The coastal cactus wren (Campylorhynchus brunneicapillus couesi) is a California
Species of Special Concern and the coastal California gnatcatcher (Polioptila californica
californica) is a federally listed threatened species. Both are target species under California’s
Natural Communities Conservation Program. Habitat loss is the driving force for population
decline of both species. This study examines these target species on part of Marine Corps
Base Camp Pendleton, California (approximately 41, 118 hectares in area). The purpose of
this research is to delineate the local geography for each species and to demonstrate a
geographic approach to avian conservation.
This study defines the local geography as a combination of the landscape
characteristics, specific habitat requirements, and the identification of core habitat areas for
both species. Landscape characteristics refer to the composition and spatial configuration of
the vegetation on the Base. Landscape characteristics have been obtained through landscape
metric calculations. Specific habitat requirements refer to the habitat features that shape the
spatial distribution of both species. Habitat requirements have been obtained through habitat
suitability analysis and species distribution modeling. Core habitat areas reflect the landscape
characteristics and the habitat features that sustain both avian populations. Lastly, core
habitat areas have been identified via kernel density estimation and prioritized by a set of
detailed criteria based on requirements for both species on the Base. This study provides
information regarding habitat requirements of both species and overall landscape
characteristics on the Base, which will aid in conservation and management of these species.
On a broad scale, this research supports the regional conservation effort in southern
California for the coastal cactus wren and the coastal California gnatcatcher.
Adaptive management is an approach to problem solving that acknowledges uncertainty.
Adaptive management involves a systematic and rigorous process of learning from the
outcomes of management actions, accommodating change and improving management.
Plans, policies or management strategies influenced by new information and learning, are
modified.
This study examines the implementation of adaptive management for endangered and
threatened species covered in Habitat Conservation Plans (HCP). Introduced in 1982 as
an amendment to the Endangered Species Act (ESA), Habitat Conservation Plans are
negotiated agreements that mitigate the incidental “take†(killing, harming) of
endangered and threatened species during a development or resource extraction project.
However, scholars found the scientific basis of approved HCPs to be inadequate and the
efficacy of prescribed mitigation measures untested implying the need for adaptive
management during implementation.
This case study evaluation investigates HCP landowner compliance and progress within
the parameters of the federal 1994 “No Surprises†policy. That policy limits landowner
liability and responsibility for additional conservation action due to failed mitigation
measures during HCP implementation. “No Surprises†assumes we can predict all the
consequences of implementing a HCP. The policy seems to work against the objectives
of adaptive management to improve scientific knowledge and modify action. The cases
include the Central Cascades HCP implemented in the Central Cascades of Washington
and the Orange Central Coastal County HCP implemented within a nature reserve in
Orange County, California. The study assesses the strengths and weaknesses of adaptive
management implementation in protecting endangered species and their habitat, and 2)
recommends mid-course corrections for improving adaptive management before HCP
maturity.
The Cactus Wren (Campylorhynchus brunneicapillus: Troglodytidae), a highly
sedentary, nonmigratory bird is distributed among cactus-dominated habitats of the
southwest United States and Mexico, including coastal Southern California. The coastal
populations are waning and conservation efforts have been enacted to slow the decline of
the coastal populations. A paucity of genetic information related to the Cactus Wren has
led this study to test for genetic differentiation between coastal and inland birds. This
study examined two regions of mtDNA sequences for haplotype variation in 136
individuals in 18 populations from Southern California, Arizona, Texas, and Mexico.
There were seven haplotypes for CytB, seven for ND2, and nine for a coastal subset of
ND2. There was a significant relationship between genetic and geographical distance
within the coastal populations but no significant genetic differentiation between coastal
and inland desert Cactus Wren found in this study.
Abstract- A new method of measuring reproductive success is proposed that uses a
composite of breeding-behavior observations (for behaviors that reflect different stages in
the reproductive cycle) as an index of fitness. This reproductive index does not rely on
discovery of nests, but is comprehensive in that it includes information on all monitored
territories. The reproductive index was applied to three co-occurring emberizine
sparrows, two of which required special care because of their regional rarity. Ranks
derived from this reproductive index were used to distinguish territories of birds of
known high success (i.e., those that fledged young in at least one brood) from territories
of birds with known low success (unpaired males), and were compared with findings for
“spot-mapped†territories. Principal components analyses of habitat measurements for
these territory types revealed a similar pattern for all three species: spot-mapped
territories overlapped broadly with nonterritory (unoccupied) plots, whereas high-success
territories formed a discrete isolated cluster within the spot-map matrix. Univariate
analyses revealed that high success territories were described by 15 vegetation features
that differed (p <.01) from nonterritory values, whereas in spot mapped territories, only 8
vegetation variables differed and in low success territories only 2 differed. The ability to
distinguish high success territories allowed us to identify a greater number of habitat
features that were correlated with reproductive success. If we had relied on spot mapping
method, we would have been unable to identify many of these important habitat features.
Yet the ability to make such discriminations is likely to be critical in the management of
threatened species.
Habitat loss and fragmentation can lead to smaller and more isolated populations and reduce genetic diversity and evolutionary potential. Conservation programs can benefit from including monitoring of genetic factors in fragmented
populations to help inform restoration and management. We assessed genetic
diversity and structure among four major populations of the Cactus Wren (Campylorhynchus brunneicapillus) in San Diego County in 2011–2012 and again in
2017–2019, using 22 microsatellite loci. We found a significant decline in heterozygosity in one population (San Pasqual) and a decline in allelic richness and
effective population size in another (Sweetwater). Genetic diversity in the
remaining two populations was not significantly different over time. Local diversity declined despite evidence of dispersal among some populations. Approximately 12% of genetically determined family groups (parents, offspring, siblings)
included one or more members sampled in different territories with distances
ranging from 0.2 to 10 km. All but one inferred dispersal events occurred within
the same genetic population. Population structure remained relatively stable,
although genetic differentiation tended to increase in the later sampling period.
Simulations suggest that at currently estimated effective sizes, populations of
Cactus Wrens will continue to lose genetic diversity for many generations, even
if gene flow among them is enhanced. However, the rate of loss of heterozygosity could be reduced with increased gene flow. Habitat restoration may help bolster local population sizes and allelic richness over the long term, whereas
translocation efforts from source populations outside of San Diego may be
needed to restore genetic diversity in the short term.
