HomeMy WebLinkAbout8-7-2020 Canyon Loop Trail Improvement Project_CAGN Surveys 2020_TE-88331A-2
August 7, 2020 178669
City of Diamond Bar
Contact: Mr. Ryan Wright
21810 Copley Drive
Diamond Bar, CA 91765
SUBJECT: Results of Coastal California Gnatcatcher and Cactus Wren Focused Surveys for the
Canyon Loop Trail Improvement Project in the City of Diamond Bar, Los Angeles
County, California
Dear Mr. Wright:
Michael Baker International (Michael Baker) is pleased to submit this report to the City of Diamond Bar
(City) documenting the results of coastal California gnatcatcher (Polioptila californica californica; CAGN)
and cactus wren (Campylorhynchus brunneicapillus; CACW) focused surveys conducted for the Canyon
Loop Trail Improvement Project (project or project site) located in the City of Diamond Bar, Los Angeles
County, California. Surveys occurred during the 2020 field season, when Michael Baker was contracted by
the City to perform CAGN and CACW surveys in suitable habitat within 500 feet of the proposed project.
Project Location
The survey area include the project site plus suitable CAGN and CACW habitat within a 500-foot buffer,
and is generally located south of State Route 60, east of State Route 57, north of Grand Avenue, and west
of Chino Hills Parkway in the City of Diamond Bar, Los Angeles County, California (refer to Figure 1,
Regional Vicinity, in Attachment A). The survey area is depicted in Sections 11 and 14 of Township 2
south, Range 9 west, on the United States Geological Survey’s (USGS) San Dimas, California 7.5-minute
quadrangle (USGS 1981). Specifically, the survey area is located along the Canyon Loop Trail within
Summitridge Park (refer to Figure 2, Survey Area, in Attachment A).
Project Description
The City of Diamond Bar proposes to implement a series of improvements to the existing Canyon Loop
Trail. The intent of the project is primarily to realign the trail, improve drainage to minimize erosion of the
trail, enhance the use of the trail where the gradients are steep, re-grade cross slopes, and consider amenities
such as directional and interpretive signage, rest areas with benches, small shade shelters, climbing steps
with cobblestone swale channelization, and water diverting improvements where necessary. Such trail
improvements will reward hikers and visitors with 360-degree views of open space.
Regulatory Framework
Federal Endangered Species Act of 1973
As defined within the Federal Endangered Species Act of 1973 (FESA), an endangered species is any
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animal or plant listed by regulation as being in danger of extinction throughout all or a significant portion
of its geographical range. A threatened species is any animal or plant that is likely to become endangered
within the foreseeable future throughout all or a significant portion of its geographical range. Without a
special permit, Federal law prohibits the “take” of any individuals or habitat of Federally-listed species.
Under Section 9 of the FESA, take is defined as “harass, harm, pursue, hunt, shoot, wound, kill, trap,
capture, or collect or attempt to engage in any such conduct.” The term “harm” has been clarified to include
“any act which actually kills or injures fish or wildlife, and emphasizes that such acts may include
significant habitat modification or degradation that significantly impairs essential behavioral patterns of
fish or wildlife.” Enforcement of FESA is administered by the U.S. Fish and Wildlife Service (USFWS).
Under the definition used by the FESA, “Critical Habitat” refers to specific areas within the geographical
range of a species that were occupied at the time it was listed that contain the physical or biological features
that are essential to the survival and eventual recovery of that species and that may require special
management considerations or protection, regardless of whether the species is still extant in the area. Areas
that were not known to be occupied at the time a species was listed can also be designated as Critical Habitat
if they contain one or more of the physical or biological features that are essential to that species’
conservation and if the occupied areas are inadequate to ensure the species’ recovery. If a project may result
in take or adverse modification to a species’ designated Critical Habitat and the project has a Federal nexus,
the project proponent may be required to provide suitable mitigation. Projects with a Federal nexus may
include projects that occur on Federal lands, require Federal permits (e.g., Clean Water Act Section 404
permit), or receive any Federal oversight or funding. If there is a Federal nexus, then the Federal agency
that is responsible for providing funds or permits would be required to consult with the USFWS under the
FESA.
Species Background
Coastal California Gnatcatcher
CAGN is a Federally threatened species with restricted habitat requirements, being an obligate resident of
sage scrub habitats, particularly—but not exclusively—those that are dominated by California sagebrush
(Artemisia californica). This species generally occurs below 750 feet elevation in coastal regions and below
1,500 feet inland. It ranges from Ventura County south to San Diego County and northern Baja Califo rnia
and is less common in sage scrub with a high percentage of tall shrubs. CAGN is considered a short-distance
disperser through contiguous, undisturbed habitat (USFWS 2010). However, juveniles are capable of
dispersing long distances (up to 14 miles) across fragmented and highly disturbed sage scrub habitat
(USFWS 2010). CAGN prefers habitat with more low-growing vegetation (< 3 feet high). CAGN breeds
between mid-February and the end of August, with peak activity from mid-March to mid-May. Population
declines are attributed to loss of sage scrub habitat due to development, as well as brown-headed cowbird
(Molothrus ater) nest parasitism. Federally designated Critical Habitat for CAGN is not located within or
directly adjacent to the survey area. The primary constituent elements essential to support the biological
needs of foraging, reproducing, rearing of young, intra-specific communication, dispersal, genetic
exchange, or sheltering for CAGN are:
1) Dynamic and successional sage scrub habitats and associated vegetation (Riversidean alluvial fan
sage scrub, coastal sage-chaparral scrub, etc.) that provide space for individual and population
growth, normal behavior, breeding, reproduction, nesting, dispersal and foraging; and
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2) Non-sage scrub habitats such as chaparral, grassland, and riparian areas in proximity to sage scrub
habitats that provide linkages to help with dispersal, foraging, and nesting (USFWS 2007).
