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HomeMy WebLinkAbout6 K-Rat and Pocket Mouse Survey 15 December 2017 SJMBC.976 W. Dean Brown The Planning Consortium 29422 Modjeska Canyon Road Silverado, CA 92676-9786 Subject: Results of a 2017 field habitat assessment to determine the potential presence of the federally endangered San Bernardino kangaroo rat (Dipodomys merriami parvus) (SBKR) on the approximately 7-acre Tentative Tract 20079, located in the San Sevaine Area of Rancho Cucamonga, California (Figures 1-3). Dear Mr. Brown: Following is a letter-report of a habitat assessment to determine the potential for occurrence of the SBKR at the project site mentioned above. INTRODUCTION AND SITE DESCRIPTION SBKR Background The SBKR, a member of the rodent Family Heteromyidae, is endemic to southwestern California. It is one of 19 subspecies of the Merriam’s kangaroo rat (Dipodomys merriami), which is widely distributed throughout the western United States and northwestern Mexico. Populations of SBKR historically ranged throughout alluvial floodplains and adjacent upland habitats, from the San Bernardino Valley in San Bernardino County to Menifee Valley in Riverside County. Twenty-five separate locations were identified by McKernan (1997) in San Bernardino and Riverside counties, four of which (City Creek, Etiwanda, Reche Canyon and South Bloomington) supported only small remnant populations. The Santa Ana River, Lytle and Cajon washes, and the San Jacinto River support the largest extant concentrations of SBKR and suitable habitat for this species (approximately 13,697 acres of potentially suitable habitat); however, all but 3,215 occupied acres are currently more mature than the open, early successional habitat type preferred by the SBKR (USFWS 1998a; USFWS 5-year review 2009). In response to habitat losses resulting from sand and gravel mining operations, flood control and water conservation projects, and urban and agricultural development, an emergency rule listing the SBKR as endangered was issued by the U.S. Fish and Wildlife Service (USFWS) on January 27, 1998, pursuant to the Endangered Species Act of 1973, as amended (USFWS 1998a). This emergency rule provided federal protection for this species for a limited time (expiring on September 24, 1998). The SBKR subsequently was listed as endangered on 24 September 1998 (USFWS 1998b). Much of the following summary of the status, distribution and various natural features of this species derive from the emergency and final rules. General natural history features and habitat requirements of the SBKR are relatively well known. The species is found primarily on sandy and sandy loam substrates, where they can readily excavate simple, shallow burrows. Within the range of SBKR, this type of substrate is typically associated with alluvial fan sage scrub vegetation (AFSS), now termed scalebroom scrub, a relatively uncommon vegetation type in southern California that develops on alluvial fans and floodplains periodically subjected to scouring and deposition during periodic flood events. The SBKR prefers open habitat characterized by a low stature, relatively open shrub canopy cover (<22 percent cover). Habitats occupied by SBKR also typically exhibit a reduced herbaceous cover with low abundances of European grasses (primarily brome grasses). This type of habitat is typical of early-phase and intermediate-phase alluvial scrub communities, which are subjected to relatively frequent flooding/scouring. The open vegetation structure of these communities supports the highest densities of SBKR. Mature-phase alluvial scrub communities, which typically are located on higher terraces above the more active river channels, are rarely affected by flooding events and subsequently develop a higher density of shrub and non-native grass cover, as well as occasional trees. The SBKR rarely occurs in the mature phase of this vegetation type. However, some confusion has arisen regarding the definition of “mature phase” alluvial scrub; thus, it is necessary to clearly define the conditions prevailing in any alluvial scrub community under study, before its suitability for SBKR can be ascertained. The SBKR is granivorous and known to store quantities of seeds in surface caches similar to other kangaroo rats. Other important food sources include insects and green vegetation. Home ranges confirmed for the nominate subspecies of the Merriam’s kangaroo rat (D. m. merriami) range from approximately 0.8 acres for males to 0.3 acres for females, and it is assumed that the home ranges of the endangered SBKR are similar (USFWS 1998a; McKernan 1997). The SBKR breeding season may extend from January through late November, with peak reproduction occurring in the spring and early summer months. During years of typical rainfall, it is likely that only one litter is produced per year, with an average of only two to three young per litter. Multiple litters undoubtedly are produced during years of higher rainfall, which produce higher vegetative (seed) productivity. The