dominated by coast cholla. The amount of cactus produced will be determined periodically based upon: management recommendations from the 2015 South San Diego County Coastal Cactus Wren Habitat Conservation and Management Plan; from ICR's Restoration Analyses for the San Pasqual Valley and Lake Hodges; an evaluation of planned and ongoing cactus restoration projects; and an assessment of cactus needed to be kept in reserve for future post-fire rehabilitation efforts. | some occurrences are in progress | North County Cactus Nursery and Coastal Cactus Wren Habitat Restoration (2015-2018) |
| IMP-3 | Submit project metadata, nursery plans, and reports with information on harvesting, growing and distributing cactus for restoration projects to the MSP Web Portal. | some occurrences are in progress | North County Cactus Nursery and Coastal Cactus Wren Habitat Restoration (2015-2018) |
| Criteria | Deadline year |
|---|---|
| Cactus Nurseries Established in North and South San Diego County to Provide Sufficient Cactus for Restoration and PostFire Rehabilitation | 2021 |
| Threat Name | Threat Code |
|---|---|
| Altered fire regime | ALTFIR |
| Climate change | CLICHN |
| Invasive plants | INVPLA |
| Loss of connectivity | LOSCON |
| Urban development | URBDEV |
Management units: 5, 6
In 2017-2021, continue supporting restoration of cactus scrub based upon ICR's Restoration Analyses for the San Pasqual Valley/Lake Hodges coastal cactus wren genetic cluster (see occurrence table) to: rehabilitate cactus scrub destroyed or degraded by the 2007 Witch Fire; to expand occurrences, particularly adjacent to Lake Hodges; to improve connectivity within the genetic cluster; and as needed, to manage high risk of anthropogenic predation of adults and nestlings.
| Action | Statement | Action status | Projects |
|---|---|---|---|
| IMP-1 | Following best practices, design cactus scrub enhancement and restoration projects to provide high quality nesting and foraging habitat with large patches of cacti >1 m tall in a mosaic of open scrub that provides sufficient food resources for reproduction and survival, especially during drought years when arthropod food resources are limiting. As they become available, incoporate the results from the Cactus Wren Demography, Foraging and Arthropod Study to create restoration palettes that favor plant species associated wtih important wren food resources. Design planting layouts to maximize water availability by allocating a portion of the plantings to more mesic sites, such as ravines, at the bottom of slopes, and on northerly and easterly aspects. Control invasive nonnative plants to =20% absolute cover to reduce competition with native plants for water and light. | in progress | Hodges Reservoir-Bernardo Bay Cactus Wren Habitat Restoration Grant Project |
| IMP-2 | Implement management actions, as needed, to reduce anthropogenic predation on wrens and their nests in fragmented habitats bordered by development where wrens are vulnerable to predation by cats, Cooper's hawks, corvids and other human-subsidized predators. Actions could include removing selected trees within or bordering cactus scrub that provide hunting, roosting, and nesting perches for hawks and corvids and avoiding cactus scrub restoration in areas where the terrain and location make wrens especially vulnerable to predation. Other measures could involve humanely removing feral cats from Conserved Lands and providing educational material and signage encouraging neighboring homeowners to keep their cats indoors so that wrens are protected and cats are safe from predation by wild animals, such as coyotes. | in progress | Hodges Reservoir-Bernardo Bay Cactus Wren Habitat Restoration Grant Project |
| Criteria | Deadline year |
|---|---|
| By 2021, =2 High Priority Management Actions Implemented from ICR's Restoration Analyses for the San Pasqual Valley and Lake Hodges | 2021 |
| Threat Name | Threat Code |
|---|---|
| Altered fire regime | ALTFIR |
| Climate change | CLICHN |
| Invasive plants | INVPLA |
| Loss of connectivity | LOSCON |
| Urban development | URBDEV |
Management units: 5, 6
From 2017-2021, collect data on the effectiveness of implementing high priority management actions to restore cactus scrub to expand coastal cactus wren populations and enhance connectivity within the San Pasqual Valley/Lake Hodges genetic cluster (see occurrence table). In 2021, compile data from all restoration projects and determine the effectiveness of cumulative management actions for north San Diego County. Use these results to develop a management strategy that will provide the basis for preparing a North County Coastal Cactus Wren Habitat Conservation and Management Plan in 2022.