The survey area provides abundant suitable habitat for CAGN, although there are large sections of the
survey area that are highly disturbed by non-native plants.
Cactus Wren
CACWs are a somewhat common avian species found within arid and semi-arid regions of southern
California. The subspecies coastal cactus wren (C. b. sandiegensis; CCAWC) is found within a very limited
range of southern California and is designated by CDFW as a Species of Special Concern (SSC). CCACW
has more heavily spotted underparts more closely blending into the dark breast spot, less of a cinnamon-
buff wash to the underparts, and extensive white in the interior tail feathers, as opposed to the continental
desert subspecies and subspecies along the Los Angeles County coast, C.b. anthonyi, which has finer belly
spotting more demarcated from the prominent breast spot, a heavier cinnamon-wash buff to the underparts,
and white generally restricted to the outermost tail feather (rectrix 6) and occasionally onto rectrix 5 (the
next feather in from the outside) (Rea and Weaver 1990). CCACW have a range which extends from
extreme northwestern Baja California north at least through the coastal lowlands of San Diego County
(Shuford and Gardali 2008). The actual northern limit of its range is uncertain because of the lack of
specimens from northwestern San Diego County and most of Orange County. However, observations made
in the field based on differences in song (slower frequency and lower pitch) and visual assessments suggest
approximately the vicinity of State Route 74 (Ortega Highway) in Orange County may be the northern limit
of CCACW, and this is apparently the range limit accepted by CDFW (Shuford and Gardali 2008).
CACWS breed from early March through July and are mainly restricted to thickets of chollas
(Cylindropuntia prolifera) or prickly-pear cacti (i.e., Opuntia littoralis, O. oricola) large enough to protect
from predation. Suitable habitat conditions are normally found on south-facing slopes, at bases of hillsides,
or in dry washes. Territories have been recorded as occurring at elevations below 1,500 feet above mean
sea level (amsl) and averaging three (3) acres in size (Shuford and Gardali 2008). CACWs forage on the
ground primarily for insects such as beetles, ants, wasps, grasshoppers, butterflies, and spiders.
The survey area provides several distinct patches of the undisturbed coast prickly pear scrub habitat that is
essential nesting habitat for this species. However, the survey area is well outside of the apparent geographic
range for the coastal sandiegensis subspecies, which ends around State Route 74 based on CDFW mapping
and distribution descriptions in Rea and Weaver (1990). The local subspecies found throughout Los
Angeles County is C. b. anthonyi, although birds on the coastal slope often show some characteristics of
the sandiegensis subspecies (such as more white in the tail than is otherwise expected for this subspecies).
Environmental Setting
The survey area for this effort encompasses suitable CAGN and CACW habitat within 500 feet of the
existing Canyon Loop Trail. It is located in the southeastern corner of Los Angeles County less than 0.5
mile west of the boundary with San Bernardino County. The survey area represents a small subset of the
entire 500-foot buffer around the Canyon Loop Trail and is approximately 30.24 acres in size. It is generally
associated with preserved open space, although many areas within it, particularly the southeast portion of
it, are disturbed with high proportions of non-native plant species as well. An unnamed ephemeral drainage
runs roughly east to west through the center of the survey area. Areas immediately surrounding the survey
area consist of residential developments to the east and west, and undeveloped land to the north and south.
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Coastal California Gnatcatcher and Cactus Wren Focused Survey Results
Topography and Soils
The topography of the survey area is generally steep slopes with associated public trails along hilltops and
other stabilized surfaces. The survey area is located at an elevation of approximately 970 to 1,310 feet amsl.
According to the Custom Soil Resource Report for Los Angeles County, California, Southeastern Part
(USDA 2020), the survey area is underlain by the following soil units: Urban land-Sorrento-Arbolado
complex, 2 to 9 percent slopes (1136), Gaviota-Chumash-Rock outcrop complex, 20 to 55 percent slopes
(1145), and Counterfeit-Urban land complex, 10 to 35 percent slopes, terraced (1232).
Vegetation Communities
Several terrestrial vegetation communities were identified on-site during the field survey. Vegetation
classification was based on A Manual of California Vegetation (Second Edition) (Sawyer et al. 2009) and
cross-checked with Holland (1986). The vegetation communities and land uses present within the survey
area are depicted on Figure 3, Vegetation Communities, in Attachment A, and described in further detail
below. Figure 3 and the descriptions below only include those communities that are suitable habitat for
CAGN and CACW and do not include all vegetation communities or land uses within 500 feet of the
project. All of the following vegetation communities are associated with what would be considered coastal
sage scrub (CSS) habitat.
