2169-G East Francisco Blvd., San Rafael, CA 94702 (415) 454-8868 tel info@wra-ca.com www.wra-ca.com

Burrowing Owl Survey Report

YOUNG RANCH SANTA CLARA COUNTY, CALIFORNIA

Prepared For:

YCS Investments 170 Maiden Lane Suite 800 San Francisco, California 94108

WRA Contact:

Geoff Smick smick@wra-ca.com

Date: December 2014

WRA Project Number: 17082

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TABLE OF CONTENTS

1.0 INTRODUCTION ................................................................................................................. 1 1.1 Background and Summary ........................................................................................... 1

2.0 METHODS ........................................................................................................................... 1

3.0 RESULTS ............................................................................................................................ 2 3.1 Site Description ................................................................................................................ 2 3.2 Burrowing Owl Background ............................................................................................. 2

3.2.1 Natural History .......................................................................................................... 2 3.2.2 Regional Information and Santa Clara Valley Habitat Plan ........................................ 7

3.3 Habitat Assessment and Burrow Survey .......................................................................... 7 3.4 Burrowing Owl Surveys ................................................................................................... 8

4.0 IMPACT ASSESSMENT .................................................................................................... 13

5.0 MITIGATION ...................................................................................................................... 14

6.0 SUMMARY AND CONCLUSIONS ..................................................................................... 14

7.0 LITERATURE CITED ......................................................................................................... 15

LIST OF FIGURES AND TABLES

Figure 1. Young Ranch Site Location Map ................................................................................ 3 Figure 2. Biological Communities within the Site ....................................................................... 4 Figure 3. Burrowing Owl Survey Transect Routes ..................................................................... 5 Figure 4. Burrowing Owl Habitat and Occurrences .................................................................... 9 Figure 5. Proposed Development Plan .....................................................................................10 Figure 6. Burrowing Owl Habitat Impacts .................................................................................11

Table 1. 2012 Burrowing Owl Protocol-Level Survey Data ........................................................ 8

APPENDIX

Appendix A – Representative Site Photographs

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1.0 INTRODUCTION

WRA, Inc. (WRA) conducted an analysis to assess the suitability of habitat at Young Ranch (Study Area) for supporting burrowing owl (BUOW; Athene cunicularia). This analysis included California Department of Fish and Wildlife (CDFW; formerly the California Department of Fish and Game, CDFG) protocol-level surveys for BUOW conducted by WRA biologists in April, May, and June of 2012.

This report describes the methods and results of the literature review, site assessment, and protocol-level surveys used to assess the Study Area for (1) the presence and distribution of potential BUOW habitat; (2) the presence and distribution of BUOW individuals; and (3) evidence of prior occurrences of BUOW on the site. These studies were designed to capture as much information as possible on BUOW habitat suitability and the presence or absence of BUOW at Young Ranch during the 2012 breeding season.

Young Ranch is an approximately 2,150-acre ranch located in eastern Santa Clara County, California (Figure 1). The site is situated on Coyote Ridge, east of Highway 101 and between Silver Creek Valley Road to the north and Metcalf Road to the south. The Study Area is predominantly grazed ranching land dominated by non-native annual grassland and serpentine bunchgrass grasslands with pockets of oak woodland and riparian vegetation occurring along drainages and scrub communities occurring on scattered, steep, south-facing slopes.

1.1 Background and Summary

Prior to initiating the protocol-level surveys for BUOW, WRA performed a variety of other biological surveys at Young Ranch. From 2008 to 2014, WRA conducted surveys for the Federal Threatened Bay checkerspot butterfly (BCB; Euphydryas editha bayensis) during the species’ flight season in March and April. From 2008 to 2014, WRA biologists also conducted: rare plant surveys, invasive weed mapping, a wetland delineation, and a tree inventory throughout much of the Study Area. The biologists who conducted this fieldwork noted species incidentally observed during each site visit, and they documented the presence of BUOW adults on the property in early spring (March) during four of the past seven years of field work. However, no BUOW adults or fledglings have been observed on the site during extensive fieldwork conducted during April through July in any of the past seven years. Further, no BUOW were detected during the 2012 protocol-level surveys. Therefore, WRA has determined that the site provides potential overwintering habitat for BUOW, but does not provide suitable nesting habitat.