Conservation management under human-induced changes to disturbance requires tools that can balancethe needs of multiple species with different life histories and habitat requirements. Despite this urgentconservation need, landscape management typically focuses on single species and rarely includes theinfluence of disturbance-dependent vegetation transitions on multiple target species. In this paper, wedescribe a simulation model that achieves these goals, ranking possible fire management strategies fromthe viewpoint of protecting endangered coastal Southern Californian wildlife. The model involves thedirect and indirect effects of fire on four animal species of conservation concern (coastal cactus wren,California gnatcatcher, Stephens’ kangaroo rat, and Pacific pocket mouse) and five vegetation types (grass,coastal sage scrub, obligate seeding and resprouting chaparral, resprouting-only chaparral, and wood-lands). Using historical fire records for the region, we predicted spatially-explicit fire frequencies andignition probabilities. For these predictions, we simulated the location and extent of fires. Combining firehistory and vegetation transition data from 1933 to 2003, we specified vegetation change probabilitiesunder simulated fire regimes. Fire occurrence in a location altered habitat suitability, directly for each ofthe animal species and indirectly by changing the vegetative community. For some open-habitat species,such as the Stephens’ kangaroo rat and Pacific pocket mouse, fairly frequent fire is required to reduce thedensity of invasive grasses and herbs. For other species, such as the coastal cactus wren and Californiagnatcatcher, frequent fire destroys the mature coastal sage scrub on which these species depend. Themodel includes a management component, allowing us to rank fire management actions. Over a 50-yeartime horizon, we find that populations of California gnatcatchers and Pacific pocket mouse are highlyvariable, and the pocket mouse is particularly prone to decline, despite prescribed burns designed toboost population viability. California gnatcatchers were also likely to be extirpated in the model, withrelatively small extirpation risks for the cactus wren and Stephens’ kangaroo rat. Despite conflictingrequirements with respect to fire and differing life history traits among the four animals, we identified abeneficial strategy for our four target species, namely, controlling fire in coastal sage scrub.
Changes in the distribution and abundance of bird and small mammal species at
urban-wildland edges can be caused by different factors. Edges can affect populations
directly if animals respond behaviorally to the edge itself or if proximity to edge
directly affects demographic vital rates (an ‘‘ecotonal’’ effect). Alternatively, urban
edges can indirectly affect populations if edges alter the characteristics of the adjacent
wildland vegetation, which in turn prompts a response to the altered habitat (a
‘‘matrix’’ or ‘‘habitat’’ effect). We studied edge effects of birds and small mammals in
southern Californian coastal sage scrub, and assessed whether edge effects were
attributable to direct behavioral responses to edges or to animal responses to changes
in habitat at edges. Vegetation species composition and structure varied with distance
from edge, but the differences varied among study sites. Because vegetation characteristics
were correlated with distance from edge, responses to habitat were explored
by using independently-derived models of habitat associations to calibrate vegetation
measurements to the habitat affinities of each animal species. Of sixteen species
examined, five bird and one small mammal species responded to edge independently
of habitat features, and thus habitat restoration at edges is expected to be an
ineffective conservation measure for these species. Two additional species of birds
and one small mammal responded to habitat gradients that coincided with distance
from edge, such that the effect of edge on these species was expressed via potentially
reversible habitat degradation.
We compared mitochondrial DNA sequences for six species distributed across the
aridlands of North America to document phylogeographic patterns and assess levels of congru-
ence. The Curve-billed Thrasher (Toxostoma curvirostre) and Canyon Towhee (Pipilo fuscus)
show genetic divisions between the Sonoran and Chihuahuan Deserts, whereas the Cactus Wren
(Campylorhynchus brunneicapillus), Black-tailed Gnatcatcher (Polioptila melanura), and Verdin
(Auriparus flaviceps) do not. Most likely, species without phylogeographic structure only recently
colonized their entire current range. Therefore, although these species are today part of a wide-
spread avifauna, species’ distributions were historically different from today. In Baja California,
the Cactus Wren and the Verdin show phylogeographic breaks at 288–308N, consistent with a
division previously described in the LeConte’s Thrasher (Toxostoma lecontei) and in some mem-
bers of the herpetofauna. These genetic divisions were likely caused by isolation resulting from
a mid-peninsular seaway that existed one million years ago. Hence, these species appear to have
been broadly sympatric for at least one million years. In contrast, the California Gnatcatcher
(Polioptila californica) lacks such a phylogeographic division, and apparently only recently
expanded into the northern part of its current range. Thus, not all species in Baja California have
had similar histories, although further sampling might reveal a general pattern. Comparative
phylogeography therefore provides an indirect method of evaluating the long-term stability of
faunas via assessment of levels of phylogeographic congruence, and can show whether particular
species are likely to have had a long period of co-association.
The Cactus Wren (Campylorhynchus brunneicapillus) is a polytypic
species widespread in the southwestern U.S. and northern Mexico. Though closer
in plumage characteristics to the desert subspecies anthonyi, populations resident in
coastal sage scrub on the coastal slope of Ventura County and Los Angeles County
occupy an ecological niche more similar to that of the more southerly subspecies
sandiegensis. Because of fragmentation of habitat associated with urbanization, the
populations on southern California’s coastal slope are almost entirely isolated from
those of the deserts, and apparently from each other. They are declining precipitously
for reasons not entirely understood but certainly related to loss, fragmentation, and
degradation of suitable habitat. In 2012, we organized a volunteer effort to map the
entire population in Ventura County and found 111 active, accessible territories with
at least one adult or a fresh nest. Additional areas to which we did not have access
could raise this total number to 166 territories county-wide. While historically the
species occurred somewhat more widely in the eastern portion of the county, all
active territories now appear to be restricted to a narrow band of cactus-rich scrub
at the far western edge of the Santa Monica Mountains and Simi Hills, from Point
Mugu northeast through Thousand Oaks to the west side of Simi Valley, roughly
tracking the distribution of large patches of prickly-pear (Opuntia spp.) and coast
cholla (Cylindropuntia prolifera).