California Sagebrush – Black Sage Scrub (Holland Equivalent: Diegan Coastal Sage Scrub; Code: 32500)
Approximately 2.13 acres of California sagebrush – black sage scrub vegetation is located within the survey
area. The majority of this vegetation community is dominated by California sagebrush (Artemisia
californica) and black sage (Salvia mellifera) with other shrubs such as white sage (Salvia apiana),
deerweed (Acmispon glaber), and California buckwheat (Eriogonum fasciculatum) occurring as less
frequent sub-dominants. Due to the high density of shrubs within the vegetation community, little to no
herbaceous cover is present.
Disturbed California Sagebrush – Black Sage Scrub (Holland Equivalent: Disturbed Diegan Coastal Sage
Scrub; Code: 32500)
Approximately 17.76 acres of disturbed California sagebrush – black sage scrub vegetation is located
throughout the survey area. This vegetation community is similar in composition and generally in close
proximity to the California sagebrush – black sage scrub found within the survey area but also contains
black mustard (Brassica nigra) and tocalote (Centaurea melitensis) as co-dominant species, in many areas
completely dominating the ground cover between native shrubs.
California Buckwheat Scrub (Holland Equivalent: Disturbed Diegan Coastal Sage Scrub; Code: 32500)
Approximately 0.45 acre of California buckwheat scrub vegetation is located within the western portion of
the survey area. This vegetation community is entirely dominated by California buckwheat, and appears to
be part of a previous restoration effort.
Coast Prickly Pear Scrub (Holland Equivalent: Diegan Coastal Sage Scrub; Code: 32500)
Approximately 9.90 acres of coast prickly pear scrub vegetation is located within the survey area. Coast
prickly pear (Opuntia littoralis) is dominant within this vegetation community, with sticky monkeyflower
(Diplacus aurantiacus) prominently interspersed throughout the area. California buckwheat and California
sagebrush are also present, but in lower proportions compared to coast prickly pear and sticky
monkeyflower.
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Coastal California Gnatcatcher and Cactus Wren Focused Survey Results
Methods
Literature Review
Prior to conducting the focused surveys, Michael Baker performed a detailed literature review and record
search of the project site, vicinity, and region for CAGN and CACW records. The literature search included
a review of any existing biological and focused CAGN survey reports from the project vicinity, as well as
records reported in the CNDDB (CDFW 2020), the USFWS online Critical Habitat Mapper (USFWS
2020), the Cornell Lab of Ornithology’s eBird database (eBird 2020), and a letter written to the City of
Diamond Bar by Hamilton Biological (Hamilton Biological 2019).
Focused Surveys
Protocol surveys for CAGN and CACW were conducted concurrently along, and in areas of suitable habitat
within 500 feet of, the existing Canyon Loop Trail in 2020. All surveys were conducted by Michael Baker
biologists Ryan Winkleman (USFWS recovery permit TE-88331A-2), Ashley Spencer, and Tom
Millington between May and July 2020 (refer to Table 1, Survey Dates, Surveyors, Time, and Weather
Conditions). The surveys followed the CAGN guidelines described in the USFWS protocol Coastal
California Gnatcatcher (Polioptila californica californica) Presence/Absence Survey Guidelines, February
28, 1997 (USFWS 1997) and the CACW guidelines described in Mr. Winkleman’s CDFW scientific
collecting permit (SC-182750017). A total of six (6) surveys were conducted between May 26 and July 1,
2020.
Table 1: Survey Dates, Surveyors, Time, and Weather Conditions
Date Surveyors Time
(start/finish)
Weather Conditions
Temperature (°F)
(start/finish)
Wind Speed Range
(miles per hour)
5/26/20 Ryan Winkleman 0751 / 1222 64 / 83 0-1
6/3/20 Ryan Winkleman,
Ashley Spencer 0713 / 1146 65 / 87 0-8
6/10/20 Ryan Winkleman,
Ashley Spencer 0720 / 1150 69 / 93 0-3
6/17/20 Ryan Winkleman,
Tom Millington 0729 / 1149 62 / 68 0-1
6/24/20 Ryan Winkleman,
Ashley Spencer 0729 / 1142 62 / 76 0-3
7/1/20 Ryan Winkleman,
Ashley Spencer 0730 / 1130 62 / 67 0-1
During each survey, the biologist(s) walked areas of suitable habitat for CAGN and/or CACW within the
survey area and would stop at strategic locations and use taped playback to attempt to lure the target species
into view. All recordings were obtained from xeno-canto.org (2020) and were played with a Pixel 3XL
smartphone amplified with a MIFA F10 portable Bluetooth speaker. In each instance the biologist(s) would
position themselves in an area of suitable habitat and wait up to one (1) minute to see if the target species
could be incidentally detected. If no birds were detected, Mr. Winkleman would play a short recording or
short portion of a recording, followed by approximately one (1) minute of silence before playing another
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recording or continuing the same recording. Recordings were cycled rather than repeated to more
realistically mimic birds making variable vocalizations. In areas where both species could feasibly be
present, the CAGN and CACW recordings were played alternately. If birds responded aurally or flew into
view, all playback was stopped while the biologist(s) observed the bird(s) from a distance and took notes
on age, sex, and behavior. Territory boundaries were mapped in the Avenza smartphone application while
in the field and updated as necessary to record the approximate boundaries over the six surveys. If nesting
behavior was observed, the biologists watched from a safe distance and, if found, plotted the nest location
as accurately as possible using Global Positioning System (GPS) technology and then watched for updates
on subsequent surveys from a safe distance. Photographs were periodically taken during the surveys (refer
to Figure 2, Survey Area, in Attachment A, as well as to Attachment B).