2.0 METHODS

The BUOW habitat assessment and surveys followed protocols described in the 2012 CDFG Staff Report on Burrowing Owl Mitigation (CDFG 2012). A search of the California Natural Diversity Database (CNDDB; CDFG 2011) for BUOW occurrences in the vicinity of the Study Area was performed using the San Jose East, Lick Observatory, Morgan Hill, and Santa Teresa Hills 7.5-minute USGS quadrangles. Literature reviewed included the BUOW species profiles found in the California Bird Species of Special Concern (Gervais et al. 2008), the Draft Santa Clara Valley Habitat Plan (ICF International 2010), and eBird (2012). A habitat assessment was performed as part of a Biological Resources Assessment prepared for the site (WRA 2011) in which biological communities and potential burrow sites were mapped; this mapping was refined by WRA during the course of subsequent studies at the site between 2011 and 2014 (Figure 2).

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Following the initial habitat assessment, WRA developed a series of “wandering transects” (sensu Pollard 1977) that provided thorough coverage of the site. These wandering transects were chosen as an alternative to the straight-line transect method due to the expansive size of the Study Area (2,150 acres). Three wandering transects which focused on the northwestern portion of the Study Area (i.e., the proposed development area and buffer of 500 feet per CDFW survey guidelines) were created using information gathered during the initial habitat assessment (Figure 3). Transects 1, 2 and 4 were walked during BUOW surveys which were conducted during the BUOW breeding season in 2012. In addition, Transects 1 through 5 were walked during each of the spring BCB surveys conducted by WRA from 2008 through 2014. During the BUOW walking surveys, qualified biologists searched visually with binoculars, listened for BUOW calls, and recorded all potential burrows and BUOW signs (pellets, whitewash, prey remains, or decoration). During the BCB surveys, biologists noted any incidental observations of BUOW individuals and/or BUOW signs.

3.0 RESULTS

3.1 Site Description

The Study Area, containing approximately 2,150 acres, is located along Coyote Ridge, the westernmost ridge of the Mt. Hamilton Range. The Study Area is situated east of Highway 101, between Silver Creek Valley Road to the north and Metcalf Road to the south. The site contains predominantly grazed ranching lands dominated by non-native annual grassland (occupying approximately 60 percent of the site) and native serpentine bunchgrass grassland (occupying approximately 30 percent of the site), with pockets of oak woodland and riparian vegetation along drainages and creeks and scattered patches of scrub habitat on steep, south-facing slopes. Site elevations range from approximately 400 to 1,200 feet National Geodetic Vertical Datum (NGVD), and site topography is composed of rolling hills, level floodplains, steep grassy slopes, and rocky outcrops. Soils throughout the site are primarily undisturbed, native soils, including many areas underlain and influenced by the presence of serpentine bedrock. The site is located within the Coyote Creek watershed and is drained by Silver Creek to the northeast and by Coyote Creek to the south and west. Sources of hydrology within the site include rainfall, natural hillside seeps, and Silver Creek, which is a perennial stream.

3.2 Burrowing Owl Background

3.2.1 Natural History

Burrowing owl occurs in grasslands, desert floors, and other dry, open habitats with sparse to nonexistent tree or shrub canopies and low herbaceous vegetation. Preferred habitat in California includes relatively flat grassland or level to rolling hills (Haug et al. 1993, Small 1994). The species is mostly resident in California, although seasonal movements of residents occur in many areas, and birds from outside the state also overwinter in California (Small 1994, Gervais et al. 2008). Burrowing owl is dependent upon mammals to provide the burrows that are characteristically used for roosting and nesting. In California, BUOW is strongly associated with ground squirrel (Otospermophilus spp.) burrows, although burrows of other mammal species may also be used (Ronan 2002, as cited in Gervais et al. 2008). Additionally, BUOW occurs in human-modified habitats, occupying culverts, canals, and roadsides in agricultural areas and

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Figure 1.Location Map

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Young Ranch Site (2,150 acres)

Biological Communities:California Non-Native Annual Grassland (1,273 acres)

Serpentine Bunchgrass Grassland (675 acres)

Diablan Sage Scrub (98 acres)

Mixed Oak Woodland (55 acres)