Subspecies are often used in ways that require their evolutionary independence, for example as proxies
for units of conservation. Mitochondrial DNA sequence data reveal that 97% of continentally distributed
avian subspecies lack the population genetic structure indicative of a distinct evolutionary unit. Subspecies
considered threatened or endangered, some of which have been targets of expensive restoration efforts,
also generally lack genetic distinctiveness. Although sequence data show that species include 1.9 histori-
cally significant units on average, these units are not reflected by current subspecies nomenclature. Yet,
it is these unnamed units and not named subspecies that should play a major role in guiding conservation
efforts and in identifying biological diversity. Thus, a massive reorganization of classifications is required
so that the lowest ranks, be they species or subspecies, reflect evolutionary diversity. Until such reorganiza-
tion is accomplished, the subspecies rank will continue to hinder progress in taxonomy, evolutionary
studies and especially conservation.
The delimitation of populations, defined as groups of individuals linked by gene flow, is
possible by the analysis of genetic markers and also by spatial models based on dispersal
probabilities across a landscape. We combined these two complimentary methods to define
the spatial pattern of genetic structure among remaining populations of the threatened
Florida scrub-jay, a species for which dispersal ability is unusually well-characterized. The
range-wide population was intensively censused in the 1990s, and a metapopulation model
defined population boundaries based on predicted dispersal-mediated demographic
connectivity. We subjected genotypes from more than 1000 individual jays screened at 20
microsatellite loci to two Bayesian clustering methods. We describe a consensus method for
identifying common features across many replicated clustering runs. Ten genetically
differentiated groups exist across the present-day range of the Florida scrub-jay. These groups
are largely consistent with the dispersal-defined metapopulations, which assume very
limited dispersal ability. Some genetic groups comprise more than one metapopulation,
likely because these genetically similar metapopulations were sundered only recently
by habitat alteration. The combined reconstructions of population structure based on
genetics and dispersal-mediated demographic connectivity provide a robust depiction of
the current genetic and demographic organization of this species, reflecting past and
present levels of dispersal among occupied habitat patches. The differentiation of populations
into 10 genetic groups adds urgency to management efforts aimed at preserving what
remains of genetic variation in this dwindling species, by maintaining viable populations
of all genetically differentiated and geographically isolated populations.
Vegetation transects performed at four separate occupied sites in eastern Los Angeles County indicated a relationship between cactus height and nesting desirability and a potential relationship between cactus patch size and corresponding nest height
Goals:
Synthesize available information to assess current status and trends.
Identify information gaps most relevant to informing strategies for effective conservation
management
Identify priority monitoring and research questions; secure collaborations and catalyze
investigations.
Identify and prioritize options for management.
Focus habitat protection efforts and initiate controlled experimentation in restoration.
In 2021, Opuntia littoralis (Coastal prickly-pear) plants at a restoration nursery in San Diego County were observed with circular yellow, red, and gray dry lesions surrounding their spines
In 2022, further field surveys across 10 restoration sites in San Diego County showed affected plants with similar decay symptoms, at 5-25% prevalence
Cacti decay observed in restoration nurseries and in native habitats created concern about pathogen introductions into ecosystems that support coastal cactus wrens (a species of concern in CA)
Our local cholla and prickly pear cactus are generally easy to grow, but reducing the amount of handling and not potting them up makes budgets go much farther. Just putting out cuttings in the fall-winter rainy season and letting the rains do the work is the cheapest way to get good results. Based on our experience, small one stem cutting takes about 6-8 years to grow to around three feet without supplemental water, but growth will vary depending on soil conditions and annual rainfall patterns. If you do direct planting of cuttings and then water them at the intended habitat site, they will grow even faster.
Presentation from 2008 Coastal Cactus Wren Conservation Symposium on the status and distribution of coastal cactus wren in northern inland San Diego County
In 2006 and 2007, I developed methods in conjunction with Milan Mitrovich, then of the
Nature Reserve of Orange County (NROC), and Will Miller of the U.S. Fish & Wildlife
Service (USFWS) to map and characterize cactus resources in and around the NROC’s
coastal reserve, and to survey for Cactus Wrens in areas judged to comprise potentially
suitable nesting habitat. For the current volunteer-based effort, playback of digital
recordings of Cactus Wrens will not be allowed by the California Department of Fish &
Game, so the methods have been modified accordingly.
In addition to mapping the boundaries of cactus scrub, these methods identify different
types of scrub and document habitat composition at each site, thereby allowing reserve
managers to build models of habitat suitability for the Cactus Wren by correlating the
species’ presence with relevant habitat features.
This 2013 Wildland Fire Workshop focused on Southern California and landscape level fires occurring in the last decade. This workshop brought together land managers, researchers, and fire management personnel to continue the discussions on the topic of wildland fire impacts to at risk natural resources. The purpose of the workshop was to present, collaborate, and plan wildland fire-related research, management, responses, and future recovery as it applies to the “at risk†natural resources of San Diego County.
Recording for the July 28, 2021 SDMMP Mgmt. and Mon. Coordination Meeting. Dr. Barbara Kus - &quot;Distribution and Demography of Coastal Cactus Wrens in southern San Diego County&quot;
In collaboration with Groundwork San Diego-Chollas Creek (Groundwork) and the San Diego
Association of Governments (SANDAG), AECOM was selected to enhance and restore existing
and potential coastal cactus wren (Campylorhynchus brunneicapillus) and coastal California
gnatcatcher (Polioptila californica californica) habitat in Encanto and Radio Canyons.
Groundwork is an independent, not-for-profit environmental organization that works within San
Diego’s Chollas Creek Watershed to improve the environment, economy, and quality of life in
the area through local community projects. Over the past several years, Groundwork has been
an integral part of the restoration and enhancement of the Chollas Creek area. The project was
funded by SANDAG under the Transnet Environmental Mitigation Program (EMP).
In collaboration with Groundwork San Diego-Chollas Creek (Groundwork) and the San Diego
Association of Governments (SANDAG), AECOM was selected to enhance and restore existing
and potential coastal cactus wren (Campylorhynchus brunneicapillus) and coastal California
gnatcatcher (Polioptila californica californica) habitat in Encanto and Radio Canyons.