Results
A total of forty-seven (47) wildlife species were observed within the CAGN survey area during the CAGN
focused surveys including four (4) reptiles, seventy-six (76) birds, and five (5) mammals. A complete list
of wildlife species observed during the focused survey is included in Attachment C.
Coastal California Gnatcatcher
Based on information in the CNDDB (CDFW 2020), eBird (eBird 2020), and from a local expert (Benson
personal communication 2020), CAGN is a rare and local resident in the coastal slope of Los Angeles and
San Bernardino Counties. Populations are somewhat widespread but persistent in the project vicinity in Los
Angeles County, spanning across the Chino Hills, San Jose Hills, and Puente Hills. In San Bernardino
County, which is located immediately to the east of the project site, CAGN persists in only four or five
populations in the entire county, including in Chino Hills State Park. Farther to the south, CAGN is
reasonably common in the foothills of the Santa Ana Mountains in Orange County. The project site is not
located within designated Critical Habitat (USFWS 2007).
A minimum of five (5) CAGN territories were mapped during the focused surveys (refer to Figure 4,
Coastal California Gnatcatcher Results, in Attachment A). Four (4) nests were found in two (2) of these
territories, one (1) of which successfully led to chicks fledging. Of the minimum five territories, four (4)
territories (Territories 1, 3, 4, and 5) had chicks fledge in them. The boundaries of Territories 3 and 5
expanded over time due to post-breeding dispersal, with Territory #5 potentially undergoing two separate
instances of dispersal to two areas where no CAGN had been previously detected. A more detailed summary
of CAGN activity in each territory during each survey is provided in Table 2 below.
Cactus Wren
Similar to CAGN, CACW is a rare and local resident on the coastal slope of Los Angeles and San
Bernardino Counties. In Los Angeles County the species is better off but declining, with populations known
from the Chino Hills, San Jose Hills, Puente Hills, and foothills of the San Gabriel Mountains. In adjacent
San Bernardino County, the only known populations are in the upper Santa Ana River wash near
Redlands/Mentone/Highland and near the confluence of Cajon and Lytle Creeks, both far from the survey
area (Benson personal communication 2020). This species is much more common in Orange County in the
foothills of the Santa Ana Mountains and less so in the San Joaquin Hills. Birds in Los Angeles County are
considered to be of the non-sensitive subspecies C.b. anthonyi, although it should be noted that many of the
birds on the coast, including the ones in the survey area, show characteristics, such as the extent of white
barring in the tail feathers, typically associated with the sensitive CCACW.
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Coastal California Gnatcatcher and Cactus Wren Focused Survey Results
Table 2: CAGN Survey Results
Date Territories
Territory #1 Territory #2 Territory #3 Territory #4 Territory #5
5/26/20 Adult male
present and
foraging
solitarily.
Adult male
present and
foraging,
territorial against
juvenile CACW.
Adult female
briefly observed.
CAGN
incidentally
heard, but not
seen.
Adult male
present and
foraging.
Family unit with two adults
and at least two juveniles
present.
6/3/20 Family unit
with two
adults and two
juveniles
present.
Adult male
present and
foraging,
territorial against
juvenile CACW.
No activity
observed.
Family unit
with at least
one juvenile
present.
Adult male present, no
other birds seen.
6/10/20 Adult male
present with
two female-
type birds,
could not see
well enough to
determine age.
Adult pair
present, Nest #1
found. Male
observed perched
over nest in a
shading action.
Family unit
present with at
least two
juveniles in a
new post-
breeding
dispersal area
where not
previously
found.
Adult pair
present and
foraging, no
other birds
seen.
Adult pair present, Nest #1
found. Both male and
female observed incubating
and shading the eggs.
6/17/20 Adult male
present with a
single female-
type bird, not
aged.
Nest #1 failed.
Adult pair
periodically seen
throughout
territory but no
indications of
nesting.
Family unit in
the post-breeding
dispersal area
again.
Adult male
present and
foraging.
Possible
female seen
but not
confirmed.
Adult pair observed
feeding chicks in Nest #1.
Chicks too small to count
from afar.
6/24/20 Adult male
present with a
single female-
type bird, not
aged.
Adult pair present
and nearly
finished building
Nest #2.
Two female-type
birds present in
the post-breeding
dispersal area,
including the
adult female
carrying off
food.
Adult male
present and
foraging.
Adult pair present feeding
chicks in Nest #1. Four
chicks visible in nest. Two
juvenile birds found to the
north, up the hillside above
the territory in mustard,
assumed to be the juveniles
from 5/26 in a post-
breeding dispersal area,
although not previously
found here despite weekly
playback.
7/1/20 Four birds
flew in
together to
playback and
then went out
of sight. Later
observed the
adult pair
bringing food
to juveniles.