| Action | Statement | Action status | Projects |
|---|---|---|---|
| IMP-1 | Collect vegetation data to document success of cactus scrub restoration projects. This can include monitoring the height, diameter and survival of planted cactus and the composition and percent cover of native and nonnative shrubs, forbs and grasses. Document wren use of restored cactus scrub. | some occurrences are in progress | |
| IMP-2 | Submit restoration and enhancement project metadata, management datasets, and reports to the MSP Web Portal. | some occurrences are in progress | |
| IMP-3 | Conduct a meta-analysis of habitat restoration data and cactus wren population survey data to determine whether short-term success criteria have been achieved for habitat restoration actions and for wren populations in north San Diego County. Based upon these results, prepare recommendations for a 2022-2031 management strategy for coastal cactus wren. These broad recommendations can be used in 2022 to prepare a North San Diego County Coastal Cactus Wren Habitat Conservation and Management Plan with specific, prioritized management actions. | waiting for precedent action | |
| IMP-4 | Submit cactus wren habitat restoration and population meta-analysis datasets, results, and management strategy recommendations for north San Diego County to the MSP Web Portal. | waiting for precedent action |
| Criteria | Deadline year |
|---|---|
| Success Criteria 2013-2021: Restore =75 Acres of High Quality Cactus Scrub and Increase the San Pasqual Valley/Lake Hodges Genetic Cluster to =90 Territories on Conserve | 2021 |
| Threat Name | Threat Code |
|---|---|
| Altered fire regime | ALTFIR |
| Climate change | CLICHN |
| Herbivory/predation | |
| Invasive plants | INVPLA |
| Loss of connectivity | LOSCON |
| Urban development | URBDEV |
Management units: 2, 3, 4, 5, 6
Implement prefire management to reduce potential severity and impacts from future fire at prioritized cactus wren occurrences and habitats most at risk from wildfire.
| Action | Statement | Action status | Projects |
|---|---|---|---|
| IMP-1 | Implement management actions to reduce severity of potential fires through opening up dense cactus scrub habitats by trimming and thinning shrubs to maintain open scrub, maintaining bare ground buffers around large intact cactus patches, and by reducing nonnative grasses and herbs that can carry wildfire into cactus patches. Design management actions to avoid significant impacts to CSS vegetation or to other MSP species. | Available for implementation | |
| IMP-2 | As opportunities arise, implement management actions to reduce potential fire impacts in conjunction with other ongoing enhancement and restoration projects for cactus wrens. | Available for implementation | |
| IMP-3 | Submit project metadata and management actions to the MSP Web Portal. | Available for implementation |
| Criteria | Deadline year |
|---|---|
| By 2021, Implement =1 Management Action to Reduce Impacts from Future Fire at Prioritized Wren Occurrences | 2021 |
| Threat Name | Threat Code |
|---|---|
| Altered fire regime | ALTFIR |
| Invasive plants | INVPLA |
Management units: 2, 3, 4, 5, 6
For at least the first 3 years following a wildfire, use a standardized survey protocol to determine the status of coastal cactus wren occurrences affected by the wildfire. Use a standardized postfire protocol to collect vegetation and other covariates important in characterizing postfire cactus scrub habitat recovery. Collect habitat recovery data at unoccupied cactus scrub sites that are important for enhancing connectivity or for future population expansion. Identify and prioritize management actions to recover wren populations and important cactus scrub habitat patches.
| Action | Statement | Action status | Projects |
|---|---|---|---|
| IMP-1 | Prepare postfire habitat monitoring protocols and sampling design to determine the status of coastal cactus wrens and characterize cactus scrub recovery following wildfire. Use the monitoring results to identify management actions to ensure postfire recovery of high quality cactus scrub at occupied cactus wren sites and at unoccupied cactus scrub sites important for wren population expansion and connectivity within and between genetic clusters. | On hold | |
| IMP-2 | Submit project metadata, cactus wren postfire survey and habitat monitoring data, annual reports with management recommendations, and a final report documenting project methods and results to the MSP Web Portal. | On hold |
| Criteria | Deadline year |
|---|---|
| At Least 3 Years of Postfire Monitoring of Cactus Wrens and Habitats with Annual Management Recommendations | 2021 |
| Threat Name | Threat Code |
|---|---|
| Altered fire regime | ALTFIR |
| Invasive plants | INVPLA |
| Loss of connectivity | LOSCON |
Management units: 2, 3, 4, 5, 6
For at least the first 3 years following a wildfire, implement management actions identified by postfire monitoring as necessary to protect and rehabilitate high quality cactus scrub to allow for recovery of coastal cactus wren occurrences affected by the wildfire.
