San Diego Management & Monitoring Program


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2009 Impacts of Urbanization on the Western Pond Turtle in Southern California book/conf proceeding

Lead author: Sara L. Schuster

2020 Historical museum collections and contemporary population studies implicate roads and introduced predatory bullfrogs in the decline of western pond turtles journal article

Lead author: E. Griffin Nicholson
The western pond turtle (WPT), recently separated into two paripatrically distributed species (Emys pallida and Emys marmorata), is experiencing significant reductions in its range and population size. In addition to habitat loss, two potential causes of decline are female-biased road mortality and high juvenile mortality from non-native predatory bullfrogs (Rana catesbeiana). However, quantitative analyses of these threats have never been conducted for either species of WPT. We used a combination of historical museum samples and published and unpublished field studies shared with us through personal communications with WPT field researchers (B. Shaffer, P. Scott, R. Fisher, C. Brown, R. Dagit, L. Patterson, T. Engstrom, 2019, personal communications) to quantify the effect of roads and bullfrogs on WPT populations along the west coast of the United States. Both species of WPT shift toward increasingly male biased museum collections over the last century, a trend consistent with increasing, female-biased road mortality. Recent WPT population studies revealed that road density and proximity were significantly associated with increasingly male-biased sex ratios, further suggesting female-biased road mortality. The mean body size of museum collections of E. marmorata, but not E. pallida, has increased over the last 100 years, consistent with reduced recruitment and aging populations that could be driven by invasive predators. Contemporary WPT population sites that co-occur with bullfrogs had significantly greater average body sizes than population sites without bullfrogs, suggesting strong bullfrog predation on small WPT hatchlings and juveniles. Overall, our findings indicate that both species of WPT face demographic challenges which would have been difficult to document without the use of both historical data from natural history collections and contemporary demographic field data. Although correlational, our analyses suggest that female-biased road mortality and predation on small turtles by non-native bullfrogs are occurring, and that conservation strategies reducing both may be important for WPT recovery.

2003 Who let the turtles out? other

Lead author: Robert N. Fisher
Rapid urbanization has led to the loss and degradation of riparian habitats in Southern California. In response to the need to protect and manage habitat for native species in the South Coast Eco-Region of Southern California, the Natural Communities Conservation Planning Program (NCCP) was initiated in 1991 as a way for California Department of Fish and Game and US Fish and Wildlife Service to jointly implement habitat conservation plans (HCP). The western pond turtle (Clemmys marmorata) is a covered species in the San Diego Multiple Species Conservation Program subarea (MSCP). However, the current status and distribution of the western pond turtle within the MSCP is poorly known. The western pond turtle is the only turtle native to southwestern California and was historically abundant in most major drainages in San Diego. Surveys conducted in Southern California in the late 1980's suggested that pond turtles no longer occurred in many locations from which they were known historically and that few viable populations of turtles remained. The United States Geological Survey began conducting surveys for western pond turtles in the San Diego MSCP in 2002. During these surveys, non-native turtles were detected at many more locations than were western pond turtles. Western pond turtles co-occur with non-native turtles at least one of these locations. Surveys will continue during spring and summer 2003.

2006 USGS Western Pond Turtle (Emys marmorata) Visual Survey Protocol for the Southcoast Ecoregion other

This protocol documents standard visual survey techniques for southern populations of the western pond turtle (Emys marmorata), hereafter referred to as pond turtle, in the southcoast ecoregion of the United States (within the U. S. this extends from Santa Barbara, California to the Mexican boarder). The purpose of this protocol is to provide standard guidelines for determining pond turtle presence and relative abundance. The protocol also contributes information on general habitat components and disturbances found at each location so that hypotheses can be formulated and tested as to why a species occurs or does not occur in a particular area. In addition, the techniques are effective at documenting other aquatic species such as fish, amphibians, snakes, and other aquatic freshwater taxa. This protocol is based on methods found in the USGS Aquatic Species and Habitat Assessment Protocol for Southcoast Ecoregion Rivers, Streams, and Creeks (U. S. Geological Survey, 2006a).

