Location: MSHCP > VOLUME 2 > AMBHIBIANS
arroyo toad (Bufo californicus)
State: Species of Special Concern
Federal: Endangered
The arroyo toad has narrow habitat requirements and limited distribution within the Plan Area, typically being restricted to the middle reaches of third order streams. Currently, the known distribution of arroyo toads within the Plan Area include Temecula Creek, Arroyo Seco Creek, Tenaja Creek, Los Alamos Creek, San Jacinto River, Bautista Creek, and Wilson Creek. These areas have also been modeled as key populations and habitat for this species. Primary habitat for this species includes suitable riparian habitat as described below, with secondary habitats including adjacent upland areas. Because the arroyo toad requires very specific breeding habitat conditions, only occurs within a few locations, and uses a well-defined habitat that is narrowly distributed, this species will require site specific considerations, protection of primary breeding habitat and adjacent upland areas, and species-specific conservation measures.
This is a species on the Additional Survey Needs and Procedures (Section 6.3.2) list and surveys for arroyo toad will be conducted as part of the project review process for public and private projects within the amphibian species survey area where suitable habitat is present (see Amphibian Species Survey Area Map, Figure 6-3 of the MSHCP, Volume I). Arroyo toad located as a result of survey efforts shall be conserved in accordance with procedures described within Section 6.3.2, MSHCP, Volume I. Other species survey requirements associated with the MSHCP are documented in Sections 6.1.2 and 6.1.3. A complete summary of all MSHCP species survey requirements is provided in Appendix E of Volume I.
The species-specific conservation objectives developed for this species are based upon the best available scientific information at the time of MSHCP preparation. Pursuant to Section 5.0 which includes Management, Monitoring and the Adaptive Management Program, the MSHCP's mitigation requirements will be monitored and analyzed to determine if they are producing the desired result. Based upon this information, the following species-specific conservation objectives will be adjusted if appropriate, as new information is gathered during Plan implementation. The Adaptive Management Program will be used to identify alternative strategies for meeting the MSHCP's general biological goals and objectives and, if necessary, adjusting future conservation strategies according to the information received.
Include within the MSHCP Conservation Area at least 1,602 acres of suitable breeding habitat (riparian scrub, woodlands and forests, meadows and marshes, and alluvial fan scrub habitat). Suitable breeding habitat for the arroyo toad includes low-gradient (usually less than 2 percent), sandy stream reaches that often (although not necessarily annually) support shallow pools with little current that persist for at least three months during the spring and summer.
Include within the MSHCP Conservation Area at least nine Core Areas which include portions of San Juan Creek (1,414 acres), Los Alamos Creek (7,898 acres), San Jacinto River (3,096 acres), Indian Creek (5,973 acres), Bautista Creek (3,148 acres), Wilson Creek (2,631 acres), Temecula Creek (5,663 acres), Arroyo Seco (2,798 acres), and Vail Lake (1,017 acres)(as discussed below).
Include within the MSHCP Conservation Area at least 7,005 acres of necessary suitable upland habitat as defined within the species account, adjacent to San Juan Creek, San Jacinto River, Indian Creek, Bautista Creek, Wilson Creek, Temecula Creek, Arroyo Seco, and Vail Lake, including agricultural lands, woodlands and forests, chaparral, coastal sage scrub, and grasslands.
Surveys for arroyo toad will be conducted as part of the project review process for public and private projects within the amphibian species survey area where suitable habitat is present (see Amphibian Species Survey Area Map, Figure 6-3 of the MSHCP, Volume I). Arroyo toad locations identified as a result of survey efforts shall be conserved in accordance with the procedures described in Section 6.3.2 of the MSHCP, Volume I.
Within the MSHCP Conservation Area, Reserve Managers shall maintain or, if feasible, restore ecological processes within occupied habitat and suitable new areas within the Criteria Area, given existing constraints and activities covered under the MSHCP. At a minimum, these areas will include portions of San Juan Creek, San Jacinto River, Indian Creek, Bautista Creek, Wilson Creek, Temecula Creek, Arroyo Seco, and Vail Lake, which are important to the arroyo toad.
NOTE: Maintaining or, if feasible, restoring ecological processes within the MSHCP Conservation Area may include: allowing for natural dynamic fluvial processes of flooding and habitat regeneration, and possibly fire, to maintain healthy alluvial fan habitat, and other riparian habitat; careful planning and design of existing and future authorized used that may affect natural processes such as flood control, water conservation, and sand and gravel mining; controlling or removing known threats from important arroyo toad creeks and rivers (i.e., portions of San Juan Creek, San Jacinto River, Indian Creek, Bautista Creek, Wilson Creek, Temecula Creek, Arroyo Seco, and Vail Lake), including, but not limited to, eliminating non-native fishes and bullfrogs; restoring natural hydrologic processes; limiting livestock access to streams, creeks, ponds, and pools; limiting recreational use of certain areas; altering water use; controlling farming and agricultural practices within and adjacent to occupied habitat or upstream of occupied habitat; controlling weed abatement, discing, and pesticide/herbicide use adjacent and upstream of occupied habitat, and; removing exotic vegetation.
Within the MSHCP Conservation Area, maintain breeding populations at a minimum of 80 percent of the conserved breeding locations as measured by the presence/absence of juveniles toads (roughly 10 to 30 mm [Sweet 1993]), tadpoles, or egg masses across any 5 consecutive years.
For purposes of this conservation analysis, potential habitat for the arroyo toad includes shallow, slow-moving medium to large streams with a low gradient and adjacent open riparian habitat. These areas have not been specifically mapped for the MSCHP Plan Area, however, the USFWS (2001) has modeled areas within western Riverside County which meet the habitat criteria of the arroyo toad and also are known to support them. Therefore, species coverage is based on population preservation and suitable occupied habitat preservation.
The Plan Area supports approximately 11,224 acres of modeled suitable habitat. As stated below under Data Characterization, known suitable breeding habitat in western Riverside County includes portions of upper San Juan Creek, San Jacinto River, Los Alamos Creek, Indian Creek, Bautista Creek, Wilson Creek, Temecula Creek, Arroyo Seco, and Vail Lake. Suitable habitat also covers adjacent uplands (alluvial terraces and valley bottom lands) up to 25 m above stream channels or 1.5 km away from the stream channel, whichever is less. These limits attempt to exclude developed areas. As shown in Table 1, conservation of potential breeding habitat include riparian scrub, woodlands, and forests; meadows and marshes, and; alluvial fan scrubs for the arroyo toad. Approximately 1,602 acres (84 percent) of the suitable breeding habitat in the Plan Area would be conserved in the MSHCP Conservation Area. As shown in Table 2, adjacent upland includes chaparral; coastal sage scrub; agricultural lands; woodlands and forests; and grasslands, within those narrow parameters. Approximately 7,005 acres (75 percent) of the suitable breeding habitat in the Plan Area would be conserved in the MSHCP Conservation Area. Overall, approximately 8,607 acres total (77 percent) will be conserved in the MSHCP Conservation Area. These lands will be managed for wildlife resources including the arroyo toad.
As described above under Data Characterization, there are only six MSHCP data points and other occurrences which can be used for population preservation determination. These data points and locations are thought to define the general population distribution within western Riverside County.
Three key occupied suitable habitat areas as modeled by the USFWS (2001) are mostly conserved under the Plan. The San Juan area is part of a larger unit which reaches well into Orange County, The San Jacinto watershed area is important because it is at the eastern limits of the species range and is located in higher elevation areas, and the Santa Margarita watershed area protects an important
TABLE 1
SUMMARY OF BREEDING HABITAT CONSERVATION
FOR THE ARROYO TOAD1
| Within MSHCP Conservation Area | Outside MSHCP Conservation Area | ||||||
|---|---|---|---|---|---|---|---|
| Vegetation Type | Plan Area (Acres) | Criteria Area2 (Acres) | Public/ Quasi-Public (Acres) | Total Within MSHCP Conservation Area (Acres) | Rural/ Mountainous (Acres) | Outside MSHCP Conservation Area (Acres) | Total Outside MSHCP Conservation Area (Acres) |
| Meadow and Marshes | 85 | 84 | 0 | 84 | 0 | 1 | 1 |
| Riparian Scrub, Woodland and Forest | 1,036 | 790 | 45 | 835 | 2 | 199 | 201 |
| Riversidean Alluvial Fan Sage Scrub | 777 | 683 | 0 | 683 | 0 | 94 | 94 |
| TOTAL | 1,898 | 1,557 | 45 | 1,602 | 2 | 294 | 296 |
| 1 Includes occupied portions of Los Alamos Creek, San Juan Creek, San Jacinto River, Indian Creek, Bautista Creek, Wilson Creek, Temecula Creek, Arroyo Seco, and Vail Lake plus adjacent uplands. 2 Acres refer to Additional Reserve Lands to be assembled from within the Criteria Area. |
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TABLE 2
SUMMARY OF UPLAND HABITAT CONSERVATION
FOR THE ARROYO TOAD
| Within MSHCP Conservation Area | Outside MSHCP Conservation Area | ||||||
|---|---|---|---|---|---|---|---|
| Vegetation Type | Plan Area1 (Acres) | Criteria Area2 (Acres) | Public/ Quasi-Public (Acres) | Total Within MSHCP Conservation Area (Acres) | Rural/ Mountainous (Acres) | Outside MSHCP Conservation Area (Acres) | Total Outside MSHCP Conservation Area (Acres) |
| Agricultural Land | 1,463 | 577 | 8 | 585 | 14 | 864 | 878 |
| Chaparral | 4,816 | 1,611 | 2,207 | 3,818 | 190 | 808 | 998 |
| Coastal Sage Scrub | 1,792 | 1,601 | 44 | 1,645 | 14 | 133 | 147 |
| Grassland | 1,003 | 632 | 82 | 714 | 1 | 288 | 289 |
| Woodlands and Forest | 252 | 148 | 95 | 243 | 0 | 9 | 9 |
| TOTAL | 9,326 | 4,569 | 2,436 | 7,005 | 23,336 | 2,102 | 2,321 |
| 1 Includes occupied portions of Los Alamos Creek, San Juan Creek, San Jacinto River, Indian Creek, Bautista Creek, Wilson Creek, Temecula Creek, Arroyo Seco, and Vail Lake plus adjacent uplands. 2 Acres refer to Additional Reserve Lands to be assembled from within the Criteria Area. |
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population and upper reaches of one of the most natural watersheds remaining in coastal southern California. These area are not connected to one another, but other conserved creeks and watersheds with potentially suitable habitat are connected to the areas. Some of these creeks once supported arroyo toad and may again with proper management. Forest Service lands play an important part in preserving existing populations and suitable habitat. Portions of all three areas occur in Forest Service lands: portions of the San Juan area occurs within general forest lands in the Santa Ana Mountains and the San Mateo Canyon Wilderness; portions of the Santa Margarita watershed area occurs within the Agua Tibia Wilderness and general forest lands within the Palomar Mountains, and; portions of the San Jacinto area occurs within general forest lands within the San Jacinto Mountains. Additionally, the Cleveland National Forest protects much of the Los Alamos Creek watershed both within general forest and the San Mateo Canyon Wilderness.