Groundwork is an independent, not-for-profit environmental organization that works within San
Diego’s Chollas Creek Watershed to improve the environment, economy, and quality of life in
the area through local community projects. Over the past several years, Groundwork has been
an integral part of the restoration and enhancement of the Chollas Creek area. The project was
funded by SANDAG under the Transnet Environmental Mitigation Program (EMP).
BACKGROUND
In collaboration with Groundwork San Diego and the San Diego Association of Governments (SANDAG),
AECOM was selected to enhance and restore existing and potential coastal cactus wren
(Campylorhynchus brunneicapillus) and California gnatcatcher (Polioptila californica californica) habitat
in Encanto and Radio Canyons. Groundwork San Diego-Chollas Creek (Groundwork) is an independent,
not-for-profit, environmental business that works within San Diego's Chollas Creek Watershed to
improve the environment, economy, and quality of life in the area through local community projects.
Over the past several years, Groundwork has been an integral part of the restoration and enhancement
of the Chollas Creek area. The project was funded by SANDAG under the Transnet Environmental
Mitigation Program (EMP).
This project was identified as an opportunity to create and enhance habitat for the coastal cactus wren
(Photo 1) and California gnatcatcher and offer a more native landscape for the community surrounding
the sites. The habitat enhancement and restoration objectives included removal of nonnative plant
cover and planting of approximately 20,000 new cholla cactus (Cylindropuntia prolifera), which is
preferred nesting habitat for the coastal cactus wren. The California gnatcatcher would also benefit from
the improved habitat, since this species is also present in the project area and uses maritime succulent
scrub habitat in conjunction with coastal sage scrub habitat. Enhancement and expansion of areas with
existing occupied gnatcatcher and cactus wren habitats improves and expands habitat for both species,
improving the chances for the long-term health of local and regional populations. This project also
offered a unique opportunity for students and residents within the surrounding canyon communities to
play an important role in project planning and implementing of the coastal cactus wren.
AECOM and Groundwork collaborated in the execution of project tasks. AECOM led the site mapping,
habitat restoration, monitoring, maintenance, and reporting tasks, and Groundwork led the educational,
community involvement, and publicity aspects of the project.
The project is located in the community of Encanto in southern San Diego, California, north of Market
Street between Euclid Avenue and Merlin Drive (Figures 1 and 2). The total area of both canyons
combined is 73.62 acres. Encanto Canyon consists of 37.24 acres and Radio Canyon consists of 36
The primary goal of this three-year project was to support the restoration and recovery of coastal cactus wren (CACW) populations in the San Pasqual Valley/Lake Hodges region including locations identified under coordination with the South San Diego County Coastal Cactus Wren Conservation Implementation Plan. In pursuit of this goal, the San Diego Zoo Institute for Conservation Research aspired to accomplish two tasks: 1) establish and maintain a cactus nursery to supply cacti for habitat restoration to land managers in North County and 2) control invasive species and restore habitat in potential cactus wren nesting habitat.
This document 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.
We surveyed for coastal Cactus Wren (Campylorhynchus brunneicapillus) in 378 established plots in southern San Diego County in 2021, encompassing 3 genetic clusters (Otay, Lake Jennings, and Sweetwater/Encanto). Two surveys were completed at each plot between March 1 and July 31. Cactus Wrens were detected in 130 plots (34 percent of plots), remaining virtually the same as the percentage of plots occupied in 2020 (35 percent). There were 113 Cactus Wren territories detected across all survey plots in 2021, an increase from 109 in 2020. At least 86 percent of Cactus Wren territories were occupied by pairs, and 50 fledglings were observed in 2021.
We observed 48 color-banded Cactus Wrens in 2021, 44 of which we could identify to individual. Adults of known age ranged from 2 to at least 7 years old. Adult Cactus Wrens moved, on average, 0.1 kilometers (maximum 0.5 kilometers) from their 2020 territories to their 2021 territories. No known-identity Cactus Wrens moved between genetic clusters from 2020 to 2021.
Vegetation at Cactus Wren plots typically was dominated by coastal sage scrub shrubs, such as California sagebrush (Artemisia californica), California buckwheat (Eriogonum fasciculatum), lemonadeberry (Rhus integrifolia), and San Diego sunflower (Bahiopsis laciniata). Twenty-nine percent of plots contained blue elderberry (Sambucus nigra ssp. caerulea), and Cactus Wrens occupied proportionally more plots with elderberry than plots without elderberry. Very little dead or unhealthy cactus was observed within all survey plots, and the plots that were occupied by Cactus Wrens were likely to contain more healthy cactus than plots that were not occupied by Cactus Wrens. Thirteen percent of plots had 5 percent or less of the cactus crowded or overtopped by vines and shrubs. Although in 2020, Cactus Wrens occupied proportionally more plots with 5 percent or less of cactus crowded or overtopped by vines and shrubs, this pattern was not found in 2021. Non-native annual cover was 5 percent or less at 29 percent of plots and, unlike in 2020, Cactus Wrens appeared to occupy proportionally more plots with less non-native annual cover than plots with more than 5-percent annual cover.
The primary goal of this three-year project was to support the restoration and recovery of coastal cactus wren (CACW) populations in the San Pasqual Valley/Lake Hodges region including locations identified under coordination with the South San Diego County Coastal Cactus Wren Conservation Implementation Plan. In pursuit of this goal, the San Diego Zoo Institute for Conservation Research aspired to accomplish two tasks: 1) establish and maintain a cactus nursery to supply cacti for habitat restoration to land managers in North County and 2) control invasive species and restore habitat in potential cactus wren nesting habitat.
Surveys for coastal Cactus Wren (Campylorhynchus brunneicapillus) were done in 378 established plots in southern San Diego County in 2020, encompassing three genetic clusters (Otay, Lake Jennings, and Sweetwater/Encanto genetic clusters). Two surveys were completed at each plot between March 1 and July 31. Cactus Wrens were detected in 131 plots (35 percent of plots). This is a slight increase over the proportion of occupied plots in 2019. One hundred and nine Cactus Wren territories were detected across all survey plots in 2020, an increase from 83 in 2019. At least 85 percent of Cactus Wren territories were occupied by pairs, and 62 fledglings were observed in 2020.
