140P8522Q0031_Sample_Past_Report_Redacted_0001.pdf

Demographic Survey of the Alameda whipsnake (Masticophis lateralis euryxanthus) on Mt. Wanda at John Muir National Historic Site

Prepared for:

National Park Service John Muir National Historic Site, Martinez, CA

Prepared by:

John Muir National Historic Site

Prepared on:

November/December 2021

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PAST R

EPORT

Project park: John Muir National Historic Site (JOMU), Martinez, CA Project contacts:

Project permit: #

To:

PURPOSE AND OBJECTIVES

In 2021, John Muir National Historic Site continued population monitoring surveys to determine the occurrence of the Alameda whipsnake (Masticophis lateralis euryxanthus) (ALWH) on Mt.

Wanda. National Park Service (NPS) staff collected demographic and morphometric data on captured snakes, and information on how and where ALWH populations were using park resources, with the goal of establishing a long-term ALWH monitoring program at the park and better protecting the species. The ALWH is a federally threatened sub-species of the California whipsnake (Masticophis lateralis) and direct threats to the species include increased human population and urban development which leads to habitat fragmentation and resource loss (USFWS, 2005). The ALWH has a relatively small range, with the current distribution reduced to five populations in Contra Costa and Alameda Counties: Sobrante Ridge (Tilden-Briones, includes Mount Wanda), Oakland Hills, Mount Diablo vicinity and the Black Hills, Hayward Hills, and Wauhab Ridge. When the park began monitoring ALWH in 2017, it was expected that a low number of individuals would be found due to the species restricted range.

This monitoring project has built on previous surveys, conducted in collaboration with The Wildlife Project, Sacramento, CA from 2017-2019. Monitoring conducted in spring and fall 2021 involved additional field surveys for the ALWH in suitable habitat on Mt. Wanda. John Muir NHS has a valid ESA Section 10(a)(1)(A) recovery permit (#TE-43714D-0, exp: 12/09/2024) for conducting research, monitoring, and handling of ALWH. The List of Authorized Individuals (LAI) include , . Additional personnel included

; and , and various park staff. Project provides recommendations, based on data results and analyses, to improve or protect conditions for the ALWH. These recommendations will be included in the Mt. Wanda Comprehensive Site Management Plan currently being developed. In addition, it provides

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current (and future) NPS staff with training, experience, and the capacity to conduct future monitoring to ensure long term monitoring sustainability.

SURVEY METHODS

Study Site

Mt. Wanda is located immediately north of California State Route 4, west of Alhambra Avenue and Alhambra Valley Road, and north or Briones Regional Park in Contra Costa County, CA. The 326-acre site is composed of coastal scrub, mixed oak woodland, and annual grasslands. John Muir NHS is managed for recreational access, historic landscape preservation and natural resource protection. The surrounding habitat is primarily covered by low-density residential housing, and native and invasive grassland and oak woodland mix habitat types.

Site conditions include unpaved access roads and maintained hiking trails. Herbaceous vegetation on the site grows from approximately ground-level to nearly two meters tall (non-native annual grasses). This cover layer ranges from 0% (on open trails) to 100% (primarily grassland cover). Shrub cover is sparse or absent in most of the site, with coyote brush (Baccharis pilularis) in widely scattered clumps (≤ .25 hectares), and small patches of coastal scrub found in two separate locations totaling approximately 0.4 hectares. Oak woodland is the dominant vegetation (i.e., subdominant was non-native annual grasses) which includes coast live oak (Quercus agrifolia), blue oak (Q. douglasii), bay laurel (Umbellularia californica), and associated woodland trees and shrubs. Remaining vegetation includes a small area of cultivated olive tree (Olea europaea), scattered Eucalyptus and other ornamental vegetation. Downed and woody debris is sparse on the site but found in higher concentrations associated with oak woodlands. Slope aspects on the site includes north, south, east, and west slopes, with most of the site having woodland covered slopes facing in a variety of directions. General characterization of the site includes a complex series of hills (up to an elevation of 200 meters) broken up by steep drainages and covered by dense vegetation.