Modeled arroyo toad habitat is distributed throughout the MSHCP Conservation Area where described. These areas occur within the following Core Areas: Vail Lake (portion of Proposed Core 7; 1,017 acres), San Juan Creek(portion of Existing Core B; 1,414 acres), Los Alamos Creek (portion of Existing Core B; 7,898 acres), San Jacinto River (portions of Proposed Core 5 and Existing Core K; 3,096 acres), Indian Creek (portion of Existing Core K; 5,973 acres), Bautista Creek (portions of Proposed Core 4, Constrained Linkage D, and Existing Core K; 3,148 acres), Wilson Creek (portion of Proposed Core 7; 2,631 acres), Temecula Creek (portion of Proposed Core 7; 5,663 acres), and Arroyo Seco Creek (portion of Existing Core M; 2,798 acres). All of these contain, or are expected to contain, the habitat requirements necessary to support arroyo toad populations. In addition, linkages between the blocks of habitat will be conserved.
Implementation of the MSHCP, including the conservation of the existing populations and suitable habitat as described above, will maintain viable populations of the arroyo toad and facilitate recovery of the species. The current distribution is thought to be known, however some areas which may support the toad are relatively inaccessible and are visited sporadically at best. Population numbers are known to fluctuate from year to year, based on natural and un-natural circumstances. However, surveying for existing and new populations is relatively easy if access is available. Ensuring that the species remains viable in the MSHCP Plan Area will require implementing the proposed systematic monitoring program.
In summary, conservation for the arroyo toad will be achieved by the inclusion of at least 8,607 acres of suitable Conserved breeding and adjacent upland Habitat within nine Core Areas which are composed of streams or rivers with adjacent uplands within the MSHCP Conservation Area. The Core Areas are not necessarily connected to one another, but potential linkages exist. In addition, surveys for arroyo toad will be conducted as part of the project review process for public and private projects within the amphibian species survey area where suitable habitat is present (see Amphibian Species Survey Area Map, Figure 6-3 of the MSHCP, Volume I). Arroyo toad locations identified as a result of survey efforts will be conserved in accordance with the procedures described in Section 6.3.2 of the MSHCP, Volume I. Other species survey requirements associated with the MSHCP are documented in Sections 6.1.2 and 6.1.3. A complete summary of all MSHCP species survey requirements is provided in Appendix E of Volume I. Within the MSHCP Conservation Area, Reserve Managers will maintain or, if feasible, restore ecological processes within occupied habitat and suitable new areas, given existing constraints and activities covered under the MSHCP. At a minimum, these areas will include portions of San Juan Creek, San Jacinto River, Indian Creek, Bautista Creek, Wilson Creek, Temecula Creek, Arroyo Seco, and Vail Lake, which are important to the arroyo toad. Within the MSHCP Conservation Area, Reserve Managers will maintain breeding populations at a minimum of 80 percent of the conserved breeding locations as measured by the presence/absence of juveniles toads, tadpoles, or egg masses across any five consecutive years. Furthermore, the Plan Area is contiguous with suitable habitat in eastern Riverside, San Bernardino, Orange, and San Diego counties.
Approximately 296 acres (16 percent) of occupied and modeled suitable breeding habitat and 2,321 (25 percent) of occupied and modeled suitable upland habitat adjacent to breeding habitat (2,617 acres total [23 percent]), would be located outside the MSHCP Conservation Area, and individuals within these areas will be subject to Incidental Take consistent with the Plan. Outlying areas will be subject to surveys and protection. Because the location of these occupied areas is yet unknown, the following gaps are identified. Gaps in modeled suitable habitat coverage occur within the San Jacinto and Santa Margarita Watershed areas. Gaps within the San Jacinto area primarily occur on Forest Service and Bureau of Land Management in-holdings along Bautista Creek (Sections 27, 26, 34, and 35 [T.5S., R.1W.] and Section 1 [T.6S., R.1E.]) and on forest in-holdings (Sections 17, 18, 19, ad 20 [T.5S., R.2E.] and Section 13 [T.5S., R.1.E.]) and other areas (Sections 10, 11, 14, and 15 [T.5S., R.1E.]) along the San Jacinto River. Gaps within the Santa Margarita Watershed area primarily occur on forest service in-holdings along Arroyo Seco Creek in the vicinity of Crosley Homestead (Sections 25 and 36 [T.8S., R.1W.], Sections 1 and 2 [T.9S., R1W.], and Section 31 [T.8S., R.1E.]) and other areas along Temecula Creek in the Aguanga Valley (Sections 19, 28, 29, 33, and 34 [T.8S., R.1E.]) although the main creek areas are included with minimum 1,000-foot buffers.
A variable amount of information exists for the arroyo toad, though most of the studies focus on the northern population and breeding ecology. Little information is available on the year-round activities of both sexes and definitive movement characteristics. The arroyo toad was listed as endangered in December 1994 (U.S. Fish and Wildlife Service 1994) and Critical Habitat was designated in February 2001 (U.S. Fish and Wildlife Service 2001; *NOTE: Critical Habitat is currently under legal review). A Recovery Plan has been prepared by the U.S. Fish and Wildlife Service (1999) which outlines the status and life history of the toad, recovery goals and tasks, and an implementation schedule. The MSHCP database holds 25 records for Bufo californicus. Of the 25 records, 3 (12 percent) are precision code "1" (an "x" and "y" coordinate that allows for good precision in the location), 3 (12 percent) are precision code "2" (one "x" or "y" dat point or equivalent), and 18 (72 percent) are precision code "3" or "4" (relatively imprecise locations from general areas). One of the Precision code "1" records is from 1998, another is from 1987, the last is undated. Of the precision code "2" records, one is from 1990 and two are undated. One 1997 precision code "3" record is from the Vail Lake area, well within the proposed reserve, and is considered recent and useful for analysis purposes. The undated precision code "1" location near the southern intersection of State Route 79 and Arroyo Seco is considered valid for analysis purposes because it is also located within federal documents (USFWS 2001). Additional locations not included in the MSHCP data base, but cited by the U.S. Fish and Wildlife Service (2001) include locations in the San Jacinto River and Bautista Creek (both within the San Bernardino National Forest and modeled suitable habitat). All told, there are 6 locations which may be considered for analysis. However, the U.S. Fish and Wildlife Service has reviewed all known locations and distribution, reviewed suitable habitat, and modeled suitable habitat. Thus, their analysis of all information is comprehensive enough to guide reserve design within the Plan Area.
Arroyo toads are found in foothill canyons and inter-mountain valleys where the river is bordered by low hills and the stream gradient is low (Miller and Miller 1936, Sweet 1992). The arroyo toad is an extreme habitat specialist, restricted to riparian environments in the middle reaches of third order streams (Sweet 1989). Arroyo toads are known to either breed, forage, and/or aestivate in aquatic habitats, riparian, coastal sage scrub, oak, and chaparral habitats. Holland (2001) found that on Camp Pendleton, California, large numbers of arroyo toads even utilized non-native exotic Arundo donax patches within otherwise suitable habitat. The species is currently thought to be restricted to the headwaters of large streams with persistent water from March to mid-June that have shallow, gravely pools less than 18 inches deep, and adjacent sandy terraces. Upland burrows have been noted for this species. Patterns of habitat use by sub-adults and non-breeding adults is not well understood (Sweet 1992).
Breeding pools must be open and shallow with minimal current, and with a sand or pea gravel substrate overlain with sand or flocculent silt (Sweet 1989). Adjacent banks must provide open, sandy or gravely terraces with very little herbaceous cover for adult and juvenile foraging areas, within a moderate riparian canopy of cottonwood, willow, or oak. Heavily shaded pools are unsuitable for larvae and juvenile toads due to lower water and soil temperatures and poor algal mat development (Sweet 1992). Episodic flooding is critical to keep the low terraces relatively vegetation free. Juveniles favor areas which remain damp and contain less than 10 percent cover, as these sites possess the thermal and refuge characteristics required for juvenile survival and rapid growth (Sweet 1992). Larval growth appears to be more rapid in pools with low silt loads (Jennings and Hayes 1994). Adults use terraces in the 100-year flood zone, which may extend up to 100 m from the stream (Campbell et.al. 1996), however, more recent data suggest that they may move between 1 and 2 km into adjacent upland habitats to estivate. Most terraces are not immediately adjacent to the stream, but are separated by a dynamic, channel margin zone of mixed sediments which is reworked as storm waters flood the primary channel (Campbell et.al. 1996). Drainages with straighter courses will have broader marginal zones and fewer terraces but may have associated oak flats that provide suitable adult habitat (Campbell et.al. 1996). Adults excavate shallow burrows on the terraces where they shelter during the day when the surface is damp or during longer intervals in the dry season.
Coastal plain and mountain streams of Southern California west of the desert from San Antonio River (Ft. Hunter-Liggett), in Monterey County (USFWS 1994), and near Santa Margarita, San Luis Obispo County, to northwestern Baja California, Mexico. However, there are known populations along the desert slope including the Mojave River, San Bernardino County, and Little Rock Creek, Whitewater River, San Felipe Creek, Vallecito Creek, and Pinto Canyon Riverside County, California (Jennings and Hayes 1994, Patton and Myers 1992, Stebbins 1985).
There are scattered historic occurrences near the area southwest of Lake Elsinore in Temescal Wash, and south of Vail Lake, the Whitewater River north of I-10, and Santa Margarita River Basin below 609 meters elevation. Recent surveys have located populations of arroyo toads in Temecula, San Mateo, and Tenaja creeks (Campbell et.al. 1996). One population occurs at Dripping Springs along Arroyo Seco near Vail Lake. Other recent localities include San Jacinto River, Bautista Creek, and Wilson Creek.
Key population areas based on currently known populations include Bautista Creek, Wilson Creek, Los Alamos Creek, Temecula Creek, Arroyo Seco, Tenaja Creek, San Jacinto River, and Vail Lake environs. In addition, the USFWS has a number of watersheds included in the Southern Recovery Unit for this species within Western Riverside County. These include Recovery Unit 9, 11 km of the San Jacinto River from the Sand Canyon confluence to just below the Indian Creek confluence, the lower 1 km of Indian Creek, and 11 km of Bautista Creek from the middle of Section 20 (T6S, R2E) to the middle of section 27 (T5S. R1E); Recovery Unit 10, upper San Juan Creek from Decker Canyon to the Orange County boundary, and; Recovery Unit 13, 25 km of Temecula Creek from Dodge Valley to Vail Lake, 6 km of Wilson Creek from Lancaster Valley to Vail Lake, and 11 km of Arroyo Seco Creek from Crosley Homestead to Vail Lake.
Genetics: Originally described by Camp (1915) as a subspecies of the Great Plains toad (Bufo cognatus), the arroyo toad was subsequently given its own species designation as Bufo californicus by Myers (1930) Pickwell (1947) Wright and Wright (1949), then a subspecies of Bufo compactilis by Linsdale (1940) and Bufo woodhousii (Shannon 1949). The arroyo toad was then considered to be a subspecies of Bufo microscaphus (Stebbins 1951, 1966, 1985). This toad has been treated as a subspecies of Bufo microscaphus since, however it is becoming increasingly clear that it is morphologically differentiated from the other two subspecies B. m. microscaphus and B. m. mexicanus (Jennings and Hayes 1994). Gergus (1998) compared allozyme frequencies between the three subspecies and found that the discrete differences support the hypothesis that they exhibit mutually exclusive evolutionary lineages and each should be recognized as a separate species. The current recommendation reverts to Myers' 1930 conclusion that the arroyo toad is Bufo californicus.
Diet and Foraging: Larvae feed by inserting their head into the substrate and injecting loose organic material such as interstitial algae, bacteria, and diatoms. They do not forage on macroscopic vegetation (Sweet 1992, Jennings and Hayes 1994, USFWS 1999). Post-metamorphose (juvenile) toads rely on ants (USFWS 1999) almost exclusively. By the time they reach 17 to 23 mm in length, they take more beetles along with the ants (Sweet 1992, USFWS 1999). Adult toads probably consume a wide variety of insects and arthropods including ants, beetles, spiders, larvae, caterpillars, and others. Holland (2001) found that arroyo toad may forage on non-native Argentine ants.