various types of disturbance described above have reduced the historic range of SBKR by 96 percent. In most or all river wash systems presently harboring SBKR these disturbances have negatively affected the species by directly removing habitat and/or by fragmenting remaining occupied habitat patches. In addition, factors that promote higher vegetation cover in alluvial fan scrub communities apparently reduce habitat suitability for the SBKR. Such factors primarily include the construction of levees and dams for flood control or water percolation purposes, which precludes or greatly reduces the frequency of scouring and sand deposition events in vegetation communities away from the primary active river channels. Another species of Heteromyid rodent, the California sensitive (CSC) Los Angeles pocket mouse (Perognathus longimembris brevinasus) (LAPM), also occurs on the Etiwanda Fan in some of the same sandy substrates preferred by SBKR. It typically is found in both very open sandy habitats and dense stands of AFSS and RSS. It is a diminutive granivore whose occupied habitats also have been greatly reduced by development, which has resulted in its being listed as a CSC species. Site Description TT20079 occurs in the southwestern corner of Section 14, Township 1 North, Range 6 West on the Devore USGS 7.5’ quadrangle map. The approximate center of the site occurs at NAD 83 UTM coordinates 11S 455218E/3780626N. A residential development of 21 homes is proposed for the project site, and a contiguous fuel modification area occurs along the northern edge of the proposed subdivision. The property is bordered to the south and east by dense residential housing. To the west is a large dike system topped by a road, which separates the property from the San Sevaine Creek drainage, which is administered by the San Bernardino County Flood Control Department. The top of the dike and road occur many feet above the creek bed to the west, and the dike top road is separated from the creek by a slope comprised of large boulders (rip rap). The project site occurs on moderately sloping terrain immediately southward of the eastern end of the San Gabriel Mountains. Soils on site are classified as Soboba stony loamy sands (Woodruff 1980). More generally, extant soils are sandy but compacted, and deeper deposits of sand typical of those occupied by SBKR are absent. Also, cobble and larger rocks are common components of the soils on site. The property exhibits two large dikes constructed of boulders that are situated in a north-south orientation. Openings, including a few narrow trails, are uncommon on the property (See Figure 4 for a review of features on the property). The property exhibits moderately dense alluvial fan sage scrub (scalebroom scrub) (AFSS) vegetation dominated by the following shrub species: white sage (Salvia apiana), California buckwheat (Eriogonum fasciculatum), scalebroom (Lepidospartum squamatum), California sagebrush (Artemisia californica), poison oak (Toxicodendron diversilobum), and scattered individuals of holly leaf cherry (Prunus ilicifolia). Common herbaceous species include red brome (Bromus madritensis rubens), rip gut brome (B. diandrus), Mediterranean grass (Schismus barbatus), ragweed (Ambrosia sp.), croton (Croton californica), deerweed (Acmispon sp.) (See photographs 1-4). The site occurs on the Etiwanda (Alluvial) Fan, which exhibits an extensive stand of AFSS and Riversidean sage scrub (RSS) vegetation, both of which are considered sensitive habitat types in the Southern California region. The 1203-acre North Etiwanda Preserve (NEP), located nearby to the northwest of the Project Site, has been set aside to preserve a noteworthy stand of these habitat types. SBKR are very unlikely in this Preserve, due to the dense scrub cover and rocky substrates, while Los Angeles pocket mice are generally common. Known Occurrences of SBKR Near TT20079 Records of SBKR captures are very rare in the project area, the nearest records for this species being old and located approximately two miles to the west (McKernan 1997, 1999) and one mile to the south (CNDDB records). However, these localities either are presently developed (southern record) or recent trapping records have not found the species (western record). SBKR records are not known for the immediately adjacent San Sevaine Flood Control wash, and a field visit to portions of this area in 2016-2017 suggested that the species would be an unlikely resident. Habitat conditions observed during this field visit included generally soft sandy-loam soils covered by dense stands of grass, generally rocky soils with very few deeper sandy deposits in the scattered drainage swales in this area, and extremely few locations with the open sandy terraces that are preferred by SBKR. Root (USFWS 2010) found SBKR to be positively correlated with scale-broom presence, and negatively correlated with % cover of annual grass and boulder + cobble. The results of this study tend to support the absence of SBKR in the San Sevaine Wash. In addition, the