Nest #2 failed.
Adult male
observed building
a new nest, Nest
#3.
One bird heard-
only, one
female-type bird
briefly seen in
the post-breeding
dispersal area.
Adult male
present and
foraging.
Nest #1 empty and nesting
territory abandoned. Four
birds, including at least one
adult (male), found in the
6/24 post-breeding
dispersal area. Up to three
separate birds found
approximately 250 meters
to the east. Possibly more
Territory #5 dispersal.
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Coastal California Gnatcatcher and Cactus Wren Focused Survey Results
A total of five (5) CACW territories were mapped during the focused surveys (refer to Figure 5, Cactus
Wren Results, in Attachment A). No attempts were made to find CACW nests, although one (1) nest was
incidentally found outside of any apparently active territories. Although no nests were found in the
territories, all five territories fledged young. Of these, Territory #5 is the only one that had an obvious
instance of post-breeding dispersal into a new area during the surveys, with all other families utilizing the
same territories that they had evidently nested in. A more detailed summary of CACW activity in each
territory during each survey is provided in Table 3 below.
Table 3: CACW Survey Results
Date Territories
Territory #1 Territory #2 Territory #3 Territory #4 Territory #5
5/26/20 Adult pair
present.
Independent
juvenile bird to
the west either
from Territory
#1 or Territory
#3.
Adult male
singing.
Adult pair
present.
Adult pair with
two juveniles
present.
One bird heard only.
Cooper’s hawk
suppressed activity.
6/3/20 Adult pair
present.
Independent
juvenile bird to
the west either
from Territory
#1 or Territory
#3.
Adult male
singing.
Adult bird
present.
At least three
birds present.
Food exchange
witnessed
between adult
and one of the
juveniles.
One bird heard only.
Cooper’s hawk
suppressed activity.
6/10/20 Two adults
present.
Three adults
and one
juvenile
present.
Adult male
singing.
Two adults and
two juveniles
present.
Two adults and two
juveniles present
together.
6/17/20 Two adults and
three juveniles
present.
Two adults and
two juveniles
present.
Adult male
singing.
At least four
birds present.
Family unit moved
slightly north to a post-
breeding dispersal area.
6/24/20 One bird present,
did not take
notes on age.
Three birds
present, did not
take notes on
age.
Two adults
present.
Five birds
present
together.
All four birds seen
together in the post-
breeding dispersal area.
7/1/20 Two adults seen
in territory.
All four birds
seen in
territory.
One adult with
two juveniles
observed. First
evidence of
nesting.
Five birds
present in a
group together.
No birds found in the
post-breeding dispersal
area. Two adults and one
juvenile found in the
original territory.
Conclusions and Recommendations
Based on the results of the focused surveys, at least five (5) CAGN and five (5) CACW territories were
found to be present within the 500-foot survey area. Four (4) CAGN pairs and all five (5) CACW pairs
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successfully fledged young in 2020 as evidenced by firsthand observations by Michael Baker biologists
during the surveys. Many of the territories were directly adjacent to, crossed over, or were at least in close
proximity to proposed trail improvement areas. Of the nests that were found, the closest nest (CAGN
Territory #2 Nest #1) was approximately 70 feet from the Canyon Loop Trail.
Although a variety of trail improvements are proposed for this project, most of the improvements are
widening the existing trail in the southern half of the survey area. This would result in loss of suitable
habitat for these species, particularly for CAGN. Based on project plans, the length of proposed trail
widening is currently estimated at approximately 1,942 feet, or approximately 0.37 mile. The trail is
proposed to be widened to five feet total width, which means on average based on field observations during
the surveys it would be widened an additional one to two feet from its current width at these locations. The
on-site CACW is not believed to be the sensitive CCACW protected by the CDFW as a SSC; regardless,
impacts to this species can be addressed through a nesting bird clearance survey (see below), with additional
benefits imparted via CAGN protections. Although this area is not designated as Critical Habitat, loss of
vegetation directly supporting known populations of CAGN would constitute “take” of CAGN under
Section 9 of the FESA. Because the project will not have a Federal nexus to allow for FESA Section 7
consultations, an incidental take permit (ITP) would instead be granted by the USFWS under Section
10(a)(1)(B) of the FESA. This typically entails the project proponent agreeing to a habitat conservation
plan (HCP), an extensive process that can take years to complete. However, the USFWS also has a category
of HCPs for projects that will otherwise have minor impacts on listed species, called a “low-effect HCP.”
These HCPs pertain to projects involving (1) minor or negligible effects on federally listed, proposed, or
candidate species and their habitats covered under the HCP; and (2) minor or negligible effects on other
environmental values or resources. Under low-effect HCPs, the permitting process is more streamlined and
take can generally be authorized under a series of strict avoidance and minimization measures. Therefore,
it is recommended that the City consult with USFWS and pursue a low-effect HCP to permit removal of
habitat suitable for and/or used by CAGN on the project site.
To avoid indirect impacts and take of CAGN or CACW, it is recommended that all project-related
construction occur outside of the general breeding season (February 15 – September 15). Timing the
construction to be outside of this window of time would avoid impacts to CAGN or CACW nests. If it is
not possible to construct the project outside of this time period, it is recommended that a nesting bird survey
be conducted within seven (7) days prior to the start of construction in a 500-foot buffer from the project.