Mixed Riparian Woodland (22 acres)

Seasonal Wetland (18 acres)

Developed (5 acres)

Riverine (2 acres)

Pond (1 acre)

Coastal and Valley Freshwater Marsh (1 acre)

Young RanchSanta Clara County,

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Figure 2.Biological Communities

within the Site

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Transect 1 (5.8 miles)

Transect 2 (5.3 miles)

Transect 3 (4.9 miles)

Transect 4 (5.7 miles)

Transect 5 (5.9 miles)

Young RanchSanta Clara County,

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Figure 3.Burrowing Owl Survey

Transect Routes

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airports (Coulombe 1971, Thomsen 1971), and anthropogenic structures such as rubble piles or old pipes in developed areas (Rosenberg et al. 1998, as cited in Gervais et al. 2008). Green and Anthony (1989) reported that vegetation greater than approximately 10 inches was likely to restrict visibility of these owls, rendering the habitat less suitable. Burrowing owl use elevated perches such as larger shrubs and fence posts for foraging (Thomsen 1971, Martin 1973) and the regulation of body temperature (Coulombe 1971). With the exception of nesting females, BUOW are typically conspicuous, and birds are often observed perching outside of burrow entrances, especially in early morning and late afternoon (Haug et al. 1993). Burrowing owl generally exhibits high site fidelity, with birds using the same burrow or set of burrows for nesting across subsequent years (Gervais et al. 2008). When breeding, males are responsible for maintaining territories and food provisioning, whereas females incubate eggs and brood offspring (Thomsen 1971, Martin 1973). Clutch size is relatively large, averaging seven eggs in California, although fewer young are typically fledged (Haug et al. 1993). Prior to fledging, BUOW offspring as young as two weeks old often emerge from burrows and perch near the entrances in the manner of adults (Thomsen 1971, Martin 1973). Although BUOW is often visible and sometimes active during the day, it is generally nocturnal and crepuscular (i.e., active at twilight) in terms of foraging (Thomsen 1971, Haug and Oliphant 1990). Insects and other arthropods provide most of the diet, with a variety of small vertebrates also consumed. Most foraging occurs within 1,970 feet (600 meters) of nest sites, although it can occur up to 1.7 miles (2.7 kilometers) from the nest (Haug et al. 1993).

3.2.2 Regional Information and Santa Clara Valley Habitat Plan

The two closest (0.6 and 0.8 mile) previously documented BUOW occurrences documented in the CNDDB occurred during the non-breeding season and were documented 12 and 22 years ago, respectively (CDFG 2011). More recent (2008) observations documented in the CNDDB are from over 2 miles away from the Study Area. This is comparable with findings in the Santa Clara Valley Habitat Plan (SCVHP) which addresses BUOW conservation within the Santa Clara Valley and surrounding areas (ICF International 2010). The SCVHP divides the Santa Clara Valley into four BUOW conservation regions. Young Ranch falls within the lowest priority BUOW conservation region: South San Jose. This region has a low number of nesting BUOW, and typically only has 0 to 2 nesting adult BUOW in the region (ICF International 2010).

3.3 Habitat Assessment and Burrow Survey

In 2008, WRA identified and mapped vegetation communities (following a combination of Holland 1986 and ICF International 2010) within the Study Area (Figure 2; WRA 2011). Vegetation communities that provide suitable BUOW habitat include non-native annual grassland and serpentine bunchgrass grassland with a slope of 45 percent or less, which totals approximately 1,810 acres, or 94 percent of the Study Area (Figure 4). Both vegetation communities are dominated by non-native and native grasses with few shrubs and trees. These communities are also favored by ground squirrels (and other burrowing mammals), a crucial habitat element for BUOW.

Although much of the Study Area contains vegetation communities with potential BUOW, there are very few suitable burrow complexes in the Study Area; this limits the potential for BUOW occupation. The serpentine grassland in the southeast is considered the most suitable habitat because of its shorter grass height in the spring months and higher density of rock outcrops and jumbles. In spring, the non-native annual grassland which dominates the northern two-thirds of the Study Area supports grasses that can reach heights greater than 20 inches, making these areas less suitable for BUOW (Green and Anthony 1989). The reduced occurrence of rock

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outcrops and jumbles in the northern portion of the Study Area also reduces habitat suitability there. Several ground squirrel burrow complexes were observed in the north-central part of the Study Area; however, BUOW were typically not observed in or near these complexes during surveys (Figure 4).