Daily Activity: Cunningham (1962) found that post-metamorphic toads are diurnal for the first four to five weeks. After they reach the 17-23 mm range they switch to a nocturnal activity pattern and utilize sandy burrows or adjacent debris during the day. Larger juveniles and adults spend more time away from the waters edge, but remain primarily nocturnal (Cunningham 1962; Sweet 1992). During the breeding season, advertisement activity begins approximately one hour after sunset and may continue beyond sunrise (USFWS 1999). However, activity is thought to decline during full moon phases.
Reproduction: Sweet (1992) studied a population of arroyo toads in the northern part of their range and found that initiation of breeding activity is usually associated with rainfall and temperatures above 45 degrees Fahrenheit. In western Riverside County, breeding activity usually starts in late February or early March but may occur as early as January (USFWS 1999). Males call from the edge of pools (USFWS 1999; Sweet 1992) where females find them and once in amplexus, the eggs are laid (Sweet 1992). The female releases her entire clutch of 2,000 to 10,000 eggs at a single site and are probably unable to produce a second clutch (Sweet 1992). Sweet's 1992 and 1993 study (1993) found that calling (breeding attempts) by yearling males, stunted their growth when compared to non-calling (breeding) cohorts. Sweet found that some of the larger yearling males attempted to breed while the smaller cohorts did not but grew larger so that by the next breeding season, the abstinent class was larger. Females are more attracted to larger males with deeper calls (Sullivan 1992); therefore, it may be better to wait a season before breeding.
This species requires access to permanent water during the breeding season and unrestricted corridors for movement from water sources to adjacent upland stream terrace habitat where much of the remaining active season is spent. These toads have "perhaps the most specialized habitat requirements of any amphibian in California" (Jennings and Hayes 1994). Breeding pools appear to meet specific requirements only in the middle reaches of second (or occasionally third) order streams. The species exhibits an explosive breeding period, generally forming linear, loosely organized choruses along streams (Sullivan 1992).
Survival: Because of the arroyo toads natural history, size, and reclusiveness, survival rates are inherently difficult to track. However, some data exists which are derived from largely single-year studies. Sweet (1989, 1993) found that at the end of a 4-year drought (1990), only 27 toads released egg clutches, whereas in following years (1991 and 1992) during above-average rainfall they released 166 and 263 clutches. Sweet (1993) also made the general statements that streamflow alteration by humans can cause the loss of an entire cohort, and larvae survivorship is high in ponds without fish but low in ponds with fish.
In general, toads and frogs rate of mortality decreases as size increases (Werner 1986). Sweet (1992) found that arroyo toad mortality rates were consistent with this pattern. Sweet found that the per day mortality rate for juvenile arroyo toads 12-16 mm in length was 7.6 percent while the rate for toads 24-28 mm was 3.3 percent per day. Sweet (1993) estimated that the minimal overwinter survival rate for males is 64 percent, sub-adult males is 55.5 percent, females is 33 percent, and sub-adult females is 32 percent based on a single-year study at Los Padres National Forest.
Dispersal: Sweet (1993) found that many sub-adults and some males moved along streams >0.8 km in distance and 1.0 km in some cases. More recent studies have found linear movement along drainages to range between 1 and 2 kilometers. While Campbell et al. (1996) theorized that the exchange of individuals over ridgelines and into adjoining drainages is unlikely due to the females sedentary habits and extent of topographic relief between typical third to fifth order streams. Holland (USFWS 1999) found that arroyo toads are capable of moving 0.5 to 2.0 km into adjacent habitats and may not be constrained by topography. Sweet's study in the Los Padres National Forest (1993), generally concluded that most arroyo toads disperse from their natal pools about a year after metamorphosis. The females become more sedentary as they mature, while many, but not all males maintain a tendency to move up or down the drainage during the breeding season. Sweet (1993) also found a lack of movement between August and late March. Finally, it is hypothesized that some accidental dispersal downstream is caused by flood or large storm events.
Socio-Spatial Behavior: Larvae will likely occur at the margins of a pool during the day but will move to interior portions of the pool during the nighttime (Sweet 1993, Campbell 1996). After metamorphosis, juveniles are too small to dig burrows and must remain moist, therefore they station themselves near the natal pool on moist sand and find shelter in depressions, holes, or under leaves, rocks or debris. Once they reach 23 mm in size, they can dig burrows in loose sandy ridges adjacent to the natal area which are probably shaded, returning to the moist sand bars during the nighttime to feed (Sweet 1992). After reaching 28 to 30 mm in size, arroyo toads shift to the distant margins of the sand terraces and into adjacent willow scrub habitat. During the winter, toads burrow 5 to 10 cm deep in dry sand or at the dry/damp sand interface at the canopy edge of riparian or chaparral vegetation (Sweet 1992).
Sweet's (1993) study in Mono Creek found that during a poor year the population density was 4 to 4.5 toads per hectare, while during a good rainfall year the density was 11.6 to 12.8 toads per hectare. Males exhibit a strong site fidelity during the breeding season (Sweet 1991) which may indicate some territoriality. However, aggression between males has not been noted.
Community Relationships: Little is known of the community ecology of the arroyo toad. What is known comes largely from Sweet (1992) and is based on interactions with western toad (Bufo boreas). The arroyo toad and western toad both utilize similar habitats and often breed in similar pools, therefore the potential for interactions is great. Larval forms of the species probably do not compete for food resources due to the arroyo toads unique foraging strategy. Juveniles, however, probably compete for the same food resources along sand bars. Extensive overlap in habitat use and high densities (Sweet 1992), combined with differing foraging strategies probably has a fitness cost to one or both of the species. Sweet (1992) found that in the lab, arroyo toads were smaller when raised with western toads, than when reared alone. Some male arroyo toad may breed with small western toad, but the eggs are infertile.
The arroyo toad has been extirpated from 75 percent of its former range (USFWS 1994), however since the listing of the arroyo toad, numerous new locations have been located through site specific surveys. Although a substantial proportion of currently occupied habitat is found on National Forest lands, recovery of arroyo toads on privately owned lands will be necessary to recovery of the species. Toad habitat requirements and habitat loss may act in concert to functionally isolate populations (Campbell et.al. 1996). The remaining 25 percent of occupied habitat are threatened by dam construction, river diversion, conversion of riparian wetland habitat by agriculture and urbanization, road construction, off-highway vehicle use, campground development, grazing, and mining activities. Additionally, care must be taken when initiating riparian habitat restoration, (including weed removal) as evidenced by Holland's (2001) discovery that they can use Arundo donax patches extensively.
Artificial flow augmentation and withdrawal from dam releases in February though August encourages vegetative growth in riparian corridors, and disrupts the natural fluvial processes that produce the terrace pool habitats required by arroyo toads (Sweet 1992). Currents of 5 cm/sec or greater are sufficient to displace eggs and embryos/larvae up to 82 hours post hatching (Sweet 1992). Sedimentation sources will negatively impact arroyo toad habitat, and therefore, should be monitored and controlled (Sweet 1999, pers. com.). In addition, populations which are unable to migrate across altered or otherwise inhospitable terrain between disjunct population groups result in genetic isolation. Off-road vehicle use in stream beds and along banks cause significant impacts to arroyo southwestern toads. Stream diversions leads to early drying of breeding pools, and restriction of the foraging period essential for rapid growth, and loss of damp subsurface soil, which may result in high adult mortality (Sweet 1992). Introduced plants and predators can cause substantial reductions in the size of extant populations, and may have contributed to regional extinctions of arroyo toads (Hayes and Jennings 1986). Predatory fish, such as introduced mosquito fish and arroyo chub, that prey on tadpoles are found in virtually all occupied and once occupied streams (Sweet 1992), and introduced bullfrogs which prey on adult arroyo toads are encouraged by artificially maintained perennial streams (Sweet 1993). Additionally, as little as 5 to 6 Argentine ant stings may produce lethal effects (Holland 2001).
The extended 5-year drought in Southern California during the late 1980's, when combined with water diversions from streams created extremely stressful conditions for most aquatic species. The effect of drought and water diversion on arroyo toads is that female toads may find insufficient insect prey to acquire enough fat storage for egg production before males cease their courtship behavior of calling, resulting in no reproduction that year (Sweet 1992). The recent years of extremely low reproductive success has likely resulted in a reproductive bottleneck in the remaining populations of arroyo toads, in which few individuals reached sexual maturity from 1990 to 1995 (Sweet 1992). Sullivan (1992) found that there is a differentiation in the sound frequency between larger and smaller males. This may affect mate selection by females. Low reproductive rates or success affects the size and extent of the resulting cohorts. Missing or reduced cohorts combined with the possibility that females select for certain frequencies when selecting a mate, may further reduce the reproductive rate of the population.
Numerous local extinctions likely occurred during the 1990 to 1995 drought. In addition to drought, other deleterious factors are many: trampling of toads or crushing them within burrows on stream terraces by grazing animals and wild pigs and crushing of toads in open areas, such as campground roads and off-highway vehicle use areas, where they forage at night. Campground garbage also attracts artificially high populations of racoons which predate on arroyo toads (Sweet 1999, pers com). Finally, suction dredge mining often occurs in and adjacent to breeding pools, which are destroyed by dredging (Campbell et.al. 1996). Siltation in arroyo toad breeding pools can asphyxiate eggs and newly hatched larvae and make foraging impossible.
Specific threats by key population area include the following (Stephenson 2001, pers com):
Temecula and Wilson Creeks - Most of the arroyo toad habitat along these drainages are in private ownership and are particularly threatened by water diversions, groundwater overdraft, sand and gravel mining, tilling of agricultural fields on the stream terrace, and future urbanization.
Arroyo Seco Creek - The recent establishment of vineyards in the upper reach of this drainage on private inholdings within the Cleveland National Forest threatens arroyo toad habitat downstream. This is due to large water diversions associated with the crop. Pesticide runoff may also have a deliterious affect on downstream toads. High quality arroyo toad habitat is currently being impacted by a large Recreational Vehicle campground at the bottom of the drainage.
Bautista Creek - This population is currently threatened by a proposed project to pave the road from Hemet to Anza that runs along the creek. This will greatly increase traffic on the road, leading to increased toad road mortalities.
San Jacinto River - Most of the arroyo toad habitat is on private or Indian land and threatened by development. A reduction in water table levels is also a concern.
Los Alamos Creek - The portion of this drainage known to be occupied by arroyo toads lies along the western edge of the Santa Rosa Plateau in an area of increasing ranchette development.
Camp, C.L. 1915. Batrachoceps major and Bufo cognatus californicus, new amphibia from southern California. University of California Publications in Zoology 12 (12): 327-334.
Campbell, L.A., T.B. Graham, L.P. Thibault, and P.A. Stine. 1996. The arroyo toad (Bufo microscaphus californicus) ecology, threats, recovery actions, and research needs. U.S. Department of the Interior, National Biological Service, California Science Center, Davis, California, Technical Report (NBS/CSC-96-01). ii +46 pp.
Cunningham, J.D. 1962. Observations on the natural history of the California toad, Bufo californicus Camp. Herpetologica 17 (4): 255-260.
Fisher, R., and T. Case.1997. A field guide to the amphibians and reptiles of coastal southern California. Special Publ. Biol. Res. Division, United States Geol. Survey.