The survey should be conducted by a qualified biologist with demonstrable experience identifying CAGN
and CACW nesting behavior and finding their nests, and who has been approved by the USFWS to conduct
a CAGN nesting survey. If an active CAGN or CACW nest is found during the survey, no project-related
construction will be allowed within 500 feet of an active CAGN nest or 300 feet of an active CACW nest,
or within an alternative safe distance as determined by the qualified biologist based on topography, visual
shielding, nest progress, and the type of construction and associated disturbance, until the active nest has
been determined by the qualified biologist to have failed or to have successfully gone to completion (i.e.
the nestlings have fledged and are no longer reliant on the nest). Results of the nesting bird survey, should
one be required, shall be compiled in a memorandum and submitted to the City and to the USFWS for the
project record.
Please do not hesitate to contact me at (949) 533-0918 or ryan.winkleman@mbakerintl.com should you
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have any questions or require further information regarding the information presented in this report.
Sincerely,
Ryan Winkleman
Senior Biologist
Natural Resources and Regulatory Permitting
Attachments:
A. Figures
B. Site Photographs
C. Wildlife Species Observed List
D. References
Attachment A
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LOS ANGELES COUNTY
ORANGE COUNTY
Regional Vicinity
Figure 1
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Miles7/30/2020 JN H:\pdata\178669\GIS\MXD\Focused Bird Surveys\Fig 01 Regional Vicinity.mxd RPCANYON LOOP TRAIL IMPROVEMENT PROJECT
COASTAL CALIFORNIA GNATCATCHER AND CACTUS WREN FOCUSED SURVEY RESULTS
Source: ArcGIS Online, 2018
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34.007148-117.794138
34.000846-117.805472
Survey Area7/30/2020 JN H:\pdata\178669\GIS\MXD\Focused Bird Surveys\Fig 02 Survey Area.mxd RPSource: Nearmap, 2020 Figure 2
0 270135
Feet
CANYON LOOP TRAIL IMPROVEMENT PROJECT
COASTAL CALIFORNIA GNATCATCHER AND CACTUS WREN FOCUSED SURVEY RESULTS
°
Legend
Project Site
Survey Area
(Suitable Habitat
within 500 Feet)"Photograph Point
and Direction
!>Reference Point
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GrubstakeDrMeanderingCreekDr
SummitridgeDr34.007148-117.794138
34.000846-117.805472
Vegetation Communities7/30/2020 JN H:\pdata\178669\GIS\MXD\Focused Bird Surveys\Fig 03 Vegetation Communities.mxd RPSource: Nearmap, 2020 Figure 3
0 270135
Feet
CANYON LOOP TRAIL IMPROVEMENT PROJECT
COASTAL CALIFORNIA GNATCATCHER AND CACTUS WREN FOCUSED SURVEY RESULTS
°
Legend
Project Site
Survey Area
(Suitable Habitat
within 500 Feet)
California Buckwheat
Scrub (0.45 acre)
California Sagebrush -
Black Sage Scrub
(2.13 acres)
Coast Prickly Pear
Scrub (9.90 acres)
Disturbed California
Sagebrush - Black
Sage Scrub
(17.76 acres)
Unnamed Drainage
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Nest #2
Nest #3
Nest #1
34.007148-117.794138
34.000846-117.805472
Coastal California Gnatcatcher Results8/4/2020 JN H:\pdata\178669\GIS\MXD\Focused Bird Surveyst\Fig 04 Coastal California Gnatcatcher Results.mxd RPSource: Nearmap, 2020 Figure 4
0 270135
Feet
CANYON LOOP TRAIL IMPROVEMENT PROJECT
COASTAL CALIFORNIA GNATCATCHER AND CACTUS WREN FOCUSED SURVEY RESULTS
°
Legend
Project Site
Survey Area
(Suitable Habitat
within 500 Feet)
!>Reference Point
CAGN Territories
Territory #1
Territory #2
Territory #3
Territory #3
(Post-breeding
Dispersal)
Territory #4
Territory #5
Territory #5
(Post-breeding
Dispersal)
CAGN Nests
!(Successful Nest
!(Failed Nest
Proposed Trail Improvements
Trail to be Expanded
to 5' Wide
Existing Trail to Remain
Gabion Retaining Wall
Stairs
kj Wayfinding Sign
Lodge Pole Fence
(Shade Structure with
Benches & Trash Receptacle
Proposed Bench
Drainage Crossing
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6/3/20
34.007148-117.794138
34.000846-117.805472
Cactus Wren Results8/4/2020 JN H:\pdata\178669\GIS\MXD\Focused Bird Surveyst\Fig 05 Cactus Wren Results.mxd RPSource: Nearmap, 2020 Figure 5
0 270135
Feet
CANYON LOOP TRAIL IMPROVEMENT PROJECT
COASTAL CALIFORNIA GNATCATCHER AND CACTUS WREN FOCUSED SURVEY RESULTS
°
Legend
Project Site
Survey Area
(Suitable Habitat
within 500 Feet)
!>Reference Point
CACW Territories
Territory #1
Territory #2
Territory #3
Territory #4
Territory #5
Territory #5
(Post-breeding
Dispersal)
CACW Nests
!(Old Nest
CACW Observations
!(Solitary Juvenile
Proposed Trail Improvements
Trail to be Expanded
to 5' Wide
Existing Trail to Remain
Gabion Retaining Wall
Stairs
kj Wayfinding Sign
Lodge Pole Fence
(Shade Structure with
Benches & Trash Receptacle
Proposed Bench
Drainage Crossing
!(!(
Attachment B
Site Photographs
Attachment B – Site Photographs
Canyon Loop Trail Improvement Project B-1
Coastal California Gnatcatcher and Cactus Wren Focused Survey Results
Photograph 1: Standing in coastal California gnatcatcher (CAGN) Territory 1 facing
east-northeast.