There were 89 color-banded Cactus Wrens observed in 2020, 84 of which we could identify to individual. Adults of known age ranged from 1 to at least 6 years old. Adult Cactus Wrens moved on average 0.2 kilometers (km; maximum 3.8 km) from their 2019 territories to their 2020 territories. Cactus Wrens that fledged in 2019 moved on average 1.2 km (maximum 9.9 km) to their 2020 territories. No known-identity Cactus Wrens moved between genetic clusters from 2019 to 2020.
Vegetation at Cactus Wren plots typically was dominated by coastal sage scrub shrubs such as California sagebrush (Artemisia californica), lemonadeberry (Rhus integrifolia), California buckwheat (Eriogonum fasciculatum), and broom baccharis (Baccharis sarothroides). Very little dead or unhealthy cactus was observed within Cactus Wren survey plots. Thirty-eight percent of plots had at least 25 percent of the cactus crowded or overtopped by vines and shrubs. Non-native annual cover was greater than 25 percent at 35 percent of plots.
Surveys and monitoring for the coastal Cactus Wren
(Campylorhynchus brunneicapillus) were completed in
San Diego County between March 2015 and July 2019.
A total of 383 plots were surveyed across 3 genetic clusters
(Otay, Lake Jennings, and Sweetwater/Encanto). From 2015
to 2019, 317 plots were surveyed 8 times (twice per year in
2015, 2017–19). Additional plots were added in later years as
wrens were discovered in new locations. We found differences
in the proportion of plots occupied in the genetic clusters,
with a lower proportion of plots occupied in the Otay cluster
than in the Lake Jennings and Sweetwater/Encanto clusters
in all years. Plot occupancy increased each year in the Otay
and Sweetwater/Encanto clusters but not in the Lake Jennings
cluster. The number of Cactus Wren territories increased from
2015 through 2018, and then decreased in 2019 in all three
genetic clusters.
The Safari Park Biodiversity Reserve is one of the last remaining strongholds for coastal cactus wrens in
San Diego County, and the cactus scrub supports the greatest abundance of cactus wrens in San Pasqual
Valley. The 2007 Witch Creek fire damaged much of the cactus scrub at the Safari Park and throughout
the San Pasqual Valley. In 2010, we were awarded a TransNet grant to support and enhance the survival
of coastal cactus wrens in the Valley using a strategic, multi-faceted approach. Specifically we proposed
to: (1) construct a cactus propagation and salvage center that will serve as a long-term resource
providing native cacti materials for restoration projects throughout the North County; (2)
collect/propagate over 1,200 prickly-pear cacti per year for restoration in the San Pasqual Valley
(including the Safari Park Biodiversity Reserve and partner-managed MSCP lands); (3) enhance 45 acres
within the Safari Park Biodiversity Reserve through cacti enrichment plantings; (4) monitor
establishment and growth of planted cacti; and monitor cactus wren abundance, distribution, and
habitat use in relation to habitat characteristics and enhancement efforts.
The coastal cactus wren (Camphylorynchus brunneicapillus sandiegensis) is one of numerous species in decline in San Diego County. Limited to prickly pear (Opuntia.sp.) and cholla (Cylindropuntia sp.) cacti for nesting, the resident songbird's persistence in the county relies upon the existence of such habitat. Urbanization, agriculture, and fire have reduced cactus in San Diego County, leaving only a remnant of the once abundant habitat for the coastal cactus wren (Shuford & Gardali 2008). Large aggregations of cactus wrens exist in areas where urbanization and agriculture have been excluded, such as on the Fallbrook Naval Weapons Station (NWS), on several sites in San Pasqual Valley, and around both Lake Jennings and the Sweetwater Reservoir. Smaller groups dwell in urban canyons, nature reserves, and otherwise undeveloped areas around the county as well. On the order of 200 known coastal cactus wren territories currently exist on public and otherwise preserved properties in San Diego County, likely representing a major reduction from historical population sizes (Shufard & Gardali 2008).
We surveyed for coastal Cactus Wren
(Campylorhynchus brunneicapillus) in 507 established
plots in San Diego County in 2022, encompassing 4 genetic
clusters (Otay, Lake Jennings, Sweetwater/Encanto, and
San Pasqual). Two surveys were completed at each plot
between March 1 and July 31. Cactus Wrens were detected in
214 plots (42 percent of plots). Cactus Wrens were detected in
31 percent of plots that have been consistently surveyed since
2020, indicating less plot occupancy than in 2021 (34 percent)
and 2020 (35 percent). There were 202 Cactus Wren territories
detected across all survey plots in 2022. In plots that have
been consistently surveyed since 2020, we documented
94 territories, which is a decrease from 113 territories in 2021
and 109 in 2020. The number of territories declined from 2021
to 2022 in the Lake Jennings and Otay genetic clusters but
remained virtually the same in the Sweetwater/Encanto genetic
cluster. At least 78 percent of Cactus Wren territories were
occupied by pairs, and 134 fledglings were observed in 2022.
We observed 24 banded Cactus Wrens in 2022, 20 of
which we could identify individually by band combination.
Adults of known age ranged from 3 to at least 7 years old.
All individually identifiable adult Cactus Wrens remained on
the same territory in 2022 that they occupied in 2021, and
we detected no movement of banded Cactus Wrens between
genetic clusters.
Vegetation at Cactus Wren survey plots was
dominated by coastal sage scrub shrubs, such as California
sagebrush (Artemisia californica), California buckwheat
(Eriogonum fasciculatum), lemonadeberry (Rhus integrifolia),
jojoba (Simmondsia chinensis), and San Diego sunflower
(Bahiopsis laciniata). No definitive signs of fungal pathogens
were observed on cactus within and around survey plots. Blue
elderberry (Sambucus nigra ssp. caerulea) was detected at
39 percent of plots, and Cactus Wrens occupied proportionally
more plots with elderberry than plots without elderberry. Very
little dead or unhealthy cactus was observed within all survey
plots, and the plots that were occupied by Cactus Wrens were
likely to contain fewer dead cactus than plots that were not occupied by Cactus Wrens. Almost 80 percent of plots had
more than 5 percent of cactus crowded or overtopped by
vines and shrubs. Similar to 2020, Cactus Wrens occupied
proportionally more plots with 5 percent or less of cactus
crowded or overt
Navajo Canyon Open
Space and Chollas Radio Canyon Open Space both have recent recorded occurrences of Coastal Cactus
Wren.
