Seasonal migration between terrestrial upland habitat and vernal pools, is a critical life history component for the endangered Sonoma County California Tiger Salamander (CTS- Ambystoma californiense). To better understand migratory movements associated with classic clustered vernal pool habitat surrounded by varying land uses, we employed a two-year pitfall trapping study of adult CTS. Pitfall traps and drift fences were installed around four pools on a preserve in Santa Rosa, CA. Using a non-invasive individual identification system, we investigated orientation of individual adult salamanders leaving their breeding pools, influences of surrounding land use on movement, and levels of among-pool movement. We found that individuals moved non-randomly, maintaining a relatively consistent direction toward original entry points when exiting. Furthermore, the direction between entry and exits was significantly affected by surrounding land use; individual entries associated with rural residences tended to stray further, relative to entries associated with preserve and cattle grazed preserve. Within a breeding season, only a small proportion of individuals visited a second pool; however, by far, most individuals visited only one pool despite the high density of clustered pools available.

Several aquatic sampling techniques are commonly used to detect and quantify amphibian larvae. Although many techniques have been standardized, comparisons among methods have been poorly studied. We employed a removal design to investigate the detection rate of amphibian larvae using box enclosures and evaluated the reliability of timed dipnet sampling relative to the more quantitative box enclosure sampling across 13 vernal pools. For these comparisons, we studied larvae of the endangered California Tiger Salamander (Ambystoma californiense; CTS) and the smaller and more abundant tadpoles of the Pacific Treefrog (Pseudacris regilla; PTF). Based on N-mixture model estimates, box enclosure sampling captured only 5% more of the CTS larvae present than PTF tadpoles, despite disparities in their sizes and estimated abundances. Dipnet sampling was slightly more effective at detecting CTS larvae than enclosure sampling, while both methods equally detected PTF tadpoles. We found a strong relationship (R2 = 0.92) between the densities of CTS larvae estimated from dipnet sampling and those calculated from the more quantitative enclosure sampling, indicating that dipnet sampling is a reliable measurement of relative abundance. We conclude that timed dipnet surveys can be an important tool for monitoring populations of CTS, and possibly other lentic-breeding amphibians, especially given its relative efficiency that can be replicated across both time and space.

The federally and state threatened California tiger salamander (CTS; Ambystoma californiense) is a large salamander endemic to the San Joaquin-Sacramento River and coastal valleys of Central California. CTS require access to both aquatic and upland habitat throughout their life cycle. The upland habitat must contain subterranean refugia typically in the form of animal burrows [i.e., California ground squirrel (Spermophilus beecheyi) or valley pocket gopher (Thommomys bottae)] for foraging and shelter from predators and desiccation during nonbreeding periods. Take avoidance measures are required by state and/or federal agencies prior to the start of development projects that have the potential to impact upland habitat include amongst other measures: burrow excavation. Burrow excavation is costly, laborious, and requires extensive experience to perform. Excavation of burrows also includes a variety of inherent hazards to surveyors including exposure to the fungus coccidioidomycosis (i.e., Valley fever). In this presentation we will discuss a case study involving a multiyear burrow excavation dataset collected between 2018-2021 from a project involving a greenfield industrial development in the San Joaquin Valley.

The northwestern pond turtle (Actinemys marmorata; WPT hereafter) is a semi-aquatic freshwater turtle native to the west coast of North America and is experiencing significant population decline. Identifying predators of WPT females and their eggs can address major gaps in data regarding western pond turtle mortality and population-limiting factors. During the WPT nesting season in 2021, we documented nest predation events by examining trace predator DNA (i.e., saliva) collected from WPT eggshell, carapace, or plastron fragments found at predated nest sites located in Humboldt County, California. We also developed a field protocol to collect WPT eggshell and carapace or plastron fragments that would limit the possibility of contamination. To examine the evidence of potential predators, we conducted forensic molecular analyses and developed a polymerase chain reaction (PCR) protocol to detect mammal species, which focused on amplifying carnivore DNA using carnivore-specific primers. Our results successfully identified the western spotted skunk (Spilogale gracilis) as a local mammalian predator of WPT nests. Our study outlines field and laboratory techniques and methods useful for obtaining and amplifying trace DNA exposed to environmental elements, as well as a deeper investigation into declining WPT populations.

After a decadal long drought and the recent Tenaja Fire at the Santa Rosa Plateau Ecological Reserve in Riverside County, CA, a southwestern pond turtle population was sampled and demography assessed in Spring 2023. The population experienced a change from previous data, where turtle growth was stunted and the sex ratio shifted to a male bias sex ratio. The changes in population demography indicate that these stochastic events are causing a disruption in population stability and may have long term effects. There is a need to further investigate and monitor this population to better understand the long term effects these events will have on this turtle population.

The Western Pond Turtle (Actinemys marmorata, WPT) – a native freshwater turtle in California – is a species of special concern, as determined by the California Department of Fish and Wildlife and is currently under review to be listed as threatened by the Fish and Wildlife Service. In the Suisun Marsh, WPT are thought to be widespread based on observational data; however, little is known about their population status and habitat requirements in this part of their range. Suisun Marsh consists of a mosaic of tidal and managed brackish water wetlands, with 5,000–7,000 acres of tidal restoration planned by 2043. As changes like tidal restoration and predicted sea level rise occur, it will be increasingly important to understand how freshwater species like WPT respond. In this study, WPT were tracked before and after a restoration project at the Hill Slough Wildlife Area within Suisun Marsh using GPS/GSM trackers. On average home ranges increased after restoration, and in some cases WPT shifted the center of their home ranges by up to 1,500 meters. Lessons learned from this study can help inform adaptive management and provide guidelines for future restoration, aiding managers in efforts to conserve WPT in the future.