Materials and Methods

Focused surveys in 2021 included a review of herpetological communities, with a target species of the Alameda whipsnake. These reviews were observed and reported on site by NPS employees: : , . ESA Section 10 recovery permit requires at least one LAI be present during all ALWH research, monitoring, and handling. Park staff used survey methods previously established by The Wildlife Project and East Bay Municipal Utilities District biologists during 2021 monitoring. Survey techniques for the ALWH included visual monitoring and drift fence arrays with funnel traps. The timing of surveys considered the snake's natural history and phenology, which displays two annual peaks of high activity levels during the spring mating season, and a smaller second peak during late summer/early fall before the species enters hibernation for the winter.

In 2020, surveys were conducted at two locations on Mt. Wanda and included 5 traplines. These sites were previously described as “hotspots,” with the highest concentration of ALWH captures in 2018. The two sites consisted of chaparral scrub habitat with chamise shrubland and rocky outcrops bordered by mixed oak woodland and annual grasses (traplines 4/5/6), and a historic olive orchard bordered by chamise shrubs and annual grassland (traplines 9/10) (Figure 1). The two monitoring sites consisted of one 0.36-hectare patch of coastal scrub surrounded by oak woodland on a north facing slope, and a second patch that bordered an almost exclusive 0.70-hectare olive orchard on a southeast facing slope. Access to trap locations was by foot.

In 2021, we expanded our survey efforts to include new areas and previously closed traplines. In the spring season, we continued monitoring a “hotspot” area (traplines 4/5/6), and we relocated traplines 9/10 across a fence line, 5 meters into the West Hills property (Figure 2). This area consisted of more chaparral scrub and chamise shrubland habitat, featuring rock outcrops. We re-opened traplines 1/2 in coastal scrub habitat and installed new traplines 11/12 within the West Hills property. Trapline 11 bordered coyote bush and thick poison oak habitat as well as mixed oak woodland and annual grassland. Trapline 12 was placed directly in young olive tree habitat, to test for movement and vegetative structure use as previous trapping success at 9/10 bordered a historic olive orchard. In the fall season, we closed traplines 4/5/6, 9/10 and 12 (Figure 3). We re-opened previously closed traplines 3 and 7/8 (from 2017-2019) which were in mixed oak woodland (with downed woody vegetation) and annual grassland habitat (with poison oak and coyote bush shrubs intermixed).

Each trapline had 50-foot sections of drift fence with Clark funnel traps at the ends—consistent with the California Department of Fish and Wildlife’s (CDFW) 1997 Draft Survey Protocol for Alameda Whipsnake. Traps were checked at least once per day. Each trap had shade structures to provide shelter and cover from predators and heat. Monitoring occurred Monday through Friday in spring between April 19 and July 16 and again for two weeks in fall from September 27 through October 8.

Captured ALWH were identified (sex and species), measured, weighed, uniquely marked with a permanent ventral scute clip, and released at the site of capture. Recapture rates were documented to help determine relative abundance and density. Non-target species were identified, marked with a temporary marker and released on-site.

RESULTS

Six Alameda whipsnakes were captured in 2021. During the spring monitoring period, five individual ALWH were captured, including four adult males and one sub-adult male (Table 1).

One female juvenile individual was captured in the fall monitoring season. The male to female ratio captured this season, follows the pattern of a higher male capture rate since the project began. In spring and early summer, males will travel throughout their home ranges to forage and find mates, while females stay close to their hibernation site, where mating occurs. Females only have a few days of peak activity in the spring when they are looking for suitable egg-laying sites.

This can make their capture less frequent.