The primary goal is to create, enhance and expand existing Coastal Cactus Wren (CACW) habitat and
reduce the threat of wildfire and invasive plant conversion by replacing areas of invasive flashy fuels with
native cactus in City of SD Chollas Radio Canyon and Navajo Canyon Open Spaces. The main objectives to
reach these goals are 1) to perform brush removal and invasive weed control within newly proposed and
existing CACW sites, and 2) harvest and plant cactus cuttings from existing mature native prickly pear and
coast cholla to create more CACW habitat. Urban Corps crews will be hired to perform initial and ongoing
brush and weed clearing so that City staff can perform herbicide applications to control the weeds in the
CACW habitat. Urban Corps labor will also be used to harvest cactus cuttings from existing specimens
onsite at both locations and install them in the CACW habitat enhancement sites. Urban Corps crews will
also be used to install erosion control materials. City staff will oversee and manage the project. This
project will build on past projects performed by AECOM and Urban Corps that worked to create and
enhance Coastal Cactus Wren habitat in Chollas Radio Canyon Open Space.
Merkel & Associates, Inc conducted the fifth annual monitoring assessment for the Salt
Creek Coastal Cactus Wren Habitat Restoration Project. Quantitative monitoring was performed on
May 8, 2014 (bird survey) and September 2, 2014 (vegetation survey). Information from qualitative
assessments of the site was obtained in April, July, and October of 2014 and is provided with this
report (Appendix 3).
Avian point counts and vegetation coverage/cactus height was acquired and analyzed for 6 preestablished
monitoring stations. These monitoring stations include two restored areas (Stations 1 and
2), two areas that have had previous records of coastal cactus wren (Campylorhynchus
brunneicapillus) occupation (Stations 3 and 4), and two areas that were assumed to be suitable for
cactus wren occupation but no wrens had been observed prior to this study (Stations 5 and 6). The
purpose of this report is to provide information in regards to changes in habitat and avian use over
time (approximately 5 years) at each of the monitoring stations. This report serves as the final annual
report of a 5-year monitoring program.
Southern California supports both coastal and desert populations of the Cactus Wren
(Campylorhynchus brunneicapillus). In coastal regions, Cactus Wrens are year round residents of
coastal sage scrub plant communities that contain cholla and/or pricklyâ€pear cactus tall enough
(>1 m) to support and protect nests. Mature stands of cactus are patchily distributed within
coastal sage scrub leading to a naturally patchy distribution of Cactus Wren in coastal southern
California. Despite this uneven distribution, Cactus Wrens were historically widespread and
abundant. In the last few decades, coastal populations have shown dramatic declines and are of
great conservation concern (Sauer et al. 1999; Proudfoot et al. 2000; Solek and Szijj 2004;
Mitrovich and Hamilton 2007). This report presents the preliminary results of studies
conducted in 2012 investigating Cactus Wren genetics and parasite load, foraging ecology, and
banded bird resighting surveys, to followâ€up on the 2009 to 2011 Cactus Wren reproduction,
dispersal and survival study, in Orange County’s Central and Coastal Natural Community
Conservation Plan/Habitat Conservation Plan (NCCP/HCP).
Southern California supports both coastal and desert populations of the Cactus Wren
(Campylorhynchus brunneicapillus). In coastal regions, Cactus Wrens are year round residents of
coastal sage scrub plant communities that contain cholla and/or pricklyâ€pear cactus tall enough
(>1 m) to support and protect nests. Mature stands of cactus are patchily distributed within
coastal sage scrub leading to a naturally patchy distribution of Cactus Wren in coastal southern
California. Despite this uneven distribution, Cactus Wrens were historically widespread and
abundant. In the last few decades, coastal populations have shown dramatic declines and are of
great conservation concern.
Develop and begin initial implementation of a subwatershed-level
management plan to restore and manage native habitat to support a stable, resilient Coastal
Cactus Wren population in the San Pasqual Valley/Lake Hodges region of the San Dieguito
Watershed. To accomplish this goal, activities have been divided into a series of Tasks and
Phases to be implemented over a two-year period.
The short-term Otay River Valley Cactus Wren Fence Project reduced threats to coastal cactus
wren (Campylorhynchus brunneicapillus sandiegensis; CACW) habitat by providing access control
via fence and sign installation for the 3-year Otay River Valley Cactus Wren project (SANDAG
Grant Number 5004730). The overarching goal of the Cactus Wren project is to increase the
amount of suitable habitat and improve connectivity for the coastal cactus wren along the Otay
River Valley through restoration and enhancement of degraded habitat areas. CACW is a
Management Strategic Plan (MSP) Category SO species (significant occurrence(s) at risk of loss
from MSP area). This short-term project fulfills the immediate need for access control in the
CACW restoration area by deterring off-road vehicles, bikers, equestrians, and other trails users
from entering the 3-year project site.
Merkel & Associates, Inc. has conducted the second annual monitoring assessment for the Salt Creek Coastal Cactus Wren Habitat Restoration Project. Quantitative monitoring was performed on May 10, 2011 (bird survey) and August 17, 2011 (vegetation survey). Information from qualitative assessments of the site was obtained in April, July, and October of 2011 and is provided with this report.
A study to determine the status of the coastal cactus wren was conducted in the Coastal Reserve in 2006. The purpose of this study was to determine the status of the wren in the Central Reserve using the same methodology so that a baseline condition for cactus wren could be established reserve-wide.
All of the cactus resources in the Central Reserve were mapped in the spring of 2008, and two rounds of focused surveys for the cactus wren were conducted in cactus scrub judged mature enough to support nesting pairs. Unanticipated fires burned approximately 75%
of the Central Reserve in 2007, so methods were developed to collect data that would enable an evaluation of the impact of the fires on the cactus resources within those areas. A total of 1,855 acres of cactus scrub was mapped in the Central Reserve. Of that total, 1,420 acres sustained Low, Moderate, or High levels of damage during the fires, 75% of which (1,059 acres) was severely burned and is not suitable for supporting nesting cactus wrens. Six hundred eighty three (683) acres were judged suitable for occupancy by cactus wrens and surveyed.