| Action | Statement | Action status | Projects |
|---|---|---|---|
| IMP-1 | Implement management actions to restore cactus scrub habitat destroyed by wildfire. These management actions may include planting large >1m cactus to create nesting and roosting habitat for immediate postfire use by cactus wrens, planting pads and segments to improve habitat over the longer term, and to seed or plant native shrubs and forbs as needed to enhance habitat suitability and increase available arthropod food resources (use recommendations from the Coastal Cactus Wren Demography, Vegetation and Arthropod Study). Control invasive nonnative plants to =20% absolute cover to reduce postfire invasion of nonnative plants and to allow postfire recovery of native plants by reducing competition for water and light. Control erosion and human use impacts while habitat is recoverying. | On hold | |
| IMP-2 | Submit project metadata and management actions to the MSP Web Portal. | On hold |
| Criteria | Deadline year |
|---|---|
| At Least 3 Years of Postfire Management in Priority Cactus Wren Habitats | 2021 |
| Threat Name | Threat Code |
|---|---|
| Altered fire regime | ALTFIR |
| Altered hydrology | ALTHYD |
| Invasive plants | INVPLA |
| Metric | Condition | Trend | Confidence |
|---|---|---|---|
1. Occupied PlotsPercent of survey plots on conserved lands with coastal cactus wren detections |
Caution |
No Change |
High |
2. Habitat QualityPercent of survey plots impacted by one or more threats |
Concern |
No Change |
High |
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Bernardo Mountain Post-Fire Habitat Recovery Project
Bernardo Mountain is located north of Lake Hodges, west of I-15. The primary goal of this habitat conservation project is to protect the habitat of the federally listed coastal California gnatcatcher, as well as other listed and sensitive animal species such as coastal cactus wren and sensitive plant and wildlife species that are covered under the Multiple Habitat Conservation Plan ("MHCP").
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Cactus Wren Genetic Analysis - Historical Museum Samples
The purpose of this study is to gather genetic data from museum samples collected in the early 1900s to compare levels of genetic diversity and population structure to present day estimates. From this analysis, USGS hopes to determine whether there has been an increase in population genetic differentiation and a loss of genetic diversity in Southern California Cactus Wrens over the past century, and to quantify these changes. Results will help inform potential management actions such as choosing source populations for re-establishment and augmentation.
This project will consist of the following objectives:1) Develop protocols for DNA extraction and amplification of historical museum samples for microsatellite loci; 2) Travel to museums in California to retrieve tissue from relevant museum specimens; 3) Genotype samples, analyze patterns of genetic differentiation and diversity, and prepare a report comparing past to present population genetic structure.
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Cactus Wren Genetic Study - Regional
This study analyzes genetic population structure in the cactus wren throughout coastal southern California using microsatellite markers developed specifically for this species. It expands upon a previous study focused in Orange and San Diego Counties (Barr et al. 2012), adding cactus wren samples from Ventura, Los Angeles, San Bernardino, and Riverside Counties. Additional samples from Palos Verdes and West Coyote Hills were included in the original dataset in an addendum to the study. With this full dataset, we characterize the current population genetic structure to provide information on levels of gene flow throughout the cactus wren’s range in coastal southern California. We also analyze genetic diversity and recent demographic change over the study area. Understanding these patterns will aid in management of current cactus wren populations and future efforts in habitat restoration.
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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.
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Cactus Wren Habitat Conservation and Management Plan
The Cactus Wren Habitat Conservation and Management Plan has been prepared to help fulfill MSP Goals and Objectives established for management of the Coastal Cactus Wren in MU3. This plan identifies and prioritizes management and restoration needs for the cactus wren across the entire MU3, and also assesses connectivity to core habitat areas on Conserved Lands within the San Diego/El Cajon cactus wren genetic cluster in MUs 2 and 4 to further ensure persistence of the cactus wren in MU3 over the next 100 years.