Gergus, E.W. 1998. Systematics of the Bufo microscaphus complex: allozyme evidence. Herpetologica 54 (3):317-325.
Hayes, M. P., and M. R. Jennings. 1986. Decline of ranid frog species in western north America: Are bullfrogs (Rana catesbeiana) responsible? Journal of Herpetology 20(4):490-509.
Holland, D.C. and R.H. Goodman. 1998. A guide to the Amphibians and reptiles of MCB Camp Pendleton, San Diego County, California. Report submitted to AC/S Environmental Security, Resource Management Division, MCB Camp Pendleton, Contract M00681-94-C-0039. Unpaginated.
Jennings, M. R., and M. P. Hayes. 1994. Amphibian and reptile Species of Special Concern in California. Final report submitted to California Department of Fish and Game, Inland Fisheries Division, Rancho Cordova, California, under Contract 8023. Pg. 54-58.
Linsdale, J.M. 1940. Amphibians and reptiles in Nevada. Proceedings of the American Academy of Arts and Sciences. 73 (8): 197-257.
Miller, L. and A.H. Miller. 1936. The northern occurrence of Bufo californicus in California. Copeia: 176.
Myers, G.S. 1930. The status of the southern California toad, Bufo californicus (Camp). Proceedings of the Biological Society of Washington. 43 (11): 73-78.
Patten, M.A., and S.J. Myers. 1992. Geographic distribution. Bufo microscaphus californicus. Herpetological Review 23 (4):124.
Pickwell, G. 1947. Amphibians and reptiles of the Pacific States. Stanford University Press, Stanford, Californica. xiv + 236 pp.
Shannon, F.A. 1949. A western subspecies of Bufo woodhousii hitherto erroneously associated with Bufo compactilis. Bulletin of the Chicago Academy of Sciences 8 (15): 301-312.
Stebbins, R. C. 1951. Amphibians of western North America. University of California Press, Berkeley and Los Angeles, California. ix + 539 pp.
_________. 1966. A field guide to western reptiles and amphibians. Houghton-Mifflin Company, Boston, Massachusetts. xiv +279 pp.
_________. 1985. A field guide to western reptiles and amphibians. McGraw Hill Book Company, New York, New York.
Sullivan, B. K. 1992. Calling behavior of the southwestern toad (Bufo microscaphus). Herpetologica 48:383-389.
Sweet, S. S. 1989. Observations on the biology and status of the arroyo toad, Bufo microscaphus californicus, with a proposal for additional research. Department of Biological Sciences, University of California, Santa Barbara, California. Unpublished report. 23 pp.
Sweet, S. S. 1992. Ecology and status of the arroyo toad (Bufo microscaphus californicus) on the Los Padres National Forest of southern California, with management recommendations. Contract report to United States Department of Agriculture, Forest Service, Los Padres National Forest, Goleta, California. 198 pp.
Sweet, S. S. 1993. Second report on the biology of the arroyo toad (Bufo microscaphus californicus) on the Los Padres National Forest of southern California. Contract report to United States Department of Agriculture, Forest Service, Los Padres National Forest, Goleta, California. 73 pp.
U.S. Fish and Wildlife Service. 1994. Endangered and threatened wildlife and plants; determination of endangered status for the arroyo southwestern toad. Federal Register 59 (241): 64859-64866.
____________. 1999. Arroyo southwestern toad (Bufo microscaphus californicus) recovery plan. U.S. Fish and Wildlife Service, Portland, Oregon. Vi + 119pp.
____________. 2001. Endangered and threatened wildlife and plants; final designation of critical habitat for the arroyo toad; final rule. Federal Register 66 (26): 9414 -9474.
____________. 2001. Endangered and threatened wildlife and plants; final designation of critical habitat for the arroyo toad; Correction. Federal Register 66 (45): 13656-13571.
Zeiner, D. C., W. Laudenslayer, and K. Mayer. 1988. California's wildlife, Volume I: Amphibians and reptiles. California Department of Fish and Game, Sacramento, California. 272 pp.
California red-legged frog (Rana aurora draytonii)
State: Species of Special Concern, California Protected Species
Federal: Threatened
The California red-legged frog has narrow habitat requirements and limited distribution within the Plan Area, typically being restricted to the lowland streams, wetlands, and pools where dense vegetation surrounds relatively deep water with small (<300 km2) watersheds. They also require adjacent upland areas to move between suitable breeding sites. Currently, the known distribution of red-legged frogs within the Plan Area is limited to the Santa Rosa Plateau (Cole Creek). Suitable plateau and drainage habitat and connections to other suitable habitat in the southern Santa Ana Mountains has been delineated for this species. Primary breeding habitat for this species includes suitable wetland habitat as described below, with secondary habitats including adjacent upland areas. Because the red-legged frog requires very specific breeding habitat conditions, only occurs within a single location, and uses a well defined habitat that is narrowly distributed, this species will require site specific considerations, protection of primary breeding habitat and adjacent upland areas, and species-specific conservation measures.
This is a species on the Additional Survey Needs and Procedures (Section 6.3.2) list and surveys for California red-legged frog will be conducted as part of the project review process for public and private projects within the amphibian species survey area where suitable habitat is present (see Amphibian Species Survey Area Map, Figure 6-3 of the MSHCP, Volume I). California red-legged frogs located as a result of survey efforts shall be conserved in accordance with procedures described within Section 6.3.2, MSHCP, Volume 1. Other species survey requirements associated with the MSHCP are documented in Sections 6.1.2 and 6.1.3. A complete summary of all MSHCP species survey requirements is provided in Appendix E of Volume I.
The species-specific conservation objectives developed for this species are based upon the best available scientific information at the time of MSHCP preparation. Pursuant to Section 5.0 which includes Management, Monitoring and the Adaptive Management Program, the MSHCP's mitigation requirements will be monitored and analyzed to determine if they are producing the desired result. Based upon this information, the following species-specific conservation objectives will be adjusted if appropriate, as new information is gathered during Plan implementation. The Adaptive Management Program will be used to identify alternative strategies for meeting the MSHCP's general biological goals and objectives and, if necessary, adjusting future conservation strategies according to the information received.
Include within the MSHCP Conservation Area at least 766 acres of occupied and historic breeding habitat (riparian scrub, woodlands and forests, open water, and playas and vernal pools). Breeding habitat for the red-legged frog includes cool, deep pools, lowland streams, and other wetlands where dense vegetation surrounds relatively them. These areas generally have a small (<300 km2) watershed.
Include within the MSHCP Conservation Area the Core Areas in the Santa Rosa Plateau (9,028 acres) and the southern Santa Ana Mountains (30,964 acres), and the intervening lands which shall provide movement between the Core Areas. The intervening lands are primarily situated around Avenoloca Mesa, Redonda Mesa, slopes and foothills of Squaw Mountain, and Alamos Canyon.
Include within the MSHCP Conservation Area at least 39,147 acres of upland habitat adjacent to occupied or suitable breeding habitat. These areas are situated around the Santa Rosa Plateau, southern Santa Ana Mountains, and intervening lands including Avenoloca Mesa, Redonda Mesa, slopes and foothills of Squaw Mountain, Alamos Canyon and environs. Upland habitats include woodlands and forests, chaparral, coastal sage scrub, and grasslands.
Surveys for this species will be conducted as part of the project review process for public and private projects within the amphibian species survey area where suitable habitat is present (see Amphibian Species Survey Area Map, Figure 6-3 of the MSHCP, Volume I). Red-legged frog locations identified as a result of survey efforts shall be conserved in accordance with procedures described within Section 6.3.2, MSHCP, Volume I.
Within the MSHCP Conservation Area, Reserve Managers shall maintain or, if feasible, restore ecological processes within occupied habitat and suitable new areas within the Criteria Area. At a minimum, these areas will include the Santa Rosa Plateau, San Mateo Wilderness area of the Cleveland National Forest, Squaw Mountain, Avenacola Mesa Redondo Mesa, Alamos Canyon, and surrounding areas.
Within the MSHCP Conservation Area, determine if successful reproduction is occurring as measured by the presence/absence of tadpoles, egg masses, or juvenile frogs once a year for the first five years after permit issuance and then as determined by the Reserve Management Oversight Committee as described in Section 6.6, MSHCP Volume I (but not less frequently than every 8 years).
For purposes of this conservation analysis, potential habitat for the California red-legged frog includes relatively deep (>0.7 meter deep), cool pools or ponds with emergent and submergent vegetation and associated uplands. Vernal pools and alkali playas have been mapped to a certain extent within the MSCHP plan, but are only used for this analysis within the Santa Rosa Plateau and southern Santa Ana Mountains. This is because red-legged frogs also use stock ponds and streams with suitable characteristics, therefore conservation based on vernal pool coverage alone is not appropriate. Instead, species coverage must be primarily based on population preservation and suitable occupied and potential habitat preservation within historically occupied areas.
The Plan Area supports approximately 813 acres of land which is determined to be primary breeding habitat and includes both occupied and historically occupied suitable breeding habitat. The Plan Area also supports approximately 48,518 acres of secondary upland movement habitat. As stated below under Data Characterization and Key Populations, suitable breeding habitat is described over the Santa Rosa Plateau, southern Santa Ana Mountains (San Mateo Wilderness area of the Cleveland National Forest) and intermediate areas around Rdonda Mesa, Avenacola Mesa, Squaw Mountain, and Los Alamos Canyon. As shown in Table 1, suitable primary habitats preserved include riparian scrub, woodlands, and forests; open water; playas and vernal pools, and; alluvial fan scrubs. Suitable upland habitats (Table 2) include chaparral; coastal sage scrub; woodlands and forests, and; grasslands. Overall, approximately 766 acres (94 percent) of suitable primary occupied and potential historical breeding habitat and 39,147 acres (81 percent) of suitable secondary upland movement habitat (39,913 acres total [81 percent]) will be conserved in the MSHCP Conservation Area. It is assumed that these lands would be managed for wildlife resources including the California red-legged frog.
TABLE 1
SUMMARY OF PRIMARY HABITAT CONSERVATION
FOR THE CALIFORNIA RED-LEGGED FROG
| Within MSHCP Conservation Area | Outside MSHCP Conservation Area | ||||||
|---|---|---|---|---|---|---|---|
| Vegetation Type | Plan Area1 (Acres) | Criteria Area2 (Acres) | Public/ Quasi-Public (Acres) | Total Within MSHCP Conservation Area (Acres) | Rural/ Mountainous (Acres) | Outside MSHCP Conservation Area (Acres) | Total Outside MSHCP Conservation Area (Acres) |
| Playas and Vernal Pools | 32 | 1 | 31 | 32 | 0 | 0 | 0 |
| Riparian Scrub, Woodland and Forest | 773 | 34 | 699 | 733 | 37 | 3 | 40 |
| Riversidean Alluvial Fan Sage Scrub | 1 | 0 | 1 | 1 | 0 | 0 | 0 |
| Open water | 7 | 0 | 0 | 0 | 7 | 0 | 7 |
| TOTAL | 813 | 35 | 731 | 766 | 44 | 3 | 47 |
| 1 Includes occupied, historically occupied, and other proximate suitable breeding habitat within Santa Rosa Plateau, southern Santa Ana Mountains, and potential movement areas between them. 2 Acres refer to Additional Reserve Lands to be assembled from within the Criteria Area. |
|||||||
TABLE 2
SUMMARY OF SECONDARY HABITAT CONSERVATION
FOR THE CALIFORNIA RED-LEGGED FROG
| Within MSHCP Conservation Area | Outside MSHCP Conservation Area | ||||||
|---|---|---|---|---|---|---|---|
| Vegetation Type | Plan Area1 (Acres) | Criteria Area2 (Acres) | Public/ Quasi-Public (Acres) | Total Within MSHCP Conservation Area (Acres) | Rural/ Mountainous (Acres) | Outside MSHCP Conservation Area (Acres) | Total Outside MSHCP Conservation Area (Acres) |
| Agricultural Land | 301 | 6 | 3 | 9 | 280 | 12 | 292 |
| Chaparral | 36,643 | 495 | 30,993 | 31,488 | 4,411 | 744 | 5,155 |
| Coastal Sage Scrub | 1,185 | 34 | 991 | 1,025 | 139 | 21 | 160 |
| Grassland | 6,721 | 338 | 3,971 | 4,309 | 2,256 | 156 | 2,412 |
| Woodlands and Forest | 3,668 | 117 | 2,199 | 2,316 | 1,246 | 106 | 1,352 |
| TOTAL | 48,518 | 990 | 38,157 | 39,147 | 8,332 | 1,039 | 9,371 |
| 1 Includes occupied, historically occupied, and other proximate and interstitial upland movement habitat within Santa Rosa Plateau, southern Santa Ana Mountains, and potential movement areas between them. 2 Acres refer to Additional Reserve Lands to be assembled from within the Criteria Area. |
|||||||
As described below under Data Characterization, there are only seven current data points for the MSHCP Plan Area that are precise and recent enough for evaluation; all of which occur on the Santa Rosa Plateau within Public/Quasi-Public Land designations. These data points are thought to define the population within western Riverside County.