3.4 Burrowing Owl Surveys

Protocol-level surveys were conducted during the peak of the BUOW breeding season on the mornings of April 16, May 16, May 30, and June 27, 2012. All surveys occurred during suitable weather conditions and time of day for increased detection probabilities (Table 1). The wandering transects followed during the surveys are shown on Figure 3, and photographs of the Study Area are provided in Appendix A. Biologists experienced with identification of BUOW signs and habitat performed the surveys, including Jason Yakich, Kate Allan, Rob Schell, Daniel Chase, Dana Riggs, Bill Stagnaro, Jeff Dreier, Spencer Badet, and Patricia Valcarcel. No BUOW were observed within the Study Area during any of the survey efforts. No obvious owl signs were observed near burrow entrances, which were carefully examined on each day of surveys. Grass height was relatively low in areas of serpentine grassland due to cattle grazing, which resulted in high visibility over long distances. Areas of non-native annual grassland in the northern portion of the Study Area contained grasses greater than 20 inches tall, reducing visibility (and thus BUOW suitability) in these areas. Additionally, WRA biologists walked these (and other) transects annually in March and April between 2008 and 2014 while surveying for BCB. During these surveys, any BUOW observations were also recorded (Figure 4). Burrowing owl was observed in several locations within the Study Area in four of the seven years of BCB surveys; however, during surveys conducted at the site for other biological resources (e.g., rare plant surveys, weed mapping, etc.) in late spring and/or summer of each year, neither adults nor fledglings were detected. Based on survey results, it appears that the individuals observed in early spring were overwintering owls that migrated elsewhere to breed. Therefore, WRA believes that the Study Area is likely to be used by BUOW only seasonally as overwintering and foraging habitat. Table 1. 2012 Burrowing Owl Protocol-Level Survey Data

Date Start time Stop time Percent cloud cover

Temperature (˚F) at start

time Wind

Number of BUOW observed

April 16 1010 1440 0 61 Light breeze 0

May 16 0735 1030 10 60 Calm 0

May 30 0745 1030 0 60 Calm 0

June 27 0845 1110 0 65 Calm 0

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Figure 4.Burrowing Owl

Habitat and Occurrences

Young Ranch SiteBurrowing Owl Habitat (1,810.1 acres)Burrow Complexes

Burrowing Owl Observances2009 Occurrence2011 Occurrences2013 Occurrences2014 Occurrences

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Figure 5. Proposed

Development Plan

Young Ranch SiteLimits of Impact Homesites

Managed Grasslands

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Figure 6.Burrowing Owl Habitat Impacts

Young Ranch SiteYoung Ranch Community Plan500' Burrowing Owl Potential Disturbance Buffer Burrow ComplexesBurrowing Owl Habitat Impact (192.2 acres) Burrowing Owl Habitat Preservation (1,617.9 acres)

Burrowing Owl Observances2009 Occurrence2011 Occurrences2013 Occurrences2014 Occurrences

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4.0 IMPACT ASSESSMENT

Based on the habitat assessment, protocol-level surveys, and other incidental observations, WRA concludes that the Study Area does not support any BUOW breeding habitat and therefore, no direct or indirect impacts to breeding habitat would occur as a result of the proposed development of the community and natural preserve on the site. The proposed Project involves construction of 79 residential lots, a Community Center, and attendant infrastructure. A small portion of land within the development will be preserved and managed as open grassland (“Managed Grasslands”). Site areas that are not included within the development footprint will be permanently protected as a natural preserve (“Conservation Lands”). As described in the Design Guidelines prepared by Cultivate (2014) and the Resource Management Plan prepared by WRA (2014), each lot will contain an approximately 1-acre development envelope (“Private Area” and “Transition Area”) and an approximately 1-acre area to be managed as open grassland (“Natural Area”). The Community Center will have a development footprint of 21,000 square feet (approximately 0.4 acre); the remaining portion of the Community Center lot will also be managed as open grassland. The Project footprint, including the Managed Grasslands and Conservation Lands are shown on Figure 5. To assess impacts, WRA conservatively considered all parts of the development as impacted, including the Natural Area of each lot and the undeveloped portion of the Community Center lot, even though these areas will receive minimal impacts and will be managed as open grassland.

