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Synergistic effects of habitat loss, drought, and climate change exacerbate amphibian declines. In southern California urbanization continues to convert natural habitat, while prolonged drought reduces surface water availability. Protection of biodiversity may be provided through mitigation; however, the long-term effectiveness of different strategies is often unreported. As a mitigation measure for building a new development within occupied Spea hammondii (western spadefoot) habitat in Orange County, California, artificial breeding pools were constructed at two off-site locations. Spea hammondii tadpoles were translocated from the pools at the development site to two off-site locations in 2005–2006. We conducted surveys a decade later (2016) to determine if S. hammondii were persisting and breeding successfully at either the original development site or the human-made pools at the two mitigation sites. We also verified hydroperiods of any existing pools at all three locations to see if any held water long enough for successful S. hammondii recruitment through metamorphosis. During our study, no pooling water was detected at two of three main sites surveyed, and no S. hammondii were observed at these locations. Twelve of the 14 pools created at only one of the two mitigation sites held water for over 30 d, and we detected successful breeding at seven of these pools. Recruitment in some mitigation ponds indicated that S. hammondii habitat can be created and maintained over 10+ yr, even during the fifth year of a catastrophic drought. Therefore, this may also serve as a conservation strategy to mitigate climate change and habitat loss

Extensive urbanization in coastal southern California has reduced natural habitat in this biodiversity hotspot. To better conserve ecological communities, state and federal agencies, along with local jurisdictions and private stakeholders, developed regional conservation plans for southern California. Although many protected areas exist within this region, the patchwork nature of these protected areas might not provide good coverage for species that require multiple habitat components, such as amphibians with complex life histories. Because of declines in the past century, the status of the western spadefoot (Spea hammondii) in southern California is of concern to state and federal wildlife agencies. Species distribution models (SDMs) can aid in determining the conservation status of imperiled species by projecting where suitable habitat remains and how much is protected from further development. We built SDMs that integrated site-occupancy data from systematic pitfall trapping surveys and presence-only data from biodiversity databases and citizen science platforms to project the current distribution of western spadefoots in southern California. Western spadefoot occurrence was positively related to the cover of grassland or shrub/scrub and the % sand in the soil within a 1000 m buffer, and was negatively related to slope, elevation, and distance to ephemeral streams or vernal pools. Most of the remaining unprotected habitat for western spadefoots is in the southern half of its historical range in western San Diego and Riverside counties. A few large tracts of spadefoot habitat exist on U.S. Department of Defense lands and smaller tracts remain on ecological reserves owned by state and local government agencies. Only small patches of habitat remain in the northern half of this clade’s historical range in Ventura, Orange, Los Angeles, and San Bernardino counties. Existing regional conservation plans provide ostensible spatial coverage of the majority of extant habitat for western spadefoots in southern California, but most of the habitat within the jurisdiction of these plans lacks formal protection, exposing this species to further declines as urbanization continues in the 21st century.

Conservation of species reliant on ephemeral resources can be especially challenging in the face of a changing climate. Western spadefoots (Spea hammondii) are small burrowing anurans that breed in ephemeral pools, but adults spend the majority of their lives underground in adjacent terrestrial habitat. Western spadefoots are of conservation concern throughout their range because of habitat loss, but little is known about the activity patterns and ecology of their terrestrial life stage. We conducted a radio‐telemetry study of adult western spadefoots at 2 sites in southern California, USA, from December 2018 to November 2019 to characterize their survival, behavior, and movements from breeding through aestivation to refine conservation and management for the species. Western spadefoot survival varied seasonally, with risk of mortality higher in the active season than during aestivation. The probability of movement between successive observations was higher during the winter and spring and when atmospheric moisture was high and soil water content at 10‐cm depth was low. The amount of rain between observations had the strongest effect on the probability of movement between observations; for every 20mm of rainfall between observations, western spadefoots were 2.4 times more likely to move. When movements occurred, movement rates were highest when both relative humidity and soil water content at 10‐cm depth were high. The conditions under which western spadefoots were likely active on the surface, likely to have moved, and moved at the highest rates are conditions that reduce the risk of desiccation of surface‐active spadefoots. Western spadefoot home range areas varied between study sites and were mostly <1 ha, although 1 individual's home range area was >6ha. Western spadefoots rapidly dispersed from the breeding pools, and asymptotic distances from the breeding pool were generally reached by June. The asymptotic distance from the breeding pool varied between sites, with the 95th percentile of the posterior predictive distribution reaching 486m at 1 site and 187m at the other. Western spadefoots did not select most habitat components disproportionately to their availability, but at Crystal Cove State Park, they avoided most evaluated vegetation types (graminoids, forbs, and shrubs). Spatial variation was evident in most evaluated western spadefoot behaviors; context‐dependent behavior suggests that site‐specific mana

The western spadefoot (Spea hammondii, spadefoot) is under review for federal listing by the U.S. Fish and Wildlife Service (ECOS January 2023) and is a California Department of Fish and Wildlife (CDFW) Species of Special Concern (CNDDB 2023). The species is also a covered species in the County of Orange Central and Coastal Subregions Natural Community Conservation Plan (NCCP/HCP 1995). In southern California more than 80% of spadefoot habitat has been lost to development (Jennings and Hayes 1994) and suitable habitat in northern California has been significantly reduced (Fisher and Shaffer 1996; Rose et al. 2020). Spadefoot are small, nocturnal, burrowing anurans. The adults spend most of their lives burrowed in terrestrial habitat, emerging primarily during rain events to feed and breed. Spadefoot historically breed in vernal pools but are known to take advantage of any seasonal water body, such as road ruts, cattle ponds and created pools due to diminishing and limited vernal pool habitat (Stebbins and McGinnis 2012). Pools must persist for a minimum of 30 days for their larvae to complete development (Morey and Reznick 2004).

The western spadefoot (Spea hammondii, spadefoot) is under review for federal listing by the U.S. Fish and Wildlife Service (ECOS March 2020) and is a California Department of Fish and Wildlife (CDFW) Species of Special Concern (CDFW 2019). The species is also a covered species in the County of Orange Central and Coastal Subregions Natural Community Conservation Plan (NCCP/HCP 1995). In southern California more than 80% of spadefoot habitat has been lost to development (Jennings and Hayes 1994) and suitable habitat in northern California has been significantly reduced (Fisher and Shaffer 1996; Rose et al. 2020). Spadefoot are small, nocturnal, burrowing anurans. The adults spend the majority of their lives burrowed in terrestrial habitat, emerging primarily during rain events to feed and breed. Spadefoot historically breed in vernal pools but are known to take advantage of any seasonal water body, such as road ruts, cattle ponds and created pools due to diminishing and limited vernal pool habitat (Stebbins and McGinnis 2012). Pools must persist for a minimum of 30 days for their larvae to complete development (Morey and Reznick 2004). This study was conducted to provide the U.S. Fish and Wildlife Service with a current assessment of occupied habitat across California. In southern California these surveys will also be used for a future model of habitat suitability for the species by comparing occupancy of current aquatic breeding sites to formerly documented breeding sites and occurrences recorded during USGS surveys conducted in the early 2000s.

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.

The updated inventory provides current and expanded information regarding the location of vernal pool basins and rare, threatened, and endangered biota within the City of San Diego. The resulting data, which includes vernal pools on private and public lands, will be analyzed to determine the extent of vernal pool protection, as well as current preservation and management needs. This new information will serve as the basis for updating the City of San Diego Vernal Pool Management Plan (1996), which identifies and prioritizes management activities for vernal pools on land owned by the City of San Diego.