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Alameda whipsnakes were encountered at only one of the previously established “hotspot” areas. No ALWH were captured at 4/5/6 (one of the larger coastal scrub areas on Mt. Wanda) and only one ALWH was captured at traplines 9/10 (which was relocated 5 meters over the fence line into coastal shrub habitat and bordering an historic olive orchard). Previous years yielded more individuals at both sites. The other 4 individual ALWH were captured at new and re-opened sites, including trapline 11 and previously closed traplines 1/2 and 8. Alameda whipsnakes were thought to be relatively uncommon and unexpected prior to the beginning of monitoring on Mt. Wanda. Surveys have shown that there is a relatively active and viable population(s) on Mt. Wanda and possibly adjacent areas. Since monitoring began, 39 individuals have been captured (Table 2). ALWH represent 45% of all snakes captured on Mt. Wanda.

In addition to six ALWH, one California king and two California night snakes and one western yellow-bellied racer (first observation of this species on Mt. Wanda) were captured in 2021.

Other non-target species captured in traps included newts, lizards, skinks, rodents, and a single shrew species. Lizards were the most common reptile species captured (n=23) and were comprised of western fence lizard (n=19), western skink (n=3), and southern alligator lizards (n=1). Additionally, 185 mammal species were captured, including brush mouse (n=95), deer mouse (n=47), California mouse (n=1), western harvest mouse (n=12), house mouse (n=3), California vole (n=5) and ornate shrew (n=1). Visual encounters while walking survey routes included pacific gopher snakes, California king snakes, numerous western fence lizards, western skinks, and southern alligator lizards on and alongside trails.

Environmental Variables

The 2018 fall survey season began in late October but ended early due to low temperatures and an increased mortality of non-target species. As a result, the fall 2020 surveys began two and a half weeks earlier and temperatures were higher. In 2021, the fall survey season began in late September and average fall temperatures were higher than 2018 but lower than 2020. (Figure 4 and Table 3). With only 2 ALWH captures in the fall season (2018 and 2021), the short trapping season and risk of increased mortality due to cold weather may not be worth the survey effort.

We will reconsider the value of conducting fall surveys in the future and may investigate less time consuming methods, such as cover board surveys.

CONCLUSION

Although, Mt. Wanda is designated as Critical Habitat for ALWH, there is less than 1 acre of their preferred coastal scrub habitat. However, Alameda whipsnakes use the site with regularity as surveys have shown since 2018. During this particularly dry season, this year’s capture rates were again much lower than 2018, with no recaptures. Capture rate for western fence lizards was also lower in 2021 (lowest in all the project years), but still the most frequently captured species, indicating the habitat is still supporting the main prey species for the ALWH, along with other potential prey (other lizards and small mammals).

Based on previous data collected from 2018-2019, models estimate the population size of ALWH between 30-92 snakes, with a mode (most likely value) of 43 individual snakes using the site. This indicates that there is a viable population using the available habitat on Mt. Wanda, despite the habitat types appearing to be primarily atypical or far too small for the species (Swaim, 1994). It is important that data on the species continue to be collected across multiple years to create a more comprehensive understanding of population demographics, size, and movement.

Based on recapture data, no ALWH were believed to be moving between the olive orchard site and the scrub habitat (1,325 meters) on Mt. Wanda during the survey periods. These two sites are separated by a large expanse of ungrazed non-native grassland, which is interspersed by oak woodlands. It’s unclear what the role of ungrazed grassland might have on the ability of whipsnakes to move through that habitat, but the 2-meter tall grasses make it difficult to navigate. Snakes are unlikely to project direction or distance in such dense vegetation, and structurally, the grasses will not support a semi-arboreal snake that would otherwise climb over the top of the vegetation (Van Denburgh, 1897; Grinnell and Grinnell, 1907; Ortenburger, 1928).

Dense, ungrazed vegetation may in fact be an unforeseen barrier to movement. The USFWS (2002) suggested that cessation of grazing has been implicated in habitat degradation for the species.