Impacts associated with the proposed Project would occur in the northwestern portion of the site (Figure 5), in an area where no BUOW have been observed. The proposed Project would result in the loss of approximately 192 acres of potential BUOW overwintering habitat (Figure 6). The impact areas are located almost exclusively in non-native annual grassland, a habitat with low suitability for BUOW due to the high spring grass heights and the relative scarcity of burrows and other structures which can be utilized by BUOW. More suitable habitat with lower grasses, rock outcrops, and squirrel burrows is located in the serpentine bunchgrass grassland in the southeastern portion of the site, outside the limits of disturbance for the proposed Project. Although the impact area for the Project includes three ground squirrel burrow complexes, no BUOW were observed in the vicinity of these features during the protocol-level surveys or during the seven years of BCB surveys in these areas. Therefore, no direct impacts to BUOW individuals are anticipated to occur as a result of the proposed Project. Several owl occurrences were documented within 500 feet of the proposed impact area and could potentially be disturbed if present during construction of the proposed Project. With the implementation of suitable avoidance and minimization measures described below in Section 5.0, no direct or indirect impacts to BUOW are anticipated during construction.

The preservation of high quality BUOW habitat within the serpentine bunchgrass grasslands at the site will provide mitigation for the loss of potential (albeit low quality) BUOW overwintering and foraging habitat. Upon Project completion, approximately 1,618 acres of potential BUOW foraging and overwintering habitat will be preserved and managed according the Resource Management Plan prepared for the site (WRA 2014). Most of this will be in the southeastern part of the site, where majority of observed owls were located. Visibility for owls would not likely be altered from current conditions because the proposed impact area is located in the northern portion of the site. The southern portion of the site will be set aside as a natural preserve with limited public access, isolating the majority of human disturbance to the northern portion of the site, away from the majority of BUOW observations. Therefore, the proposed Project is not expected to have significant impacts on the BUOW population in the region.

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5.0 AVOIDANCE, MINIMIZATION, AND MITIGATION

Measures to ensure avoidance of direct or indirect impacts would start with pre-construction surveys for BUOW within the impact area and a surrounding 250-foot disturbance buffer. Pre-construction surveys would conform to the methods described in the SCVHP (2012). If owls are observed during pre-construction surveys, additional avoidance measures would be implemented to limit or minimize potential impacts and/or disturbance to BUOW in accordance with the SCVHP; these measures are outlined below. If work will be conducted during the BUOW breeding season (February 1 – August 31) and breeding owls are observed during pre-construction surveys, a 250-foot exclusion buffer would be established around active burrows. If it is not feasible to avoid the exclusion area, work could occur if (a) the BUOW nest will not be disturbed and (b) and avoidance, minimization, and monitoring plan will be prepared and will be subject to approval by the SCVHP Implementing Entity and the CDFW. Biological monitoring during construction may be included in this plan, if applicable. If work will occur during the non-breeding season (September 1 – January 31), a similar 250-foot exclusion buffer around occupied burrows will be established. If it is not feasible to avoid the exclusion area, work could occur if a qualified biologist monitors the owl(s) prior to and during construction and finds no change in owl foraging behavior in response to construction activities. If there is a change in foraging behavior, the activities causing the disturbance would cease within the exclusion zone. If, during the non-breeding season, owls are not observed at a burrow for more than one week, a qualified biologist may excavate abandoned burrows with approval from the SCVHP Implementing Entity. With the implementation of these measures from the SCVHP, it is expected that the Project will not result in direct or indirect impacts to BUOW on the site. In total, approximately 192 acres of potential foraging and overwintering BUOW habitat will be impacted within the 2,150-acre site. Approximately 1,618 acres of potential BUOW foraging and overwintering habitat within the Study Area will be set aside as part of the planned preserve. The BUOW overwintering habitat will be grazed and otherwise managed in support of BUOW habitat according to the guidelines presented in the Young Ranch Resource Management Plan (WRA 2014). This represents a mitigation to impact ratio of greater than 7:1.