absence of any SBKR records in or the immediate vicinity of the San Sevaine Wash also provide further suggestion of the species absence. And if SBKR are absent in the San Sevaine Wash, the potential for their occurrence at TT20079 is even lower. TT20079 occurs approximately two miles eastward of an area historically known to have supported low numbers of SBKR (McKernan 1999; USFWS 2017). In addition, the Project Site occurs immediately east and outside of designated Critical Habitat for the SBKR (Figure 5). More specifically, the USFWS designated critical habitat for the SBKR in 2002, and in so doing divided the lands designated as critical habitat into four (4) units. This designation included the Project Site and a larger area surrounding the Project Site as Critical Habitat Unit 4. In 2008, the USFWS revised the critical habitat for this species and removed all the lands within the former Unit 4 from the designation, including the Project Site. A federal court subsequently found that the USFWS had erred in revising the overall critical habitat designation in 2008, and remanded the proposed revisions to the FWS for further action consistent with the court’s opinion. In so doing, the original 2002 critical habitat designation for this species has been effectively reinstated, pending any further revisions of critical habitat for this species by USFWS. The CSC LAPM was captured on lands two miles west of TT20079 during previous trapping surveys conducted by Montgomery (2017, 2014, 2011, 2000). METHODS The Project Site was visited on 11 November 2017 by Stephen J. Montgomery, who is permitted to trap and handle SBKR under authority of a federal (USFWS) permit (TE745541-11) and a Memorandum of Understanding (MOU) with the California Department of Fish and Wildlife (CDFW). During this visit, the Project Site was inspected for habitat conditions typical of those preferred by SBKR, as described above. A search also was conducted for such definite or potential signs of kangaroo rat activity as burrows, scat and dust-bathing sites. Weather during the field visit included clear skies, air temperatures of approximately 75F and wind speeds of 2-7 mph. RESULTS AND DISCUSSION Habitat Conditions Habitat conditions on the property are of very low quality for SBKR. Shrub and grass density are high, and soils are generally gravelly and compacted, with openings in shrub cover being relatively rare. Areas of deep sandy soil typical of occupied SBKR habitat are generally absent throughout. The two dikes on the property create obstacles that would impede movement of SBKR across most of the site. Signs of kangaroo rats were not observed during the field visit. Habitat conditions suitable for the Los Angeles pocket mouse are generally present, and resemble to some degree those on a large recently trapped property to the west where many LAPM were captured (e.g. Montgomery 2017). Surrounding and Nearby Lands Lands surrounding the Project Site are largely or entirely unsuitable for the species and include residential housing to the south and east, and the San Sevaine Creek dike system to the west. Lands directly to the north are like those on TT20079, and are similarly generally unsuitable for SBKR. The previously mentioned recently trapped property to the west, beyond East Etiwanda Creek, yielded numerous LAPM but no SKBR during four trapping efforts between 2000 and 2017, and SBKR were not captured during each field survey. This location encompassed lands where SBKR had been reported by McKernan (1999). The absence of the species at this previously occupied location strongly suggests that SBKR may have been extirpated throughout most (if not all) of this region. Furthermore, habitat conditions at the site that yielded SBKR in the past at this westerly location were superior to those in the San Sevaine Creek wash located immediately west of the current TT20079. SUMMARY No records of SBKR occur in the immediate vicinity of TT20079. Habitat conditions on the site itself are of very low quality for SBKR, the property is surrounded on two sides by dense residential housing, by similar low-quality scrub habitat to the north, and the adjacent dike system (including rip rap edges) to the immediate west that bounds the adjacent San Sevaine Creek wash system would be a major obstacle to movement onto TT20079 by any kangaroo rats that might inhabit the wash. In addition, habitat conditions in the adjacent San Sevaine Creek are sub-optimal for the species. Furthermore, no kangaroo rat sign was observed on TT20079. Even the nearest locality where SBKR was reported in the past by McKernan (1999) appears to lack the species, as indicated by several trapping surveys since 2000 by S.J. Montgomery; and habitat conditions for SBKR in that area are generally superior to those in the San Sevaine Creek wash. These examples of evidence concerning the potential for SBKR occurrence on TT20079 strongly suggest the species is currently absent. Furthermore, the likelihood of any future colonization of the site is low, for the same