Although atypical habitat, Alvarez et al. 2021 suggests that the structure of the olive orchard vegetation may in fact be more critical to whipsnake because it’s similar to native scrub in structure (i.e., brushy, short-stature trees with low over-hanging branches, and clear understory). Additionally, the olive orchard habitat boarders land that includes rocky outcrops, scrub habitat, mixed oak woodlands, and annual grasslands, which the snakes might be using, and suggests ALWH are being captured on the borders of their movement patterns.

It was previously reported by Alvarez et al. (2005) and Swaim (1994), that the species uses scrub/chaparral habitat, but significant numbers of observations were made in adjacent habitats, including grassland, oak woodlands, and other habitats. The population(s) found on Mt. Wanda also imply that the species may not be as restricted as previously reported as the population size is larger than what the “preferred” habitat can support. It appears that individual snakes use a variety of habitats and slopes that allow for aerial basking on vegetative canopies, and suitability increases when lizard, snake, and other prey are available (Alvarez and Murphy, In Review).

In 2021, previously established “hotspot” areas were closed in the fall due to continuous human activity and impact on vegetation in the area due to monitoring. These areas also yielded no or low numbers of ALWH captures. The park was interested in additional movement and habitat use in other areas of the park, so previously closed sites were re-opened, and new sites were established based on potentially preferred habitat and adjacent land use. In 2022, the park will continue monitoring efforts and increase the survey area on newly acquired lands (West Hills Farm) adjacent to Mt. Wanda. West Hills Farm, a 44-acre land parcel supports additional chaparral scrub habitat and is also designated Critical Habitat for ALWH, so new sites will continue to be established in this area. Continued monitoring and data collection allow the park to better protect the species through informed management decisions and mitigation measures.

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Broad management objectives include those that support recreational, interpretive, and cultural use of the site, as well as maintaining natural resource protection, including supporting or enhancing the habitat as a suitable area for ALWH, and its diverse prey base. Additional park objectives include monitoring the current population of ALWH and its prey base (i.e., conducting trapping studies) and investigating the extent to which this species moves among and between habitat, through a long-term mark and recapture study. The information gathered during these studies can support the creation of appropriate long-term management objectives as it will provide a broad-scale, general understanding of the species on site and can give us some indication of the habitat requirement and characteristics that support this species.

ITERATURE CITED

Figure 1. Alameda whipsnake survey locations for spring and fall 2020 monitoring on Mt. Wanda.

Figure 3. Alameda whipsnake traplines for Fall 2021 monitoring on Mt. Wanda and West Hills Farm.

Table 1. 2021 ALWH capture data.

Date Trap Site Sex Age class Mark/Recapture Weight (grams) Total Length (mm)

4/27/2021 1A M Adult R15 112 1066.8 4/29/2021 10B M Adult R16 150 1212.85 5/13/2021 11B M Sub-adult R17 70 749.3 6/2/2021 2B M Adult R20 136 1010.92

6/25/2021 1B M Adult R18 137 1104.9 10/8/2021 8A F Juvenile R19 14.5 476.3

Table 2. Total number of ALWH captured between 2018 – 2021.

Age Class Sex Trap Site

Captured Adult Sub-Adult Juvenile Male Female

1A 2 1 0 1 2 0 1B 1 1 0 0 1 0 2B 1 1 0 0 1 0 4A 2 1 1 0 2 0 4B 5 3 1 1 1 4 5A 0 0 0 0 0 0 5B 2 2 0 0 1 1 6A 7 3 4 0 7 0 6B 5 4 0 1 4 1 8A 1 0 0 1 0 1 9A 4 3 0 1 4 0 9B 2 1 1 0 2 0

10A 1 1 0 0 1 0 10B 5 3 1 1 4 1 11B 1 0 1 0 1 0

Total 39 244 9 6 31 8

2018 2019 2020 2021

Total 22 4 7 6

Table 3. Environmental variables from 2021 monitoring season, presented as ranges from the start and end of the spring and fall season.

Temperature (°C) Humidity (%) Dew Point (°C) Season High Low High Low High Low Spring April 30 9 92 66 8 6 July 34 12 84 77 13 11 Fall October 32 11 83 44 11 9

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