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Cactus Wren Habitat Restoration
Brief synopsis of our cactus scrub restoration methodology:
1. Selected proposed restoration areas that were CSS pre-Harris fire, on south or southwest-facing slopes, in San Miguel Exchequer rocky silt loam. Polygons totaled 50 ha. Essentially
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Cactus Wren Monitoring in southern San Diego County
This is a planned 5-year study with two main goals: 1) Assess the population status of the coastal cactus wren following the 2014 drought and 2) monitor the implementation of the MSP 2015 Habitat Conservation and management Plan's highest priority management actions. In the first year, the population status of cactus wren in MUs 3 and 4 was assessed to determine the relationship between habitat quality, food availability, and cactus wren productivity and survival. In 2017, the focus is on monitoring cactus wren reproduction and survival and conducting vegetation sampling. Specific management recommendations will be developed to respond to short-term emergency needs and to enhance habitat for long-term cactus wren persistence. Continued monitoring will be done annually.
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Cactus Wren Occupancy Study and Cactus Patch Mapping
Given the extent and severity of the 2003 and 2007 wildfires in San Diego County there is an increase cause for concern in understanding the amount of available habitat and the percent of that habitat that is occupied by the coastal cactus wren. The USFWS has developed and refined a protocol for conducting coastal cactus wren monitoring. USFWS tested the protocol by completing surveys in 2009 and 2010. All southwest and southeast facing slopes below 1,500 feet, within San Diego MSCP preserve lands, were mapped for the occurrence of cactus patches. Once cactus patches were mapped in GIS, these patches were segmented into plots and surveyed for cactus wrens.
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Chula Vista Cactus Wren Habitat Restoration and Enhancement Program
A 5-year restoration and enhancement project designed to maintain and increase suitable habitat for the cactus wren in the City of Chula Vista's Central City Preserve. The goal of this program is to ensure the prolongation of the coastal cactus wren through active management of suitable cactus wren habitat, restore degraded and/or fragmented cholla patches, and initiate activities to reduce edge effects associated with invasive species, uncontrolled access and risk of fire.
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Coastal Cactus Wren Conservation Network
The Coastal Cactus Wren Conservation Network is an ad hoc group of more than 100 individuals representing research institutions, land management agencies, local government, non-profit conservation organizations and wildlife agencies. Members work together to exchange research and management information to develop best practices, policies, and programs that promote conservation and recovery of this bird throughout its range (Ventura, Los Angeles, San Bernardino, Orange, Riverside, and San Diego counties). This information will inform publication of a regional conservation strategy for the coastal cactus wren.
Cactus wrens (Campylorhynchus brunneicapillus) are distributed across the arid regions of the southwestern United States and northern and central Mexico (Hamilton et al. 2011). While the desert populations are fairly abundant, populations of coastal cactus wrens have declined dramatically over the past 30 years, with extirpation and genetic isolation affecting many locations as a result of habitat loss, habitat fragmentation, edge effects of development, and catastrophic fires (Solek and Szijj 2004). The coastal population is unique in that it occurs exclusively within the coastal sage scrub plant community, ranging from Ventura County south into San Diego County, U.S.A. and northwestern Baja California, Mexico. The firestorms of 2007 impacted several strongholds for the coastal cactus wren in Orange and San Diego counties. The significant loss of habitat and birds was the impetus for formation of the Coastal Cactus Wren Network.
For more information on the Coastal Cactus Wren Conservation Network, please see the document titled "Coastal Cactus Wren Working Group Regional Goals, Objectives, and Strategies".
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Hodges Reservoir-Bernardo Bay Cactus Wren Habitat Restoration Grant Project
This project restored habitat for the California Species of Special Concern, the coastal cactus wren (Campylorhynchus brunneicapillus), near the Hodges Reservoir-Bernardo Bay. This included a 20 acre restoration of cactus burned in the 2007 Witch Creek Fire. Additionally, unauthorized trails were closed off and the soil was stabilized to minimize erosion and filter runoff into source water reservoir. The purpose of this restoration project was to re-establish cactus wren habitat and connectivity to eastern core habitat areas.
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Lusardi Creek Restoration and Invasive Plant Removal
This project is working to eradicate invasive species and support native plants along Lusardi Creek. Many areas have already been treated and are recruiting natives naturally. Other areas are being planted with natives after invasive plant removal. The current goals include: 1) treat artichoke in several upland areas, 2) continue removing tamarix in the creek, 3) treat any regrowing Peruvian pepper, 4) treat any remaining pampas grass or tree tobacco, 5) work on an overall restoration plan. See the map link below for detailed treatment information.