Within the 683 acres of cactus scrub judged suitable for occupancy by cactus wrens, 263 sites were delineated and surveyed for adult cactus wrens. Fifty eight (58) sites were found to be occupied during the first round of surveys, and 56 sites were found to be occupied during the second round of surveys. These occupied sites represent an estimated 67 territories, a decline of 82.1% since 374 territories were estimated in 2004.
A study to determine the status of the coastal cactus wren was conducted in the Coastal
Reserve in 2006. The purpose of this study was to determine the status of the wren in the
Central Reserve using the same methodology so that a baseline condition for cactus wren
could be established reserve-wide.
All of the cactus resources in the Central Reserve were mapped in the spring of 2008, and
two rounds of focused surveys for the cactus wren were conducted in cactus scrub judged
mature enough to support nesting pairs. Unanticipated fires burned approximately 75%
of the Central Reserve in 2007, so methods were developed to collect data that would
enable an evaluation of the impact of the fires on the cactus resources within those areas.
A total of 1,855 acres of cactus scrub was mapped in the Central Reserve. Of that total,
1,420 acres sustained Low, Moderate, or High levels of damage during the fires, 75% of
which (1,059 acres) was severely burned and is not suitable for supporting nesting cactus
wrens. Six hundred eighty three (683) acres were judged suitable for occupancy by
cactus wrens and surveyed.
Within the 683 acres of cactus scrub judged suitable for occupancy by cactus wrens, 263
sites were delineated and surveyed for adult cactus wrens. Fifty eight (58) sites were
found to be occupied during the first round of surveys, and 56 sites were found to be
occupied during the second round of surveys. These occupied sites represent an
estimated 67 territories, a decline of 82.1% since 374 territories were estimated in 2004.
The primary goal of the Rice Canyon Sensitive Plant Species Management Project (project) was to reduce the threat
from invasive stinknet (Oncosiphon pilulifer) and illegal trespassing to sensitive plant species. Reducing these threats
was a benefit to sensitive animal species that occupy Rice Canyon as well. Sensitive plant species that were the focus
of the project include Otay tarplant (Deinandra conjugens), San Diego thornmint (Acanthomintha ilicifolia), and
Orcutt’s bird’s-beak (Dicranostegia orcuttiiana). Sensitive animal species that also occur in Rice Canyon include coastal
California gnatcatcher (Polioptila californica californica) and coastal cactus wren (Campylorhynchus brunneicapillus
sandiegensis) among other Multiple Species Conservation Plan-covered species.
Merkel & Associates, Inc. conducted the third annual monitoring assessment for the Salt Creek Coastal Cactus Wren Habitat Restoration Project. Quantitative monitoring was performed on May 10, 2012 (bird survey) and October 5, 2012 (vegetation survey). Information from qualitative assessments of the site was obtained in April, July, and October of 2012 and is provided with this report.
Through the support of the San Diego Association of Governments (SANDAG), the City of Chula
Vista was able to complete an 18-month land management program focused on increasing the
quality of habitat and improving connectivity for the coastal cactus wren (Management and
Monitoring Strategic Plan [MSP] category SO; significant occurrence at risk of loss from MSP)
along Salt Creek through shrub thinning of approximately 6 acres within suitable wren habitat.
This program addressed the immediate needs of cactus wren within Salt Creek where loss and
degradation of existing wren habitat has occurred due to vegetation succession processes, an
increase of invasive plants, unauthorized off-road vehicle use, and drought.
Merkel & Associates, Inc. conducted the first annual monitoring assessment for the Salt Creek Coastal Cactus Wren Habitat Restoration Project. Quantitative monitoring was performed on May 3, May 4, September 9, and September 10, 2010. Information from qualitative assessments of the site was obtained in June, August, and October of 2010 and is also provided in this report.
The After the Fires Funds 2007 were utilized to provide immediate benefits to wildlife by expanding habitat adjacent to areas that did not burn and contained one or both of the restoration project's species of focus; California Gnatcatcher (Polioptila californica)and Coastal Cactus Wren
(Campylorhynchus brunneicapillus sandiegensis). Work on this project was guided by the goal of providing immediate benefits to these birds because the fate of the San Dieguito River Park's ("Park") populations will have regionwide implications.
A study to determine the status of the coastal cactus wren was conducted in the Coastal
Reserve in 2006. The purpose of this study was to determine the status of the wren in the
Central Reserve using the same methodology so that a baseline condition for cactus wren
could be established reserve-wide.
All of the cactus resources in the Central Reserve were mapped in the spring of 2008, and
two rounds of focused surveys for the cactus wren were conducted in cactus scrub judged
mature enough to support nesting pairs. Unanticipated fires burned approximately 75%
of the Central Reserve in 2007, so methods were developed to collect data that would
enable an evaluation of the impact of the fires on the cactus resources within those areas.
A total of 1,855 acres of cactus scrub was mapped in the Central Reserve. Of that total,
1,420 acres sustained Low, Moderate, or High levels of damage during the fires, 75% of
which (1,059 acres) was severely burned and is not suitable for supporting nesting cactus
wrens. Six hundred eighty three (683) acres were judged suitable for occupancy by
cactus wrens and surveyed.
Within the 683 acres of cactus scrub judged suitable for occupancy by cactus wrens, 263
sites were delineated and surveyed for adult cactus wrens. Fifty eight (58) sites were
found to be occupied during the first round of surveys, and 56 sites were found to be
occupied during the second round of surveys. These occupied sites represent an
estimated 67 territories, a decline of 82.1% since 374 territories were estimated in 2004.
The University of California at Irvine (UCI) manages the UCI Ecological Preserve, a 60
acre area of natural habitat located on the main UCI campus. The Preserve has been
subject to ongoing avian surveys and ecological restoration efforts for over a decade. In
2002, UCI contracted Harmsworth Associates to conduct surveys for the California
gnatcatcher (Polioptila californica californica) and cactus wren (Campylorhynchus
brunneicapillus) to determine the number and location of breeding pairs of each species
at the Preserve.