Two key core habitat blocks are conserved under the Plan. The Santa Rosa Plateau population area (Existing Core F; 9,028 acres) and the southern Santa Ana Mountains U.S. Forest Service area (southern portion of Existing Core B; 30,964 acres), are connected by a wide (2- to 3-mile wide) linkage/habitat block area (10,334 acres). This runs through approximately 4 miles of non-reserve and non-public/quasi-public, rural/mountainous land. Maintaining viable connectivity between the two MSHCP Conservation Areas within non-reserve areas will be crucial to maintaining successful existing and re-introduced populations. The Cleveland National Forest protects much of the Los Alamos Creek watershed within the San Mateo Canyon Wilderness and the Santa Rosa Plateau population/suitable habitat is protected by the Santa Rosa Plateau Ecological Reserve.
Implementation of the MSHCP, including the conservation of the existing populations and suitable habitat as described above, will maintain viable populations of the California red-legged frog and facilitate recovery of the species. The current distribution is thought to be known, however some areas which may support the frog are relatively inaccessible and are visited sporadically at best. However, surveying for existing and new populations is relatively easy if access is available. Ensuring that the species remains viable in the MSHCP Plan Area will require a systematic monitoring program.
In summary, conservation for the California red-legged frog will be achieved by the inclusion of at least 39,913 acres of suitable Conserved primary breeding Habitat and Conserved secondary upland Habitat within 2 Core Areas which are composed of large blocks of habitat within the MSHCP Conservation Area. The Core Areas are connected by a large interstitial area which has small drainages and large upland areas which will need to be protected as they are determined to be important to red-legged frog. In addition, surveys for this species will be conducted as part of the project review process for public and private projects within the amphibian species survey area where suitable habitat is present (see Amphibian Species Survey Area Map, Figure 6-3 of the MSHCP, Volume I). Red-legged frog locations identified as a result of survey efforts shall be conserved in accordance with procedures described within Section 6.3.2, MSHCP, Volume 1. Other species survey requirements associated with the MSHCP are documented in Sections 6.1.2 and 6.1.3. A complete summary of all MSHCP species survey requirements is provided in Appendix E of Volume I. Within the MSHCP Conservation Area, Reserve Managers shall maintain or, if feasible, restore ecological processes within occupied habitat and suitable new areas within the reserve. At a minimum, these areas will include the Santa Rosa Plateau, San Mateo Wilderness area of the Cleveland National Forest, Squaw Mountain, Avenacola Mesa Redondo Mesa, Alamos Canyon, and surrounding areas. Within the MSHCP Conservation Area, Reserve Managers shall determine if successful reproduction is occurring as measured by the presence/absence of tadpoles, egg masses, or juvenile frogs once a year for the first 5 years after permit issuance and then as determined by the Reserve Management Oversight Committee (but not less frequently than every 8 years). Furthermore, the Plan Area is contiguous with suitable habitat in Orange and San Diego counties.
Incidental Take of the California red-legged frog is difficult to quantify due to a relative lack of species occurrence data. However, the maximum level of Take of the red-legged frog can be anticipated by the loss of the number of acres of habitat that will become unsuitable for this species, and individuals within these areas will be subject to Incidental Take consistent with the Plan. Approximately 47 acres (6 percent) of probable suitable primary breeding habitat and 9,371 (19 percent) of suitable secondary upland movement habitat (9,418 acres total [19 percent]), would be located outside the MSHCP Conservation Area.
The California red-legged frog is currently restricted to pool complexes on the Santa Rosa Plateau Ecological Reserve. The only known population within the Plan Area is comprised of a couple of males on the Santa Rosa Plateau. The species was federally-listed in May 1996 (U.S. Fish and Wildlife Service 1996) and final Critical Habitat was designated in March 2001 (U.S. Fish and Wildlife Service 2001). Abundant information exists in the literature, for the red-legged frog. However, there is no information available regarding genetics, survivorship, dispersal, and socio-spatial behavior. The MSHCP data base holds 22 records for R. a. draytonii. Of the 22 records, 7 (32 percent) are precision code "1" (an "x" and "y" coordinate that allows for good precision in the location), 5 (23 percent) are precision code "2" (one "x" or "y" data point or equivalent), and 10 (46 percent) "3" or "4" (relatively imprecise locations from general areas). Five of the Precision code "1" records are from 1998, one from 1997, and one precision code "2" record from 1995. These are considered to be the only recent records.
The California red-legged frog inhabits lowland streams, wetlands, riparian woodlands, and livestock ponds (Hayes and Jennings, 1988; Jennings, 1988). The species may also occur in uplands near breeding areas and along intermittent drainages connecting wetlands. The adults often use dense, shrubby or emergent riparian vegetation closely associated with deep (>0.7 meters), still or slow moving water (Hayes and Jennings, 1988). Red-legged frogs require cold water pond habitats (including stream pools) with emergent and submergent vegetation (Storer, 1925).
Habitats with the highest densities of frogs are deep water ponds with dense stands of overhanging willows (Salix sp.) and a fringe of cattails (Typha latifolia) between the willow roots and overhanging willow limbs (Jennings 1988; Rathburn, et al., 1993). Red-legged frogs are closely tied to plunge pool habitats next to willows (Hayes and Jennings, 1988). California red-legged frogs have also been found in association with stock ponds throughout its range, wildlife "guzzlers," marsh habitat, and can occur in ephemeral ponds or permanent streams and ponds, however populations probably cannot persist in ephemeral streams (Jennings and Hayes, 1985).
California red-legged frogs appear to be more closely tied to small drainage areas (<300km2) and their intermittent water flow as opposed to large drainage areas (>300km2) and their perennial water flow, due to restricted access by aquatic macrofaunal predators (Hayes and Jennings, 1988). Two thirds of their localities are from drainage areas < 40 square kilometers and they were most frequently recorded at sites having a low local gradient, and in streams having a low stream order. Hayes and Jennings (1988) reported that red-legged frogs have been recorded in 1st to 6th order streams, but 94 percent (n=115) are 4th or lesser-order streams and 42 percent are 1st order streams. Good water quality is also important (Jennings, 1988; Bradford et al., 1994) and water salinity should be at or below 4.5 percent to ensure survival of embryonic stages (Hayes and Jennings, 1988).
According to Jennings and Hayes (1985), the historic range of the California red-legged frog extends through Pacific slope drainages from the vicinity of Redding (Shasta County: Storer, 1925) inland and to Point Reyes (Marin County), California (coastally) southward to the Santo Domingo River drainage in Baja California, Mexico. It has also occupied habitat in a few desert slope drainages in southern California (Jennings and Hayes, 1994). Currently, a large number of California red-legged frogs are only found in coastal fog belt localities; most inland populations appear to be extirpated (Jennings, 1991).
Significant breeding populations (>350 adults) are currently known at Pescadero Marsh Natural Preserve, Point Reyes National Seashore, and the canals west of the San Francisco Airport. In southern California, south of Ventura to the Mexican border, only one population (Santa Rosa Plateau Preserve) is protected. Introduced populations occur in central southern Nevada (Green, 1985). An introduced population also occurred on Santa Cruz Island (Jennings, 1988). The species is known from sea level to approximately 1,500 meters.
The red-legged frog is very rare in Riverside County. One small population occurs on the Santa Rosa Plateau which consists of four males and one female. During the spring of 1998 the female was not observed (Scott Harris, CDFG, pers. comm.). The Santa Rosa Plateau (Cole Creek) population is the only known population within western Riverside County. This population is the only known extant population south of Ventura County.
The currently known extant population includes three individuals located at the Santa Rosa Plateau Ecological Reserve. Other historical or suspected locations include the vicinity of Temescal, Vail Lake, Kolb Creek, Murrieta Creek, Santa Ana River, Santa Ana Mountains, Anza, Glen Ivy, Pedley, and the City of Riverside.
On March 2001, the USFWS issued a proposal the final designated critical habitat for this species. The only area within the Plan Area is situated on and around the Santa Rosa Ecological Reserve. Specifically, it includes portions of the Reserve, the Santa Rosa Plateau, and the southern extent of the Santa Ana Mountains including portions of DeLuz Creek, Murrieta and San Mateo Canyon watersheds. Sixty-six percent is managed by the USFS, the rest is privately owned or managed by the State of California.
Genetics: There is no available information regarding genetics.
Diet and Foraging: After examining the digestive contents of 35 red-legged frogs, Hayes and Tennant (1985) found that the most frequently encountered prey groups were carabid and tenebrionid beetles, water striders (Gerridae), lycosid spiders, and larval neuropterans. The most frequently encountered prey species were larval alderflies (Sialis californica), pillbugs (Aramadillidium vulgare), and water striders (Gerris sp.). Algae is probably the food item eaten by larvae (Jennings et al., 1992). Small vertebrates such as Pacific tree frogs (Pseudacris regilla) and California mice (Peromyscus californicus) represented over half the prey mass eaten by larger frogs and were found to be the largest prey items in Hayes and Tennant's sample. As expected, the data suggest that a greater range of prey sizes is available to larger frogs. A large female red-legged frog was observed swallowing a California mouse by pressing it against the substrate and using its forelimbs. This resulted in the frog's ingestion of a considerable amount of sand with the prey item.
Hayes and Tennant (1985) emphasize that prey composition appears largely influenced by variation in habitat. Their observations indicate that frogs appeared to recognize potential prey by continuous movement. Dickerson (1906) stated that the red-legged frog can take prey underwater, emphasizing its cannibalistic nature and fish-eating habits in addition to its diet of aquatic and terrestrial insects, tadpoles, worms, and a preference for sow bugs. Feeding was observed during both day and night time for juveniles, but only at night for adults and sub-adults.
Daily Activity: California red-legged frogs found in coastal areas are rarely inactive (Jennings et. al., 1992), whereas those found at interior sites may hibernate (Storer, 1925). R. a. draytonii may estivate in small mammal burrows and moist leaf litter, and can be found up to 30 meters from water in adjacent dense riparian vegetation for up to 77 days (Rathburn, et al., 1993). Adults are largely nocturnal, whereas juveniles can be active either diurnally or nocturnally (Hayes and Tennant, 1985; Jennings, 1988). In addition, time of feeding does not differ from time of activity for either adults or juveniles, suggesting that juveniles have a broader range of activity and probably longer feeding periods than adults or sub-adults.