Photograph 2: Standing in the CAGN Territory 2 facing south-southeast.
Attachment B – Site Photographs
Canyon Loop Trail Improvement Project B-2
Coastal California Gnatcatcher and Cactus Wren Focused Survey Results
Photograph 3: Standing in CAGN Territory 2 facing southwest. This is the most
highly-disturbed CAGN territory within the survey area.
Photograph 4: Standing in CAGN Territory 2 facing northeast.
Attachment B – Site Photographs
Canyon Loop Trail Improvement Project B-3
Coastal California Gnatcatcher and Cactus Wren Focused Survey Results
Photograph 5: Standing in CAGN Territory 3 facing southeast.
Photograph 6: Standing in CAGN Territory 3 facing west.
Attachment B – Site Photographs
Canyon Loop Trail Improvement Project B-4
Coastal California Gnatcatcher and Cactus Wren Focused Survey Results
Photograph 7: Standing in CAGN Territory 4 facing southeast.
Photograph 8: Standing in CAGN Territory 4 facing southwest.
Attachment B – Site Photographs
Canyon Loop Trail Improvement Project B-5
Coastal California Gnatcatcher and Cactus Wren Focused Survey Results
Photograph 9: Standing in CAGN Territory 5 facing northeast.
Photograph 10: Standing in CAGN Territory 5 facing west.
Attachment B – Site Photographs
Canyon Loop Trail Improvement Project B-6
Coastal California Gnatcatcher and Cactus Wren Focused Survey Results
Photograph 11: Facing west toward cactus wren (CACW) Territory 1.
Photograph 12: Facing north toward CACW Territory 2.
Attachment B – Site Photographs
Canyon Loop Trail Improvement Project B-7
Coastal California Gnatcatcher and Cactus Wren Focused Survey Results
Photograph 13: Standing in CACW Territory 3 facing south.
Photograph 14: Standing in CACW Territory 4 facing west.
Attachment B – Site Photographs
Canyon Loop Trail Improvement Project B-8
Coastal California Gnatcatcher and Cactus Wren Focused Survey Results
Photograph 15: Facing northeast toward CACW Territory 5.
Photograph 16: An adult male CAGN acts aggressively toward a lone juvenile CACW
in CAGN Territory #2.
Attachment B – Site Photographs
Canyon Loop Trail Improvement Project B-9
Coastal California Gnatcatcher and Cactus Wren Focused Survey Results
Photograph 17: A CACW family gathers together in CACW Territory 5.
Photograph 18: An adult male CAGN brings food for the waiting nestlings in Territory
5 Nest #1.
Attachment C
Wildlife Species Observed List
Attachment C –Wildlife Species Observed List
Canyon Loop Trail Improvement Project C-1
Coastal California Gnatcatcher and Cactus Wren Focused Survey Results
Table C-1: Wildlife Species Observed List
Scientific Name* Common Name Special-Status Rank**
Reptiles
Aspidoscelis tigris stejnegeri coastal whiptail SSC
Coluber flagellum piceus red racer
Sceloporus occidentalis longipes Great Basin fence lizard
Uta stansburiana elegans western side-blotched lizard
Birds
Accipiter cooperii Cooper’s hawk WL
Aeronautes saxatalis white-throated swift
Aimophila ruficeps canescens southern California rufous-crowned sparrow WL
Aphelocoma californica California scrub jay
Baeolophus inornatus oak titmouse
Buteo jamaicensis red-tailed hawk
Callipepla californica California quail
Calypte anna Anna’s hummingbird
Campylorhynchus brunneicapillus cactus wren
Cathartes aura turkey vulture
Chamaea fasciata wrentit
Contopus sordidulus western wood-pewee
Corvus brachyrhynchos American crow
Corvus corax common raven
Dryobates nuttallii Nuttall’s woodpecker
Empidonax difficilis pacific-slope flycatcher
Geococcyx californianus greater roadrunner
Haemorhous mexicanus house finch
Icterus cucullatus hooded oriole
Leiothlypis celata orange-crowned warbler
Melanerpes formicivorus acorn woodpecker
Melozone crissalis California towhee
Mimus polyglottos northern mockingbird
Molothrus ater brown-headed cowbird
Myiarchus cinerascens ash-throated flycatcher
Patagioenas fasciata band-tailed pigeon
Petrochelidon pyrrhonota cliff swallow
Phainopepla nitens phainopepla
Pipilo maculatus spotted towhee
Polioptila caerulea blue-gray gnatcatcher
Polioptila californica californica coastal California gnatcatcher FT/SSC
Psaltriparus minimus bushtit
Sayornis nigricans black phoebe
Sayornis saya Say’s phoebe
Selasphorus sasin Allen’s hummingbird
Attachment C –Wildlife Species Observed List
Canyon Loop Trail Improvement Project C-2
Coastal California Gnatcatcher and Cactus Wren Focused Survey Results
Table C-1: Wildlife Species Observed List
Scientific Name* Common Name Special-Status Rank**
Sitta carolinensis white-breasted nuthatch
Spinus lawrencei Lawrence’s goldfinch
Spinus psaltria lesser goldfinch