2004 Distribution and Status of the Western Pond Turtle (Emys marmorata) in the San Diego MSCP and Surrounding Areas, 2002-2003 other


2009 Impacts of habitat loss, fragmentation, and the introduction of non-native species as a result of urbanization on the western pond turtle in southern California. other

Lead author: Robert N. Fisher
More than 90% of southern California's riparian and aquatic habitats have been destroyed or modified by agriculture and urbanization. This has had profound effects on species dependant on these habitats including the western pond turtle, Actinemys marmorata, the only freshwater aquatic turtle native to southern California. We have been monitoring the southern California pond turtle populations since 2001 and have documented their decline. This decline is a result of the direct and indirect effects of urbanization including habitat loss, habitat alteration, habitat fragmentation, the introduction of non-native species, and recreation activities. Our trap efforts have detected a minimum of 15 species of non-native turtles in southern California with red-eared sliders and spiny softshell the most common. At sites occupied by non-native turtles, non-native turtles outnumber the native turtles. We have also documented a negative correlation between pond turtle presence and sites with recreational use, while non-native turtles are positively correlated with recreational use. Finally pond turtle presence is positively correlated with the naturalness of a site while non-natives were more likely to occur at modified or artificial sites. Only a few viable pond turtle populations remain in southern California, most populations are male-biased with little to no recruitment. Currently, we are developing programs such as long-term monitoring, genetics microsatellite analysis, habitat suitability assessment, habitat restoration and creation, translocation, head starting, and captive breeding to be used as tools to promote the recovery of self-sustaining populations of the pond turtles in southern California.

2006 USGS Western Pond Turtle (Emys marmorata) Trapping Survey Protocol for the Southcoast Ecoregion other

This protocol documents standard trapping survey techniques for southern populations of the western pond turtle (Emys marmorata), hereafter referred to as pond turtle, in the southcoast ecoregion of the United States (within the U. S. this extends from Santa Barbara, California to the Mexican boarder). The purpose of this protocol is to provide standard guidelines for determining pond turtle presence, relative abundance, population demographics and provide baseline information applicable to declines in pond turtle populations. The protocol, in combination with the USGS Western Pond Turtle (Emys marmorata) Visual Survey Protocol for the Southcoast Ecoregion, contributes information on general habitat components and disturbances found at each location so that hypotheses can be formulated and tested as to why a species occurs or does not occur in a particular area (U. S. Geological Survey, 2006a). In addition, the techniques are effective at documenting other aquatic species such as fish, amphibians, and other aquatic freshwater taxa. This protocol is based on methods found in the USGS Aquatic Species and Habitat Assessment Protocol for Southcoast Ecoregion Rivers, Streams, and Creeks (U. S. Geological Survey, 2006b).

2014 Southwestern Pond Turtle: Connectivity Strategic Plan for Western San Diego County powerpoint presentation

Lead author: Chris Brown
Presentation for the Connectivity Strategic Plan for Western San Diego County Science Session – July 1, 2014

2015 Status and Management of the Pacific Pond Turtle in San Diego County with Consideration of Road Effects powerpoint presentation

Lead author: Chris Brown

2018 014_CBrown_SensitiveResources powerpoint presentation

Lead author: Chris Brown

2020 Research for Restoration and Recovery of a Protected Species: Results of Management Actions for the Southern Western Pond Turtle (Emys pallida) in San Diego powerpoint presentation

Lead author: Chris Brown

2018 Western Pond Turtle Status and Management in San Diego County powerpoint presentation

Lead author: Chris Brown

2003 Western Pond Turtles (Clemmys marmorata) in the Multiple Species Conservation Program Area powerpoint presentation

Lead author: Kathie Meyer
Preliminary Survey Results 2002

2009 USGS Riparian Herpetofaunal Studies in Coastal San Diego, CA powerpoint presentation

Lead author: Chris Brown
Powerpoint presentation on pond turtle and arroyo toad surveys across MSCP study area.

2018 Status and Management in San Diego County powerpoint presentation

Lead author: Chris Brown

2004 The Western Pond Turtle (Emys marmorata) in the San Diego MSCP and Surrounding Areas powerpoint presentation

Lead author: Melanie Madden-Smith
Determine the current distribution and population status of the western pond turtle in the San Diego MSCP and surrounding areas. Determine wetland and upland habitat value. Provide management recommendations for the San Diego MSCP.

2012 Data Summary for the TransNet Environmental Mitigation Program Grant Agreement 5001140 Regarding Southwestern Pond Turtle Restoration at Sycuan Peak Ecological Reserve, March 2012 report

Lead author: Chris Brown

2011 Progress Report and Preliminary Results for the TransNet Environmental Mitigation Program Southwestern Pond Turtle Restoration at Sycuan Peak Ecological Reserve, August 2011 report


2012 Data Summary for the TransNet Environmental Mitigation Program Grant Agreement 5001140 Regarding Southwestern Pond Turtle Restoration at Sycuan Peak Ecological Reserve, March 2012 report