Reproduction: R. a. draytonii breed from November through April, with earlier breeding records occurring in southern localities (Storer, 1925). R. a. draytonii can only reproduce when conditions are optimal, and consequently, this taxon is an explosive breeder. Within a narrow window (1-3 weeks) between late December and early April, females normally lay loose, oval, floating egg clusters of about 2,000-5,000 eggs in quite waters (Storer, 1925). Egg masses are generally attached to vertical emergent vegetation so that they are near the surface of the water (Hayes and Miyamoto, 1984). Eggs hatch in 6-14 days (Jennings, 1988), and metamorphosis occurs 3.5 to 7 months after hatching (Storer, 1925; Jennings and Hayes, 1990). There is no evidence to suggest that they lay more than one clutch per year like some eastern ranids (e.g., see Emlen, 1977).
Developing eggs and embryos of this taxon are unable to survive salinities of >4.5 0/00 (Hayes and Jennings, 1988) and probably temperatures >21 degrees Celsius [this figure is based on the critical thermal maximum for closely related R. a. aurora (Licht, 1971)]. Larvae require cold water (<18.3 degrees Celsius) to develop properly (Jennings, 1988); and likely experience the highest mortality rates, with less than 1 percent of eggs laid reaching metamorphosis (Jennings et al., 1992). Two years after metamorphosis, males reach sexual maturity, while females require three years to attain sexual maturity (Jennings and Hayes, 1985). R. a draytonii may live up to 10 years (Jennings et al., 1992).
Survival: Survival rates for red-legged frogs from hatching to metamorphosis range from one to less than five percent for frogs co-occurring with bullfrogs and 30 to 40 percent for those without bullfrogs (USFWS 2000). Adults live 8 to 10 years (USFWS 2000).
Dispersal: According to USFWS 2000, red-legged frogs can be found living in streams away from breeding habitat and distances exceeding 2.9 km and have ben found over 100 m away from water in dense riparian vegetation. During wet weather, some frogs make overland excursions over upland habitat, mostly at night. Movements ranging from 0.4 to over 3.2 km are known to occur without regard to topography or vegetation type. Frogs may or may not use riparian corridors for movements, instead they may move directly to their goal. Juveniles may disperse locally between July and September.
Socio-Spatial Behavior: There is no available information.
Community Relationships: Hayes and Jennings' data (1988) reveal that R. a. draytonii was more frequently found at sites with native fishes and with substrate alteration (at least 25 percent of either direct or indirect impact by humans (e.g., rip-rap, vegetation removal, trampling of banks by cattle, etc.), and less frequently at sites with introduced fish. At 52 sites that supported R. a. draytonii in the central valley of California, the most frequently co-occurring native fish species were the California roach (Lavinia symmetricus; present at 47 percent of examined sites), hitch (Lavinia exilicauda; present at 25 percent of examined sites), green sunfish (Lepomis cyanellus; present at 15 percent of examined sites), and mosquitofish (Gambusia affinis; present at 15 percent of examined sites) (Hayes and Jennings, 1988).
The California red-legged frog has sustained a 70 percent reduction in its geographic range in California as a result of habitat loss or alteration due to over-collecting, introduced predators, reservoir construction, stream channelization, urbanization, overgrazing, and drought (Jennings, 1988). More specifically, any projects within suspected habitats of the species that affect suitable stream and wetland habitats, as well as adjacent upland areas, could result in significant impacts to the species. Examples of projects in western Riverside County that could result in a significantly negative impact on this species include a wide range of water management activities, including construction, operation, and maintenance activities associated with dams and reservoirs, irrigation diversion activities, wastewater discharge, flood control, and aggregate mining activities (Fisher and Shaffer, 1996). Pesticides, herbicides and lead can negatively affect frogs and other amphibians. Predation by introduced fishes (Jennings, 1988; Moyle, et al. 1986; Hayes and Jennings, 1986), bullfrogs (Jennings and Hayes, 1985; Hayes and Jennings, 1986), and crayfish, as well as disease (Jennings and Hayes 1988), and parasites (Lefcort and Blaustein, 1995) all have been known to affect red-legged frog populations. Catastrophic events, and recreational activities also can contribute to the decline of R. a. draytonii.
Long-term cumulative effects of multiple factors are usually the cause of the declines such as these. When natural low points in amphibian population cycles synergize with widespread environmental alterations, extinction events occur. Because true frogs fit classic models of metapopulation dynamics, they are uniquely vulnerable to these cumulative environmental effects. Typically, disjunct populations undergo continuous cycles of extinction and recolonization from nearby sources (see Harrison, 1991). Such recolonization events are now impossible for many native frogs in the Sierra Nevadas because of the introduction of predatory fishes in formerly suitable habitats and the widespread extinction of many local source frog populations (Bradford, et al. 1993).
The rapid decline of the red-legged frog over most of its historic range has not been prevented by State protection which has been provided since 1971. The required habitat of the red-legged frog (Riparian habitats with deep pools) has been severely reduced by drought and land use practices over the past 50 years throughout California. This has resulted in habitat less suitable for reproduction and survival for the species. Jennings (1991) cited the following niche-specific effects resulting from the above practices: (1) creation of lotic warm water microhabitats; (2) the removal of native streamside vegetation which allows the growth of emergent vegetation; (3) modification of riparian zones which allows increased solar input, thus raising ambient temperatures and providing access for predators of all life stages; and (4) reducing or elimination of undercut banks, underwater holes, tree root masses, and gravel substrates by increased erosion and siltation.
Immediate management considerations need to be applied to R. a. draytonii if the remaining or suspected populations are to remain viable. The goal of management should be to isolate the taxon from introduced predators (Hayes and Jennings, 1988). In addition, preservation of modal conditions for habitat variables identified as associated with the species is likely to promote isolation and would be a suitable interim strategy (Hayes and Jennings, 1988).
Although exploitation as food has been linked to the historical disappearance of red-legged frogs (Hayes and Jennings, 1986, 1988), the severe decline in the population since the mid-1970's, despite unperceived changes in habitat, remain poorly understood (Jennings, 1991). Wernette et. al. (1982) reported that over half of the remaining populations are located in areas projected to be flooded by reservoirs proposed for the Coast Range slope of the Central Valley. Six years after Wernette's, et. al. 1982 report, Hayes and Jennings (1988) reported that R. a. draytonii had become extinct on the floor of the Central Valley, and was probably extinct from over half of the drainage systems in the Central Valley from where it was historically recorded.
The recent USFWS final critical habitat document (USFWS 2001) states that critical habitat will provide breeding and non-breeding habitat for dispersal between the habitats and also allows for expansion fo red-legged frog populations. The proposal continues to state the primary constituent elements of critical habitats: (1) suitable aquatic habitat, (2) associated upland habitats; and (3) suitable dispersal habitat connecting suitable aquatic habitat. Suitable aquatic habitat is defined as all natural or man-made still or slow-moving freshwater bodies that are void of non-native predators and are year-round. Suitable breeding water bodies must have a minimum water depth of 8 inches and maintain water levels from March through July at a minimum. There must be 2 or more breeding sites within 2 km. Suitable upland habitats include all upland habitats within 150 m of the edge of suitable aquatic habitat. Suitable dispersal habitat must be free of barriers and at least 150 m wide. Dispersal corridors include upland and wetland habitats which are free of barriers and connect suitable aquatic habitat within 2 km of one another. Dispersal barriers are defined as heavily traveled roads (more than 30 cars per hours), moderate to high density urban or industrial developments, and large reservoirs. Agricultural lands and pastures are not barriers.
Bradford, D.F., M.S. Gordon, D.F. Johnson, R.D. Andrews, and W.B. Jennings. 1994. Acidic deposition as an unlikely cause for amphibian population declines in the Sierra Nevada, California. Biological Conservation 69(2):155-61.
Bradford, D.M. Graber, and F. Tabatabai. 1993. Isolation of remaining populations of the native frog, Rana mucosa, by introduced fish in Sequoia and Kings Canyon National Parks, California. Conservation Biology 7(4):882-88.
Dickerson. 1906. The frog book. Doubleday, Page and Co., New York.
Emlen, S.T. 1977. "Double clutching" and its possible significance in the bullfrog. Copeia, 1977(4):749-751.
Fellers, G.M. and C.A. Drost. 1993. Disappearance of the Cascades frog, Rana cascadae at the southern end of its range, California, USA. Biological Conservation 65(2): 177-81.
Fisher, R.N. and H.B.Shaffer. 1996. The decline of amphibians in California's great central valley. Conservation Biology 10: 1387-1397.
Green, D.M. 1985. Differentiation in amount of centromeric heterochromatin between subspecies of the red-legged frog rana-aurora. Copeia 1985: 1071-1074.
Harris, Scott. 1999. Personal Comment.
Harrison, S. 1991. Local extinction in a metapopulation context: An empirical evaluation. Biological Journal of the Linnean Society 42(1&2):73-88.
Hayes, M.P. and M.R. Jennings. 1986. Decline of ranid frog species in western North America: are bullfrogs (Rana catesbeiana) responsible? J. Herpetology, 20(4):490-509.
Hayes, M. P., and M. R. Jennings. 1988. Habitat correlates of distribution of the California red-legged frog (Rana aurora draytonii) and the foothill yellow-legged frog (Rana boylii): Implications for management. Pages 144-158 In: R. Sarzo, K. E. Severson, and D. R. Patton (technical coordinators). Proceedings of the Symposium on the Management of Amphibians, Reptiles, and small mammals in North America. U.S.D.A. Forest Service General Technical Report RM-166.
Hayes, M. P., and M. M. Miyamoto. 1984. Biochemical, behavioral and body size differences between Rana aurora aurora and R. a. draytonii. Copeia 1984(4):1018-1022.
Hayes, M. P., and M. R. Tennant. 1985. Diet and feeding behavior of the California red-legged frog, Rana aurora draytonii (Ranidae). The Southwestern Naturalist 30(4):601-605.
Jennings, M. R. 1988. Natural History and decline of native ranids in California. Pages 61-72 In: H. F. DeLisle, P. R. Brown, B. Kaufman, and B. M. McGurty (editors). Proceedings of the conference on California herpetology. Southwest Herpetologists Society, Special Publication (4):1-143.
Jennings, M. R., and M. P. Hayes. 1990. Status of the California red-legged frog (Rana aurora draytonii): The inducement of bullfrog (Rana catesbeiana) introduction. Herpetologica 41(1):94-103.
Jennings, M.R. and M.P. Hayes. 1985. Pre-1900 overharvest of California red-legged frog (Rana aurora draytonii): The inducement for bullfrog (Rana catesbeiana) introduction. Herpetologica, 41(1):94-103.
Jennings, M. R., M. P. Hayes, and D. C. Holland. 1992. A petition to the U.S. Fish and Wildlife Service to place the California red-legged frog (Rana aurora draytonii) and the western pond turtle (Clemmys marmorata) on the list of endangered and threatened wildlife and plants. 21 pp.
Jennings, M.R. 1991. Preliminary Summary of Information Regarding Four Species of Potentially Endangered Amphibians in Southern California. California Academy of Sciences. Department of Herpetology. San Francisco, California.
Jennings, M.R. 1996. Sierra Nevada Ecosystem Project: Final report to Congress, vol. II. Assessments and scientific basis for management options. Davis: Univ. of California, Centers for Water and Wildland Resources. Ch 31. Status of Amphibians.