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Otay River Valley Cactus Wren Habitat Restoration and Enhancement
The goal of this three-year project (#5004730) is to increase the amount of suitable habitat and improve connectivity for the coastal cactus wren along Otay River Valley through restoration and enhancement of degraded habitat areas. This project will complement the existing coastal cactus wren habitat restoration project proposed by the City of Chula Vista within the Otay River Valley and Salt Creek as part of the current Transnet EMP grant cycle. The coastal cactus wren restoration program in the Otay River Valley and Salt Creek area address the immediate needs of the coastal cactus wren where loss and degradation of existing wren habitat has occurred due to historical cattle grazing, increase of invasive plant species, unauthorized off-road vehicle use, drought, and vegetation succession processes. Activities included in this program include invasive species control with follow-up herbicide treatments, shrub thinning, collecting and planting coast cholla and coast prickly pear cuttings, native grass and forb seed collection and redistribution, vegetation monitoring, and focus cactus wren monitoring. An additional grant (#5004944) was awarded the first year of project implementation that provided access control fencing to the #5004730 project. Activities for the proposed project include the installation of t-post barbless wire fencing around the 3.5 acre CACW restoration area, in addition to installing 8 signs stating "Habitat Restoration Area - No Trespassing." This project would fulfill the immediate need for access control to the CACW restoration area, deterring off-road vehicles, bikers, equestrians, and other trails users from entering the project site. By providing funding for access control to this restoration and enhancement site, it will increase the success of EMP Grant #5004730.
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Salt Creek Coastal Cactus Wren Habitat Restoration Project
The goal of the project was to enhance, restore, expand, and monitor coastal cactus wren habitat in the Salt Creek area. In 2008, County of San Diego County Department of Parks and Recreation planted 7,000 to 10,000 cactus cuttings toenhance and improve existing coastal cactus wrenhabitat on 1.4 acres within the Otay Ranch Preserve inthe Salt Creek area. The area is jointly managed by theCounty and City of Chula Vista. Monitoring of birds and vegetation was conducted.
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San Pasqual Habitat Restoration and Cactus Nursery Project
Provide habitat connectivity between Lake Hodges and the Safari Park for cactus wren expansion and establish a cactus nursery in North County for habitat restoration for cactus wren. This is an on-going project that has multiple funding sources.
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Resident species from S. Calif. south to S. Baja Calif., S. Nevada, SW Utah, W. and south central Arizona, S. New Mexico, and central Texas south to Mexico [1].
In San Diego County, the coastal cactus wren is known to occur at Lake Hodges/San Pasqual Valley, Lake Jennings, South Sweetwater Reservoir/San Miguel Ranch, and Salt Creek/Otay Mesa, Camp Pendleton/ Fallbrook NWS; San Pasqual Valley and Lake Hodges; San Diego and El Cajon; and Otay River [3, 4].
CSC
Closely associated with three species of cacti and occurs almost exclusively in thickets of cholla (Opuntia prolifera) and prickly pear (Opuntia littoralis and Opuntia oricola) dominated stands of coastal sage scrub below 457 meters in elevation on mesas and lower slopes of the coast ranges [2].
Eight subspecies are recognized with the subspecies falling into roughly two groups the affinis group (peninsular forms) and brunneicapillus group (continental forms) [2]. Recent USGS genetic studies showed genetic differentiation between four distinct genetic clusters: Orange County and MCB Camp Pendleton/ Fallbrook NWS; San Pasqual Valley and Lake Hodges; San Diego and El Cajon; and Otay River [3, 4].
Exhibits year-long, diurnal activity. The species is not migratory [5].
Breeds from March into June; clutch size is 4-5 eggs, with a range of 3-7 eggs [6]. Two broods per season are common; incubation is 15-18 days, by the female only [7]. The altricial nestlings fledge at 17-23 days, with an average of 21 [8]. The young may return to roost in the nest after fledging. The young become independent at about 1 mo after leaving the nest; sometimes the young help feed the young of later broods [6]. Overall adult survival rate reported as 50.6% during a six year study [7].
Forages on the ground and in low vegetation for insects and other small invertebrates, cactus fruits and other fruits, seeds and nectar [7, 9]. Fruits make up 15-20 percent of the annual diet [10].