reasons. In contrast, the LAPM is a potential resident of the property. Please contact me if you have any questions regarding the field survey or this report. Sincerely, Stephen J. Montgomery Permitted San Bernardino Kangaroo Rat Biologist TE745541-11 SJM Biological Consultants, Inc. 2128 North Cobblestone Circle Flagstaff, AZ 86001 (928) 527-1604 FAX (928) 779-4103 Cell (858) 232-9602 steve@sjmbio.com REFERENCES McKernan, R.L., 1997. The Status and Known Distribution of the San Bernardino Kangaroo Rat (Dipodomys merriami parvus): Field surveys conducted between 1987 and 1996. Report prepared for the U.S. Fish and Wildlife Service, Carlsbad Field Office. McKernan, R.L. 1999. Biological Inventory of the Etiwanda Creek Flood Control Project, San Bernardino County. Report prepared for the San Bernardino County Transportation/Flood Control Department, San Bernardino, California. Montgomery, S.J. 2017. Results of a live-trapping survey for the federally endangered San Bernardino Kangaroo rat (Dipodomys merriami parvus) (SBKR) on the approximately 108-acre Tentative Tract 14749 in Rancho Cucamonga, California. Prepared for Tracey Etiwanda Associates, LLC. Riverside, California. Montgomery, S.J. 2014. Results of a live-trapping survey for the federally endangered San Bernardino Kangaroo rat (Dipodomys merriami parvus) (SBKR) on the approximately 108-acre Tentative Tract 14749 in Rancho Cucamonga, California. Prepared for Tracey Etiwanda Associates, LLC. Riverside, California. Montgomery, S.J. 2011. Results of a live-trapping survey for the federally endangered San Bernardino Kangaroo rat (Dipodomys merriami parvus) (SBKR) on the approximately 108-acre Traigh Pacific property in Rancho Cucamonga, California. Prepared for C.A. Page Company, Newport Beach, California. Montgomery, S.J. 2000. Results of a trapping survey for the federally endangered San Bernardino kangaroo rat on the approximately 150-acre Tracy property in Etiwanda, San Bernardino County, California. Prepared for Chambers Group. Irvine, California. Montgomery, S.J. 1998. Results of a site assessment for the federally endangered San Bernardino kangaroo rat on the approximately 100-acre Tracy property in Etiwanda, San Bernardino County, California. Prepared for Chambers Group. Irvine, California. U.S. Fish and Wildlife Service. 2017. Carlsbad Fish and Wildlife Office. GIS Species Occurrence Data. Published 6/29/2017. U.S. Fish and Wildlife Service. 2010. 2005-2009 San Bernardino Kangaroo Rat Survey Analyses from the Woolly Star Preserve Area, San Bernardino County, California. Prepared for U.S. Army Corps of Engineers, Los Angeles District. U.S. Fish and Wildlife Service. 2009. San Bernardino kangaroo rat (Dipodomys merriami parvus) 5-Year Review: Summary and Evaluation. U.S. Fish and Wildlife Service, Carlsbad Field Office. U.S. Fish and Wildlife Service. 1998a. Emergency Rule to list the San Bernardino Kangaroo Rat, San Bernardino and Riverside Counties in Southern California, as Endangered. Federal Register 63(17):3835-3843. U.S. Fish and Wildlife Service. 1998b. Final Rule to list the San Bernardino Kangaroo Rat as Endangered. Federal Register 63(185):51005-51017. U.S. Fish and Wildlife Service, California Department of Fish and Game, San Bernardino Special Districts Department, and North Etiwanda Board of Directors. 2010. DRAFT The North Etiwanda Preserve Management Plan. http://www.specialdistricts.org/2/nep/Documents/DraftManagementPlan-Revision- March18_2010.pdf Woodruff, G. A., 1980. Soil survey of the San Bernardino County, southwestern part, California. U.S. Department of Agriculture, Soil Conservation Service. Figure 1. Regional vicinity map of Tentative Track 20079. Source: Devore USGS 7.5’ Quadrangle Map Figure 2. Site location. Figure 3. Location of project site, adjacent San Sevaine Creek wash and rip-rap dike. I-215 is visible in the southeast corner of the figure. North is to the left. Figure 4. Aerial of the project site showing general habitat conditions, two narrow n-s dikes, surrounding housing, the large San Sevaine Creek dike and wash to the immediate west, and the intervening rip-rap slope. North is to the left. Figure 5. Known occurrences of SBKR and LAPM near TT20079 (Project Area). Specific locations for these species are not shown, in accordance with current CDFW mapping protocol for sensitive animal species. However, the concentric yellow and brown circles indicate that both species are known to occur within these two polygons. Critical Habitat for the SBKR also is shown in cross-hatching. Photographs of Tentative Tract 20079 Photo 1. Bouldery raised dike, near the center of the property looking south, is visible in the right portion of this photograph. Photo 2. General character of scrub habitat on the site - A Photo 3. General character of scrub habitat on the site – B. The large San Sevaine Creek dike is evident in the distance at the top of the photo, looking southwestward from the main n-s dike. Photo 4. Example of typical cobble/rocky soil surface in the few scattered open spots on the property.