Lefcort, H. and A.R.Blaustein. 1995. Disease, predator avoidance, and vulnerability to predation in tadpoles. Oikos 74: 469-474.
Licht, L.E. 1971. Breeding habits and embryonic thermal requirements of the frogs, Rana aurora aurora and Rana pretiosa pretiosa, in the Pacific Northwest. Ecology, 52(1):116-124.
Moyle, P.B. and H.W.Li and B.A.Barton. 1986. The Frankenstein effect: impact of introduced fishes on native fishes in North America. in Fish culture in fisheries management, edited by R.H.Stroud (Bethesda, Maryland: American Fisheries Society), pp. 415-26.
Rathburn, G.B., M. R. Jennings, T. G. Murphy, and N. R. Siepel. 1993. Status and ecology of sensitive aquatic vertebrates in lower San Simeon and Pico creeks, San Luis Obispo County, California. U.S. Fish and Wildlife Service, National Ecology Research Center, San Simeon, California. Prepared for the California Department of Parks and Recreation. 103 pp.
Stebbins, R. C. 1985. A field guide to western reptiles and amphibians. Houghton Mifflin Company, Boston, MA. 336 pp.
Storer, T. I. 1925. A synopsis of the amphibia of California. University of California Publications in Zoology 27:1-342.
U.S. Fish and Wildlife Service. Federal Register 61: 25832, May 23, 1996.
U.S. Fish and Wildlife Service. September 11, 2000. Federal Register 65:54892.
Wernette, F.G., F.A. Hall Jr., C.J. Brown Jr., C.L. Mayer, and N.A. Villa. 1982. Los Vaqueros project- fish and wildlife impacts. 263 p. California Department of Fish and Game, Status Report.
coast range newt (Taricha tarosa tarosa)
State: Species of Special Concern (CDFG)
Federal: None
The coast range newt has narrow habitat requirements and limited distribution within the Plan Area, typically being restricted to "pools and runs" stream configurations and adjacent upland habitats within the Santa Ana Mountains Bioregion. Currently, the known distribution of coast range newt within the Plan Area is restricted to the Santa Ana Mountains. Because the coast range newt requires very specific breeding habitat conditions, only occurs within a few locations, and uses a well defined habitat that is narrowly distributed, this species will require site specific considerations, protection of primary breeding habitat and adjacent upland areas, and species-specific conservation measures.
The species-specific conservation objectives developed for this species are based upon the best available scientific information at the time of MSHCP preparation. Pursuant to Section 5.0 which includes Management, Monitoring and the Adaptive Management Program, the MSHCP's mitigation requirements will be monitored and analyzed to determine if they are producing the desired result. Based upon this information, the following species-specific conservation objectives will be adjusted if appropriate, as new information is gathered during Plan implementation. The Adaptive Management Program will be used to identify alternative strategies for meeting the MSHCP's general biological goals and objectives and, if necessary, adjusting future conservation strategies according to the information received.
Include within the MSHCP Conservation Area at least 8,441 acres of primary breeding habitat (playa and vernal pools, riparian scrub, woodland, and forest, and water) within the Santa Ana Mountains bioregion. Within the greater habitat categories, coast range newt breeding activities are limited to streams and creeks which may form "pool and runs" hydrology.
Include within the MSHCP Conservation Area at least 76,579 acres of the secondary habitat (chaparral, coastal sage scrub, grassland, Riversidean alluvial scrub, and oak woodlands and forests) within the Santa Ana Mountains Bioregion. Secondary habitat is limited to a 2 km buffer around streams and creeks.
A 100-meter buffer, where possible, will be established around emergent vegetation areas identified in Objective 1 as they are incorporated into the MSHCP Conservation Area for water quality purposes.
Within the MSHCP Conservation Area, Reserve Managers shall maintain or, if feasible, restore ecological processes within occupied habitat and suitable new areas within the MSHCP Conservation Area. At a minimum, these areas will include creeks, streams, ponds, and other wetland habitat in the Cleveland National Forest (Santa Ana Mountains Bioregion) and Santa Rosa Plateau (includes portions of Cole Creek).
Within the MSHCP Conservation Area, maintain occupancy of at least 75 percent of the occupied coast range newt habitat and determine if successful reproduction is occurring within the MSHCP Conservation Area as measured by the presence/absence of larvae or egg masses once a year for the first five years after permit issuance and then as determined by the Reserve Management Oversight Committee as described in Section 6.6, MSHCP Volume I (but not less frequently than every 8 years).
For purposes of this conservation analysis, suitable habitat for the coast range newt includes most upland habitats and water bodies within the Santa Ana Mountains Bioregion below an 1,830 m elevation. Specifically, breeding habitat is associated with "pools and runs" stream courses (i.e., playa and vernal pools, riparian scrub, woodland and forest, and water), and secondary upland habitat consists of adjacent uplands within 2 kilometers of stream courses (i.e., chaparral, coastal sage scrub, grasslands, Riversidean alluvial sage scrub, and oak woodlands and forests). Because of the apparently abundant seasonal streams available within the Santa Ana Mountains Bioregion, the entire Bioregion is considered to act as suitable secondary upland habitat. Because there are very few data points, and most of the points that are available are old or undated, species coverage must be primarily based on suitable habitat preservation within the Santa Ana Mountains Bioregion. As described below under Data Characterization, there is only one current data point for the Plan Area that is precise and recent enough for evaluation, however this and the other points are all located within the Santa Ana Mountains. These data points are thought to roughly define the limits of the population within western Riverside County. This data is presented in Tables 1 and 2 below.
TABLE 1
SUMMARY OF PRIMARY HABITAT CONSERVATION
COAST RANGE NEWT
| Within MSHCP Conservation Area | Outside MSHCP Conservation Area | ||||||
|---|---|---|---|---|---|---|---|
| Vegetation Type | Plan Area1 (Acres) | Criteria Area2 (Acres) | Public/ Quasi-Public (Acres) | Total Within MSHCP Conservation Area (Acres) | Rural/ Mountainous (Acres) | Outside MSHCP Conservation Area (Acres) | Total Outside MSHCP Conservation Area (Acres) |
| Playas and Vernal Pools | 31 | 0 | 31 | 31 | 0 | 0 | 0 |
| Riparian Scrub, Woodland and Forest | 1,287 | 123 | 933 | 1,056 | 175 | 55 | 230 |
| Water | 37 | 1 | 0 | 1 | 23 | 14 | 37 |
| Woodlands and Forest | 11,099 | 981 | 6,372 | 7,353 | 3,219 | 525 | 3,744 |
| TOTAL | 12,456 | 1,107 | 7,304 | 8,441 | 3,417 | 595 | 4,011 |
| 1 Total acres only include Santa Ana Mountains Bioregion. 2 Acres refer to Additional Reserve Lands to be assembled from within the Criteria Area. |
|||||||
TABLE 2
SUMMARY OF SECONDARY UPLAND HABITAT CONSERVATION
COAST RANGE NEWT
| Within MSHCP Conservation Area | Outside MSHCP Conservation Area | ||||||
|---|---|---|---|---|---|---|---|
| Vegetation Type | Plan Area1 (Acres) | Criteria Area2 (Acres) | Public/ Quasi-Public (Acres) | Total Within MSHCP Conservation Area (Acres) | Rural/ Mountainous (Acres) | Outside MSHCP Conservation Area (Acres) | Total Outside MSHCP Conservation Area (Acres) |
| Chaparral | 85,516 | 3,458 | 62,480 | 65,938 | 16,599 | 2,978 | 19,577 |
| Coastal Sage Scrub | 12,506 | 342 | 5,007 | 5,349 | 6,238 | 918 | 7,156 |
| Grassland | 10,297 | 743 | 4,338 | 5,081 | 4,338 | 877 | 5,215 |
| Riversidean Alluvial Fan Sage Scrub | 334 | 142 | 69 | 211 | 26 | 95 | 121 |
| TOTAL | 108,653 | 4,685 | 71,894 | 76,579 | 27,201 | 4,868 | 32,069 |
| 1 Total acres only include Santa Ana Mountains Bioregion area. 2 Acres refer to Additional Reserve Lands to be assembled from within the Criteria Area. |
|||||||
Based on these habitats, the Plan Area within the Santa Ana Mountains Bioregion supports approximately 121,109 acres of potential habitat for the newt. Approximately 8,441 acres (68 percent) of primary wetland (breeding) habitat and 76,579 acres (70 percent) of secondary upland habitat would be conserved within the MSHCP Conservation Area. It is assumed that these lands would be managed for wildlife resources, including the coast range newt. Management actions will be incorporated into the conservation strategy so that habitat conditions will be maintained.
As described below under Data Characterization, all data points are considered too few and mostly too old, therefore preservation based on species occurrence is not feasible. All data points and known locations are situated within the Santa Ana Mountains Bioregion. Regardless, 4 (57 percent) of 7 precision code "1" or "2" data points will remain within the MSHCP Conservation Area, including the only recent data point from 1995. A review of various roadless areas and range allotments indicates the following: The Cleveland National Forest has portions of four roadless areas (Ladd, Coldwater, Trabuco, and Wildhorse) that occur from the vicinity of Corona south to the vicinity of Sedco Hills, and; portions of three cattle ranges (El Cariso, Verdugo, and Tenaja) occur between Lakeland Village and the Santa Rosa Plateau. Based on communications from the U.S. Fish and Wildlife Service, newts are also known from the Cole Creek area within the Santa Rosa Plateau Ecological Reserve and possibly to the northwest.
Only one large contiguous block of habitat supporting the coast range newt is present within the MSHCP Plan Area. This area is located in the Santa Ana Mountains, primarily on U.S. Forest Service land and the Santa Rosa Plateau Ecological Reserve. Protection is provided by the Forest Service and existing wetland regulations and the Plan's wetland policies. Management of watersheds will be important in maintaining breeding populations. Because newts are known to travel up to 2 km from breeding sites, connectivity between suitable breeding areas must be maintained. Very little is known about genetic relationships between coast range newts within the Plan Area. in order to retain important genetic variation, it is important to conserve representative populations at the limits of the species distribution and range, including longitude, latitude, and elevation. To this end, the Plan Area contains a relatively large and contiguous area with a wide elevational range within habitat that is suitable for the species.
The Forest Service will need to address development, hydrology maintenance, fish stocking practices, firewood harvesting, commercial timber harvesting, fire management, grazing leases, and land exchanges to avoid discussed threats to the species.
Implementation of the MSHCP, including the conservation of the existing population and suitable habitat as described above, will maintain viable populations of the Coast range newt. The current population size and local distribution of the coast range newt is unknown and censussing populations may be difficult due to steep terrain and habitat preferences of the species. Ensuring that the species remains viable in the MSHCP Plan Area will require a comprehensive management plan and general monitoring.
In summary, conservation for the coast range newt will be achieved by the inclusion of at least 8,441 acres of suitable primary Conserved Habitat and 76,579 acres of secondary upland Conserved Habitat within one Core Area (Santa Ana Mountains Bioregion) within the MSHCP Conservation Area. The Core Area provides connections between seasonally preferred habitats. In addition, the MSHCP Plan will maintain a 100-meter buffer around breeding habitat areas identified above; maintain or, if feasible, restore ecological processes within occupied habitat and suitable new areas within the MSHCP Conservation Area, minimally these areas will include creeks, streams, ponds, and other wetland habitat in the Cleveland National Forest (Santa Ana Mountains Bioregion) and Santa Rosa Plateau (includes portions of Cole Creek); and maintain occupancy of at least 75 percent of the occupied coast range newt habitat and determine if successful reproduction is occurring within the MSHCP Conservation Area, as measured by the presence/absence of larvae or egg masses once a year for the first five years after permit issuance and then as determined by the Reserve Management Oversight Committee. The current population size and distribution of the coast range newt is unknown. Furthermore, the Plan Area is contiguous with suitable habitat in Orange and San Diego counties.