This report summarizes the results of surveys for gnatcatcher and cactus wren for the
2005 season.
This report provides a progress summary of the ongoing habitat restoration project for the San Diego cactus wren (Campylorhynchus brunneicapillus sandiegensis) within the central property of the Lakeside Linkage Preserve (Preserve) located in the City of Lakeside, San Diego County, California (Figures 1 and 2) and provides details on the fifth year of the five-year post-installation monitoring period (August 1, 2015 through July 31, 2016).
The Bernardo Bay cactus restoration project around Hodges Reservoir included the planting of
native cactus on 20 acre clusters surrounding the hills of the reservoir to enhance and re-create
the cactus habitat that once existed under pre-Witch Fire conditions. This project would allow
the endangered Cactus wren to work its way back from eastern populations along the San
Dieguito River (SDgR) to the west. Additionally, the cactus will help stabilize the slopes around
Hodges Reservoir and close off unauthorized trails that will also reduce erosion and maintain
higher water quality in the reservoir
The Otay Ranch Preserve (Preserve) consists of approximately 525 acres in the San Ysidro
Mountains and approximately 826 acres in Salt Creek in the City of Chula Vista (City) in San
Diego County. Dudek biologists have performed the following surveys: vegetation mapping in
May and June 2008, focused botanical surveys in spring 2009, general butterfly surveys in 2008,
focused surveys for quino checkerspot butterfly (Euphydryas editha quino) in spring 2009,
focused surveys for coastal California gnatcatcher (Polioptila californica californica) in
spring 2008, avian point count surveys in summer/fall 2008, and large and medium mammal
surveys in spring 2009. Herpetology trap surveys are currently in process. This report documents
the results of Dudek's field work.
Effective management of coastal populations of the Cactus Wren (Campylorhynchus
brunneicapillus) is considered one of the great challenges in bird conservation for
southern California. Loss and fragmentation of habitat due to development, agricultural
displacement, and high frequency wildfire, have led to major declines in this species
throughout large portions of the region. Even on protected conservation lands
populations are vulnerable to local extinction, and the need for active management of this
species is becoming increasingly obvious.
In a single field season, we captured, color-banded, and relocated 10 cactus wrens in
order to study the biological and behavioral response of adult and juvenile wrens to
translocation (Figure 1). In this study, we report on the first completed phase of postrelease
monitoring and use the collected information to evaluate whether translocation
might be an effective tool for management of isolated populations of cactus wrens in
coastal southern California.
In this study, we mined museum collections for genetic material collected prior to
widespread urban development over the second half of the 20th century in coastal southern
California. We analyzed population structure and genetic diversity in these historical
populations of cactus wrens using a suite of microsatellites previously developed for the species
(Barr et al. 2012). Old and degraded sources of DNA can be difficult to amplify and present high
levels of allelic dropout and null alleles, both of which can confound genetic structure analyses.
4
With a large number of available loci, we were able to rigorously limit analyses to only those
with reliable and consistent amplification. We also utilized analyses that explicitly account for
the presence of allelic dropout. With these data, we assessed historical population structure
and genetic diversity in cactus wrens in coastal southern California and compared these to
contemporary patterns.
The San Dieguito River Valley (SDRV), consisting of the San Pasqual Valley and Lake Hodges, is one of the most significant natural open spaces in San Diego County. This area supports a major recreational amenity, the San Dieguito River Park (SDRP), as well as habi-tat for several species covered and permitted by the Multiple Species Conservation Pro-gram (MSCP). The 2007 Witch Fire burned a substantial portion of the SDRV, including more than 60% of the SDRP. The extremely high natural resource and recreational values in this area emphasize the need and urgency for fire recovery efforts.
Consistent with our proposal dated March 25, 2008, the Irvine Ranch Conservancy and consulting biologist Robert Hamilton have built, installed, and monitored several experimental artificial nesting substrates for the Cactus Wren (Campylorhynchus brunneicapillus; CACW) in the Irvine Ranch Wildlands in central and coastal Orange County, California, within the larger Nature Reserve of Orange County. The wren is one of two avian ―focal species‖ of the Natural Communities Conservation Plan (NCCP) for coastal sage scrub in southern California, and its populations in both the central and coastal NCCP reserves are of special conservation concern due to rapidly declining numbers, reduced availability of favorable habitat with adequate nesting sites related to the wildfires of the past 16 years, and increasingly isolated sub-populations.
The 2014 avian survey of the Bernardo Mountain Preserve, San Dieguito River Park, San Diego
County, California determined the point locations, territories, and breeding status of two rare
songbirds, the California Gnatcatcher (Polioptila californica californica) and the Coastal Cactus
Wren (Campylorhynchus brunneicapillus cousei). Eleven field surveys conducted between 14
March and 21 June detected a total of twelve gnatcatcher and three Cactus Wren territories
within the preserve. This compares favorably with previous surveys conducted after the Witch
Fire of 2007 despite the continuation of a three-year drought. Our observations show that the
gnatcatcher, in particular, has expanded into revegetated areas. Cactus Wrens, with their more
specific requirements, are still largely confined to cactus scrub that did not burn in 2007 as
replanted cactus has yet to reach a height suitable for nest-building. Other vertebrates noted
during the survey include sixty-six additional species of birds, four species of mammals, and five
species of reptiles.
To identify, based on best available science, conservation actions to ensure the
persistence of the coastal cactus wren throughout its range (Ventura, Los Angeles, San
Bernardino, Orange, Riverside, and San Diego Counties).
To document the historic and current distribution of coastal cactus wren in southern
California, and update this information as new information becomes available.
-Use data to inform acquisitions in Riverside MSHCP
-Identify occupied habitat for focused conservation/management
-Identify areas of suitable habitat for which data is lacking, and conduct
surveys of those locations to document presence/absence of coastal cactus wren
To identify and implement research actions that will best inform conservation of the
species.
To develop and implement a standardized long-term monitoring program for the coastal
cactus wren range-wide; develop and maintain a regional CACW monitoring database
that is readily accessible via the web.
Ensure that conservation actions are integrated with established conservation plans that
list the cactus wren as a target species.