Lead author: Chris Brown

2008 Western Pond Turtle Surveys and Habitat Restoration Plan (#P0650002) report


2003 Arroyo Toad and Western Pond Turtle in the San Diego Multiple Species Conservation Program Area, 2002 report

Lead author: Kathie Meyer
Rapid urbanization has led to the loss and degradation of riparian habitats in southern California. In response to the need to protect and manage habitat for native species in the South Coast Eco-Region of Southern California, the Natural Communities Conservation Planning Program (NCCP) was initiated in 1991. The arroyo toad (Bufo californicus) and western pond turtle (Clemmys marmorata) are covered species in the San Diego Multiple Species Conservation Program (MSCP). However, the current status and distribution of the arroyo toad and the western pond turtle within the MSCP is poorly known. Direct habitat loss in conjunction with hydrological alterations and the introduction of nonnative species have caused arroyo toads to disappear from about 75% of previously occupied habitat within the United States. The western pond turtle is the only turtle native to southwestern California and was historically abundant in most major drainages in San Diego County. Surveys conducted in southern California in the late 1980's suggested that pond turtles no longer occurred in many historic locations and that few viable populations of turtles remained. The US Geological Survey conducted surveys for the arroyo toad and western pond turtle at select sites within the San Diego MSCP in 2002. Arroyo toads were observed at two of the 7 sites surveyed and western pond turtles were detected at 3 of the 26 sites surveyed. A suite of non-native aquatic predatory species known to have deleterious effects on native amphibian species was detected at 46% of the sites that contained surface water during the surveys. Non-native turtles were detected at more locations than western pond turtles. Western pond turtles co-occur with nonnative turtles at least at one location. Surveys for both, arroyo toads and western pond turtles will continue during spring and summer 2003.

2005 Distribution and Status of the Arroyo Toad (Bufo californicus) and Western Pond Turtle (Emys marmorata) in the San Diego MSCP and Surrounding Areas Final Report 10/11/05 report

Lead author: Melanie Madden-Smith
Rapid urbanization has led to the loss and degradation of riparian habitats within the Southern California Coastal Sage Scrub Region. In response to the need to protect and manage riparian and other sensitive habitats in southern California, the Natural Communities Conservation Planning (NCCP) Act was enacted in 1992. The San Diego County subregional plan under the NCCP is the San Diego County Multiple Species Conservation Program (MSCP). The MSCP has been designated to protect such sensitive species as the arroyo toad (Bufo californicus) and western pond turtle (Emys marmorata) within its boundaries by preserving lands with known populations, controlling non-native species, minimizing human impacts, and restoring or enhancing native habitats. Direct habitat loss in conjunction with hydrological alterations and the introduction of non-native species has caused the arroyo toad to disappear from about 75% of previously occupied habitat (Jennings & Hayes 1994) and has resulted in a decrease in the number of viable populations of the western pond turtle in southern California (Brattstrom & Messer 1988; Jennings et al. 1992; Jennings & Hayes 1994). Prior to this study, little was known about the current status and distribution of the arroyo toad and the western pond turtle within the San Diego MSCP lands. In 2002 and 2003 the U. S. Geological Survey conducted focused surveys for the arroyo toad and western pond turtle within nine watersheds of San Diego County, eight of which fall within the MSCP boundaries. Daytime arroyo toad habitat surveys were conducted at 39 sites. Eighteen of these sites were determined to have potential for supporting arroyo toads because of the presence of suitable habitat and/or the close proximity of historical locality record(s) and were surveyed nocturnally for the presence of arroyo toads. Arroyo toads were located at five sites, all but one were previously known locations and all were within the MSCP boundaries. Visual and/or trapping surveys were conducted for western pond turtles at 68 sites for a total of 67 visual and 45 trapping surveys. Western pond turtles were detected at nine sites, six of which are within the MSCP boundaries, and all locations but one were previously known. Population sizes of both species appear to be small. Although mark-recapture data were not collected for arroyo toads and it is not possible to make population estimates, 18 was the largest number of arroyo toads detected at a site during the course

2015 Western Pond Turtle (Emys marmorata) Restoration and Enhancement in San Diego County, CA, 2013-2015 report

Lead author: Chris Brown

2015 Western Pond Turtle (Emys marmorata) Restoration and Enhancement in San Diego County, CA, 2013-2015 report

Lead author: Chris Brown

2008 Data Summary for the 2007 and 2008 Pacific Pond Turtle (Actinemys marmorata) Surveys Conducted in the County of San Diego; Boulder Oaks, Lusardi Creek and Los Penasquitos Canyon report