Incidental Take of the coast range newt is difficult to quantify due to our limited knowledge of the species distribution within the Plan Area, and the fact that losses may be masked by fluctuations in abundance and distribution during the life of the permit. However, the maximum level of Take of the coast range newt can be anticipated by the loss of the number of acres of habitat that will become unsuitable for this species and individuals within these areas will be subject to Incidental Take consistent with the Plan. Approximately 4,011 acres (32 percent) of potential primary breeding habitat and 32,069 acres (30 percent) of secondary upland habitat for the coast range newt would be outside the MSHCP Conservation Area.
The coast range newt is restricted to the Santa Ana Mountains from the Santa Ana River to the Santa Margarita River, utilizing a variety of upland habitats but relying on bodies of water for breeding purposes. There is a moderate amount of information known about the western newt. The MSHCP data base holds 23 records for T. t. tarosa. Of the 23 records, 2 (8 percent) area precision code "1" (an "x" and "y" coordinate that allows for good precision in the location), 9 (39 percent) are precision code "2" (one "x" or "y" data point or equivalent), and 12 (31 percent) are precision code "3" or "4" (relatively imprecise locations from general areas). Both of the precision code "1" and seven of the precision code "2" records are undated. Only one precision code "2" is dated from 1990 to 2001 (1995). This is considered to be the only recent record. However, all data are considered pertinent and useful to conservation analysis.
T. t. tarosa frequents terrestrial habitats (grassland, woodland and forest) but breeds in ponds, reservoirs, and slow moving streams (Stebbins, 1985).
The western newt (T. t. torosa) ranges along the western coast of California from Humboldt County, to the Mexican border (Tan and Wake, 1995). Populations in southern California appear to exhibit a high level of historic fragmentation. The known elevation range of this taxon extends from near sea level to 1,830 meters. T. t. torosa has been depleted in southern California, including extirpation of the southern most populations in San Diego County. It is one of two species of California newt; the other being T. t. sierrae which is found in the Sierra Nevada Mountains.
T. t. torosa occurs in coastal drainages of the western most portions of Riverside County. Lands adjacent to Forest Service southeast of Lake Elsinore, and along Highway 74, and southwest of Corona. Southeast of Lake Norconian and west of Highway 15. Several known citations on Forest Service lands, and at the Santa Rosa Plateau.
Entire known range in western Riverside County including the Santa Ana Mountains from the Santa Ana River south to the Santa Margarita River.
Taxonomic Systematics: Newts of the genus Taricha form a monophylitic group of three species (Riemer, 1958). Earlier studies recognized more species, but the taxonomy has been stable since Riemer's study in 1958. Tan and Wake (1995) studied mtDNA sequences of the California newt to test the previous phylogeographic hypothesis of the two subspecies T. t. torosa and T. t. sierra. They found the southern sierrae cluster has an mtDNA lineage derived from the coastal torosa. Additionally, the southern and central populations of torosa displayed more differentiation than the northern populations, suggesting a longer independent history (Tan and Wake, 1995). Phylogenetically, this places the southern torosa more basal to both the northern torosa and southern sierrae clusters. Tan and Wake (1995) concluded that the Taricha torosa complex is composed of five clusters: three clusters of T. t. sierrae (northern, central and southern Sierra Nevada); and two clusters of T. t. torosa (southern coastal and central coastal). Furthermore, the data suggests that the sierrae taxon is diphyletic.
Diet and Foraging: Typically, newts feed on earthworms, insects, snails and other small invertebrates (Stebbins, 1972). Hanson, et al. (1994), reported the stomach contents of a single female newt captured in the Santa Monica Mountains. They found several insects including 2 coleopterans, 11 lepidopteran, and 1 plecopteran; 5 conspecific newt larvae and an intact nestling bird. Additionally, newts are known to cannibalize their own or conspecific's egg masses (Marshall, et al., 1990). The study conducted by Marshall et al. (1990) determined that the majority of intraspecific oophagy occurred in the female newt.
Daily Activity: T. torosa has been found to be active in all hours of the day (Marshall, et al., 1990). Much of its daily activity revolves around feeding, both in aquatic and terrestrial habitats. It has a well developed tongue-projection system for use in terrestrial feeding, and relies almost entirely on prey movement to detect food items. Without movement, prey within reach are ignored. Feeding consists of orientation and approach to prey, and the strike (Findeis and Bemis, 1990). An alert posture and elevated head characterize approach which is rapid. Within 5-10 mm of prey the newt halts and may shift position slowly in preparation of the strike. Successful strikes occur only when prey is directly in front of the newt's head and within 10 mm (Findeis and Bemis, 1990). At the instant the tongue is substantially deployed, the newt lunges forward to contact the tongue pad to the prey item and retract the item deep into the oral cavity. Findeis and Bemis (1990) found that in captivity, strikes were 56 percent successful with maggots as the prey item.
Reproduction: The mating season for the western newt occurs between January and May, depending on location (Stebbins, 1962; Twitty, 1942). The reproductive cycle begins with males migrating in large numbers to the breeding area. The preferred breeding and oviposition sites of T. torosa are the largest and deepest pools, and slow-moving runs available in streams (Gamradt and Kats, 1997). Prior to entering the water, males undergo physiological changes which adapt them to aquatic life and acquire secondary sex characteristics (i.e., skin becomes engorged with fluid and loses its rough texture, becoming highly vascularized; the tail develops a broad blade; and the cloacal lips become enlarged). Attractants released into the water by the female's skin attract males (Twitty, 1955). Movement also attracts attention at close range. Several males may be attracted to a single female, especially during the early part of the breeding season. At times a single female may become entangled in a compact mass of 20 or more males. Breeding occurs 24 hours a day (Marshall, et al., 1990).
After courting behaviors, the male deposits a spermatophore on the aquatic substrate. The spermatophore is composed of a gelatinous stalk with a rounded sperm mass perched on the apex. Once the spermatophore is in place, the male assumes the final courting position, orienting his hips away from the female in an arc, forming a deep lateral curvature of his pelvic region, with the concavity directed toward the female (Davis and Twitty, 1964). The female maintains her axial position to that of the male, moving sideways along the male''s flank until her snout penetrates the hollow of the sacral curvature, bringing her cloaca in close proximity to the spermatophore without any apparent visual guidance (Davis and Twitty, 1964). She then depresses her vent against the spermatophore to complete the ritual. After fertilization, females ovideposit 7-30 eggs (Brame, 1968), attaching them to the aquatic substrate. A female may take several weeks to deposit a single clutch (Marshall et al., 1990). In a study conducted by Gamradt and Kats (1997), 89 percent of egg masses observed were oviposited in pools and 9.5 percent were oviposited in runs of a stream in the Santa Monica Mountains.
Survival: Coast range newts are more resistant to desiccation due to their large bladder capacity, thick skin, high temperature tolerance, and frequent behavior of maintaining body contact with the substrate (Cohen, 1952; McFarland, 1955; Brattstrom, 1963; Brown and Brown, 1980). Their natural life span ranges from 10-15 years and they are very site tenacious (Twitty, 1942).
Stromberg (1997) documented a survival mechanism in response to a prescribed burn on the Hastings Natural History Reservation, Carmel Valley, Monterey Co., California. He observed a pair of newts walk through flames (5-10 cm high) without pausing. The slime covering their bodies foamed up, and within 20-30 seconds, they were through the flames and onto the ashes of the litter. Upon close examination, the now crusty white coating easily wiped off, and the skin was free of blisters or discoloration. He released the newts which continued to walk normally, proceeding at near record newt speed. As they walked, leaves and litter removed nearly all of the thin white crust covering their bodies. Foaming of the skin would dissipate heat and may be a mechanism used to escape natural wildfires (Stromberg, 1997).
Newt larvae have the ability to recognize the chemical cues of conspecific and native predators with which they have coevolved (i.e., snakes, raccoons, birds, coyotes, foxes; Diamond, 1996; Kats et al., 1994), but apparently this defense is ineffective against introduced predators such as mosquitofish and crayfish (Gamradt and Kats, 1996). The newt has the ability to repel some predators with toxic glands on its skin and eggs (Brodie et al., 1974). Adults produce a potent neurotoxin from dorsal skin, and when in the presence of predators display an Unken Reflex, curving the body upward to display the bright orange ventral skin. The bright ventral coloration of T. t. torosa is thought to be a warning to predators (Brodie, 1977).
Dispersal: Newts travel great distances relative to their body size (>1 km) during migrations between breeding sites and terrestrial habitats (Stebbins, 1951).
Socio-Spatial Behavior: The movement ecology of T. t. torosa is essentially unknown. Newts spend most of the year on land and typically engage in often lengthy (>1 km) overland migrations to breeding sites where breeding may occur between (December) January and April (Stebbins, 1951; Miller and Robbins, 1954). Electronically tagged newts have been found to return within a few meters of capture sites in subsequent years (Gamradt and Kats, 1997).
T. t. torosa has been depleted by large-scale historical commercial exploitation coupled with the loss and degradation of stream habitats, especially in Riverside and other south coastal counties (Jennings and Hayes, 1994). The breeding habitat of this taxon has been severely degraded over much of its range, largely due to a shift in sedimentation dynamics that has resulted in more filling and less scouring of pools (Jennings and Hayes, 1994).
By far, the largest threat to T. t. torosa is introduced crayfish (Procambarus clarkii) and mosquito fish (Gambusia affinis), as these exotic species are apparently unaffected by the potent neurotoxin produced by T. t. torosa. Data collected by Gamradt et al. (1997) indicates that aggression by crayfish directly affects newt behavior, breeding, and egg mass production.
Gamradt and Kats (1996) conducted a study on the effect of introduced predators on the western newt in the Santa Monica Mountains. Of the ten streams surveyed, three had mosquitofish and/or crayfish and contained no California newt eggs, larvae or adults. The remaining seven streams all contained California newts. In laboratory studies, they found that both predators studied prey on newt eggs and larvae, and that newt breeding behavior may be altered by predator presence, preventing successful mating and oviposition. Additionally, they found that in 1995, one stream was cleansed of crayfish by heavy rains. The following spring, the stream contained newt eggs where no evidence of newt presence was detected previously.
Wildfire is another threat to the western newt. Gamradt and Kats (1997) studied the effects of chaparral wildfire on Taricha torosa in a Santa Monica Mountain stream. They found major changes in stream morphology following the 1993 wildfire. The preferred habitat of the newt (pools and runs) was drastically reduced by landslides and sediment loads. The result was a drastic reduction in the amount of suitable habitat for oviposition. This likely occurred at two spatial scales: available oviposition microsites were covered with sediment and pool area decreased (Gamradt and Kats, 1997). Prior to the fire, pools and runs comprised 40-50 percent of the Plan Area. The following spring, the post-fire area contained less than 20 percent runs and pools; and approximately 1/3 the number of egg masses as compared to pre-fire surveys. Three years after the post-fire survey, the number of egg masses observed increased from 51 (1994) to 67 (1996), a possible indication that recovery had begun.
The continued policy driven release of mosquitofish will destroy the remaining populations of the western newt unless a management plan is implemented. Management should include the preservation of streams that are currently free from the introduced predator.
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