Stelgidopteryx serripennis northern rough-winged swallow
Thryomanes bewickii Bewick’s wren
Toxostoma redivivum California thrasher
Troglodytes aedon house wren
Turdus migratorius American robin
Tyrannus verticalis western kingbird
Tyrannus vociferans Cassin’s kingbird
Vireo huttoni Hutton’s vireo
Zenaida macroura mourning dove
Mammals
Neotoma sp. woodrat
Odocoileus hemionus mule deer
Otospermophilus beecheyi California ground squirrel
Sciurus niger* eastern fox squirrel
Sylvilagus audubonii desert cottontail
* Non-native species
** Special-Status Rank
FT Federally Threatened
SSC Species of Special Concern – any species, subspecies, or distinct population of fish, amphibian, reptile, bird,
or mammal native to California that currently satisfies one or more of the following criteria:
- is extirpated from California or, in the case of birds, in its primary seasonal or breeding role;
- is listed as Federally-, but not State-, threatened or endangered; meets the State definition of
threatened or endangered but has not formally been listed.
- is experiencing, or formerly experienced, serious (noncyclical) population declines or range
retractions (not reversed) that, if continued or resumed, could qualify it for State threatened or
endangered status; or
- has naturally small populations exhibiting high susceptibility to risk from any factor(s), that if
realized, could lead to declines that would qualify it for State threatened or endangered status.
WL Watch List - taxa that were previously designated as “Species of Special Concern” but no longer merit that
status, or which do not yet meet SSC criteria, but for which there is concern and a need for additional
information to clarify status.
Attachment D
References
Attachment D – References
Canyon Loop Trail Improvement Project D-1
Coastal California Gnatcatcher and Cactus Wren Focused Survey Results
Benson, T.A. 2020. Personal communication regarding the regional status of coastal California gnatcatcher
and cactus wren. California State University at San Bernardino, Instructional Support Technician.
July 21, 2020.
California Department of Fish and Wildlife (CDFW). 2020. RareFind 5, California Natural Diversity Data
Base, California. Data base report on threatened, endangered, rare or otherwise sensitive species
and communities for Los Angeles, San Bernardino, and Orange Counties.
eBird. 2020. eBird: An online database of bird distribution and abundance [web application]. eBird, Cornell
Lab of Ornithology, Ithaca, New York. Accessed online at: http://www.ebird.org.
Hamilton Biological. 2019. CEQA Review, Canyon Loop Trail Project, City of Diamond Bar. Submitted to
the City of Diamond Bar. October 14, 2019.
Holland, R. 1986. Preliminary Descriptions of the Terrestrial Natural Communities of California.
Rea, A.M. and K.L. Weaver. 1990. The Taxonomy, Distribution, and Status of Coastal Cactus Wrens.
Western Birds 21(3): 81-126.
Sawyer, J.O., Keeler-Wolf, T., and J. Evens. 2009. A Manual of California Vegetation (Second Edition).
California Native Plant Society, Sacramento, California, USA.
Shuford, W. D., and Gardali, T., editors. 2008. San Diego Cactus Wren. In California Bird Species of
Special Concern: A ranked assessment of species, subspecies, and distinct populations of birds of
immediate conservation concern in California. Studies of Western Birds 1. Western Field
Ornithologists, Camarillo, California, and California Department of Fish and Game, Sacramento.
U.S. Department of Agriculture, Natural Resources Conservation Service (USDA). 2020. Custom Soil
Resource Report for Los Angeles County, California, Southeastern Part. Accessed online at:
http://websoilsurvey.nrcs.usda.gov/app/.
U.S. Fish and Wildlife Service (USFWS). 1997. Coastal California Gnatcatcher (Polioptila californica
californica) Presence/Absence Survey Guidelines. February 28, 1997.
U.S. Fish and Wildlife Service (USFWS). 2007. Endangered and Threatened Wildlife and Plants; Revised
Designation of Critical Habitat for the Coastal California Gnatcatcher (Polioptila californica
californica). Federal Register 72(243): 72010-72213.
U.S. Fish and Wildlife Service (USFWS). 2010. Coastal California Gnatcatcher (Polioptila californica
californica) 5- Year Review: Summary and Evaluation. Accessed online at:
https://www.fws.gov/carlsbad/SpeciesStatusList/5YR/20100929_5YR_CAGN.pdf.
U.S. Geological Survey. 1981. San Dimas, California 7.5-Minute Topographic Quadrangle Map.
xeno-canto. 2020. xeno-canto: sharing bird sounds from around the world. Accessed online at:
http://www.xeno-canto.org.