Lead author: Chris Brown
The Pacific pond turtle (Actinemys marmorata) is the only native aquatic turtle species in southwestern California. While historically abundant in most major San Diego County drainages: habitat loss, human disturbance, hydrologic alterations, and invasive species have resulted in a significant decrease in Pacific pond turtle populations in San Diego and throughout California (Madden-Smith et al. 2005). Evaluating and addressing these threats is critical for the long-term persistence of Pacific pond turtle populations in San Diego County, and is a focus of the Multiple Species Conservation Program (MSCP), an approved Natural Community Conservation Plan (NCCP) in southern San Diego County. The Pacific pond turtle is a MSCP covered species with an impact avoidance condition. The condition is as follows: "Maintain and manage areas within 1500 feet around known locations within preserve lands for the species. Within this impact avoidance area, human impacts will be minimized, non-native species detrimental to pond turtles will be controlled, and habitat restoration/enhancement measures will be implemented." During a 2002-2003 study conducted by the United States Geological Survey (USGS), 72 sites within the MSCP area were surveyed for Pacific pond turtle presence. Pacific pond turtles were detected at only 5 of these 72 sites (Lake Murray, Los Penasquitos Canyon Preserve, Lusardi Creek Preserve Lands, Santee Lakes, and Sycuan Peak Ecological Reserve), only 3 of which had more than one individual (Los Penasquitos Canyon Preserve, Lusardi Creek Preserve Lands, and Sycuan Peak Ecological Reserve along the Sweetwater River; Madden-Smith et al. 2005). The surveys conducted by the USGS in 2002-2003, provided valuable information regarding the distribution of Pacific pond turtles, and raised management concerns about their viability. Following the 2002-2003 survey efforts, MSCP managers have sought to assess additional unsurveyed sites, and to prioritize and implement restoration actions to ensure the persistence of western pond turtles within the MSCP Preserve System. The Boulder Oaks Preserve became a part of the MSCP preserve system in 2003 after completion of the 2002-2003 USGS survey and has not been surveyed for Pacific pond turtles. Boulder Oaks Preserve includes three ponds which are potential habitat for Pacific pond turtles. Unlike other sites where restoration actions may be affected by human impacts (e.g., invasive species i

2004 Habitat Assessment and Baseline Surveys for the Western Spadefoot (Spea hammondii) and the Western Pond Turtle (Emys marmorata) on the Irvine Ranch Land Reserve report

Lead author: Robert N. Fisher
Recent conservation planning for Orange County identifies the western spadefoot (Spea hammondii) and western pond turtle (Emys marmorata) as species requiring protection (NCCP/HCP, 1995). The western spadefoot is listed as a federal species of concern, a California Department of Fish and Game (CDFG) species of special concern, Bureau of Land Management (BLM) sensitive species and Natural Community Conservation Plan (NCCP) County of Orange target species. The western pond turtle is listed as a federal species of concern, a CDFG species of special concern, a BLM sensitive species, and a United States Forest Service sensitive species. Initial surveys of Irvine Ranch lands for the western spadefoot (coastal reserve only) and the western pond turtle were conducted in 1995 and 1997, respectively. The United States Geological Survey (USGS) conducted surveys in 2003 and 2004 to 1) identify currently occupied habitats and 2) assess population status for these two locally rare species within the Irvine Ranch Land Reserve (IRLR). USGS surveys encompassed portions of both the IRLR coastal and central reserves. Western spadefoots were found to be widespread in the central reserve, occurring in all six surveyed areas. In the coastal reserve, western spadefoots were detected in two of the six surveyed areas. Western pond turtles were detected at 4 of the 32 surveyed area on Irvine Ranch lands, all west of Interstate 5. Western pond turtles were detected at the University of California, Irvine's (UCI's) San Joaquin Freshwater Marsh and adjacent portions of the San Diego Creek Channel. At two sites, Bonita Canyon and Strawberry Farms Golf Course only a single western pond turtle was detected. Currently the largest populations of western pond turtles within the IRLR are at the Shady Canyon turtle pond mitigation site. The success of The Irvine Company's (TIC) mitigation effort at the Shady Canyon turtle pond indicates successful turtle habitats can be created and maintained. This report summarizes USGS's habitat assessment of the baseline surveys of both the western spadefoot and western pond turtle on Irvine Ranch Land Reserve, and provides recommendations for management to conserve these species within the IRLR.

2010 Notes from Southwestern Pond Turtle Meeting on 1 November 2010 workshop summary

Lead author: Tim Hovey
Southwestern pond turtle (WPT) has been identified as a focal species for management in the draft Fiscal Year 2011 Land Management Grant Program. The San Diego Management and Monitoring Program is trying to assemble information regarding potential management actions to improve the status of WPT populations in San Diego County.