6.0 SUMMARY AND CONCLUSIONS A habitat assessment revealed that approximately 1,810 acres of the 2,150 acres at Young Ranch provide potential overwintering habitat for BUOW (Figure 4). Protocol-level surveys were performed during the peak breeding season for BUOW, but no BUOW or evidence of BUOW were observed. WRA performed several consecutive seasons of surveys for other sensitive species throughout the site (during March and April from 2008 to 2014, during May, June, and July from 2009 to 2011, and during May 2013); any observations of BUOW during these surveys was noted. The limited number of BUOW observations at the site all occurred in March, and follow-up surveys performed later in the spring and early summer did not detect adult or fledgling BUOW. The lack of detections of BUOW following the breeding season indicates that it is likely that the BUOW observed in March of 2009, 2011, 2013, and 2014 were either migrating or dispersing individuals. Based on these results, WRA concludes that Young Ranch does not support breeding habitat for BUOW, but does provide foraging and overwintering habitat for BUOW. No impacts to breeding habitat would occur as a result of the

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proposed Project. Impacts to 192 acres of potential foraging and overwintering habitat would be offset through onsite habitat preservation of 1,618 acres of potential BUOW overwintering and foraging habitat within the serpentine bunchgrass grassland at the southern portion of the site. With the implementation of recommended avoidance and minimization measures, no direct or indirect impacts to individual BUOW are anticipated to occur as a result of the proposed Project.

7.0 LITERATURE CITED

[CDFG] California Department of Fish and Game. 2012. Staff Report on Burrowing Owl Mitigation. Natural Resources Agency, California Department of Fish and Game. March 2012.

CDFG. 2011. California Natural Diversity Database. Sacramento.

Coulombe, HN. 1971. Behavior and Population Ecology of the Burrowing Owl, Speotyto cunicularia, in the Imperial Valley of California. Condor 73: 162-176.

eBird. 2012. eBird: An online database of bird distribution and abundance [web application]. Version 2. eBird, Ithaca, NY. Available: http://www.ebird.org. Accessed 17 July 2012.

Gervais, JA, DK Rosenberg, and LA Comrack. 2008. Burrowing Owl (Athene cunicularia). In: Shuford , W. D. and T. Gardali, eds. 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.

Green, GA and RG Anthony. 1989. Nesting success and habitat relationships of burrowing owls in the Columbia Basin, Oregon. Condor 91:347-354.

Haug, EA and LW Oliphant. 1990. Movements, Activity Patterns, and Habitat Use of Burrowing Owls in Saskatchewan. Journal of Wildlife Management 54(1): 27-35.

Haug, EA, BA Millsap, and MS Martell. 1993. Burrowing Owl (Athene cunicularia). In: A Poole, ed. The Birds of North America Online. Ithaca: Cornell Lab of Ornithology. Available online: http://bna.cornell.edu/bna/species/061.

Holland RF. 1986. Preliminary Descriptions of the Terrestrial Natural Communities of California. California Department of Fish and Game. October.

ICF International. 2010. Draft Santa Clara Valley Habitat Conservation Plan. December.

Martin, DJ. 1973. Selected Aspects of Burrowing Owl Ecology and Behavior. Condor 75: 446-456.

Pollard, E. 1977. A method for assessing changes in the abundance of butterflies. Biol. Conserv. 12:115-134.

Small, A. 1994. California Birds: Their Status and Distribution. Ibis Publishing Compay. Vista, California.

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Thomsen, L. 1971. Behavior and Ecology of Burrowing Owls on the Oakland Municipal Airport.

Condor 73: 177-192. WRA, Inc. 2011. Biological Resources Assessment Report, Young Ranch, Santa Clara

County, California. Prepared for YCS Investments, San Francisco, California. WRA, Inc. 2014. Draft Resource Management Plan, Young Ranch, Santa Clara County,

California. Report prepared for YCS Investments, San Francisco, California.

Appendix A – Representative Site Photographs

A-1

Top: Young Ranch Study Area, April 2012

Bottom: Young Ranch Study Area, April 2012

A-2

Young Ranch Study Area in April 2012.

Top: Ground squirrel (Otospermophilus beecheyi) burrow

Bottom: Area with an assembly of ground squirrel burrows