Generally considered to have low dispersal; in Arizona, of 55 nestlings banded, 41 dispersed from the natal site by 45 days postfledging; males remain near the natal site, usually dispersing only as far as parental territorial behavior dictated [2].
The most important threat to coastal cactus wren has been the loss and fragmentation of cactus scrub habitat as a result of urban and agricultural development [2]. A second primary threat is large wildfires that cause direct mortality of birds and destroy cactus scrub, which can take many years to recover [11, 12, 13, 14].Other threats include invasive plant species reducing open habitat for foraging, [15, 16] declines in productivity during drought, and predation by domestic cats, roadrunners, snakes, loggerhead shrikes, and especially Cooper's hawks.
[0] 1. Terres, J. K. 1980. The Audubon Society Encyclopedia of North American Birds. Alfred A. Knopf, New York, New York. 1109pp. 2. Proudfoot, G. A. , D. A. Sherry, and S. Johnson. 2000. Cactus wren (Campylorhynchus brunneicapillus) No. 558. In The Birds of North America, A. Poole and F. Gill, Eds. Cornell laboratory of Ornithology, New York, and The Academy of Natural Sciences, Washington D.C.3. Barr, Kelly R., Amy G. Vandergast and Barbara E. Kus. 2012. Genetic Connectivity in the Coastal Cactus Wren. Data summary report prepared for the San Diego Management and Monitoring Program and the San Diego Association of Governments (SANDAG). 4. Barr, Kelly R., Amy G. Vandergast, and Barbara E. Kus. 2013. Genetic Structure in the Cactus Wren in Coastal Southern California. Data summary report prepared for the California Department of Fish and Wildlife. 5. Zeiner, D. C., W., F. Laudenslayer, Jr., K. E. Mayer, M. White. Editors. 1990. California's Wildlife. Volume 2. Birds. State of California, Department of Fish and Game. Sacramento, California. 731 pp. 6. Harrison, C. 1978. A field guide to the nests, eggs and nestlings of north American birds. W. Collins Sons and Co., Cleveland, OH. 416pp. 7. Anderson, A. H., and A. Anderson. 1960. Life history of the cactus wren. Part III: The nesting cycle. Condor 62:351-369. 8. Hensley, M. M. 1959. Notes on the nesting of selected species of birds of the Sonoran Desert. Wilson Bull. 71:86-92. 9. Bent, A.C. 1968. Life histories of North American Nuthatches, Wrens, Thrashers, and their allies. U.S. National Museum Bulletin 195. U.S. Government Printing Office. Washington, D.C. 10. Ehrlich, P. R., D. S. Dobkin, and D. Wheye. 1988. The birder's handbook. Simon and Schuster, New York. 785pp. 11. Bontrager, D. R., R. A. Erickson, and R. A. Hamilton. 1995. Impacts of the October 1993 Laguna Canyon fire on California Gnatcatchers and Cactus Wrens. Pp. 69-76 In Brushfires in California wildlands: ecology and resource management (J. E. Keeley and T. Scott, eds.). Int. Assoc. Wildland fire, Fairfield, WA. 12. Mitrovich, Milan J. and Robert A. Hamilton. 2007. Status of the Cactus Wren (Campylorhynchus brunneicapillus) within the Coastal Subregion of Orange County, California. Prepared for the Nature Reserve of Orange County. 13. Hamilton, Robert A. 2008. 2008 Surveys Cactus Wrens and California Gnatcatchers San Dieguito River Valley, San Diego County. Report prepared for Conservation Biology Institute. 14. Leatherman BioConsulting, Inc. 2009. Central Reserve Cactus Wren Habitat Assessment and Study 2008. Prepared for the Nature Reserve of Orange County. 15. Preston, Kristine L. and Dana Kamada. 2012a. Nature Reserve of Orange County: Monitoring Coastal Cactus Wren Reproduction, Dispersal and Survival, 2009-2011. Report prepared for California Department of Fish and Game, Local Assistance Grant #PO982013. 16. Kamada, Dana and Kristine Preston. 2013. Nature Reserve of Orange County: Coastal Cactus Wren Dispersal and Survival Surveys, Genetics and Parasite Sampling, and Arthropod Foraging Ecology in 2012. Annual Memorandum of Understanding report prepared for California Department of Fish and Wildlife.