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Papers & Reports The influence of species life history and distribution characteristics on species responses to habitat fragmentation in an urban landscape
Authors: Staci M Amburgey; David AW Miller; Carlton J Rochester; Katy S Delaney; Seth PD Riley; Cheryl S Brehme; Stacie A Hathaway; Robert N Fisher
Date: 2021-01-20 | Outlet: Journal of Animal Ecology
1. Fragmentation within urbanized environments often leads to a loss of native species diversity; however, variation exists in responses among-species and among-populations within species.
2. We aimed to identify patterns in species biogeography in an urbanized landscape to understand anthropogenic effects on vertebrate communities and identify species that are more sensitive or resilient to landscape change.
3. We investigated patterns in species richness and species responses to fragmentation in southern Californian small vertebrate communities using multispecies occupancy models and determined factors associated with overall commonness and sensitivity to patch size for 45 small vertebrate species both among and within remaining non-developed patches.
4. In general, smaller patches had fewer species, with amphibian species richness being particularly sensitive to patch size effects. Mammals were generally more common, occurring both in a greater proportion of patches and a higher proportion of the sites within occupied patches. Alternatively, amphibians were generally restricted to larger patches but were more ubiquitous within smaller patches when occupied. Species range size was positively correlated with how common a species was across and within patches, even when controlling for only patches that fell within a species’ range. We found sensitivity to patch size was greater for more fecund species and depended on where the patch occurred within a species’ range. While all taxa were more likely to occur in patches in the warmer portions of their ranges, amphibians and mammals were more sensitive to fragmentation in these warmer areas as compared to the rest of their ranges. Similarly, amphibians occurred at a smaller proportion of sites within patches in drier portions of their ranges. Mammals occurred at a higher proportion of sites that were also in drier portions of their range while reptiles did not differ in their sensitivity to patch size by range position.
5. We demonstrate that taxonomy, life history, range size, and range position can predict commonness and sensitivity of species across this highly fragmented yet biodiverse landscape. The impacts of fragmentation on species communities within an urban landscape depend on scale, with differences emerging among and within species and populations.
2. We aimed to identify patterns in species biogeography in an urbanized landscape to understand anthropogenic effects on vertebrate communities and identify species that are more sensitive or resilient to landscape change.
3. We investigated patterns in species richness and species responses to fragmentation in southern Californian small vertebrate communities using multispecies occupancy models and determined factors associated with overall commonness and sensitivity to patch size for 45 small vertebrate species both among and within remaining non-developed patches.
4. In general, smaller patches had fewer species, with amphibian species richness being particularly sensitive to patch size effects. Mammals were generally more common, occurring both in a greater proportion of patches and a higher proportion of the sites within occupied patches. Alternatively, amphibians were generally restricted to larger patches but were more ubiquitous within smaller patches when occupied. Species range size was positively correlated with how common a species was across and within patches, even when controlling for only patches that fell within a species’ range. We found sensitivity to patch size was greater for more fecund species and depended on where the patch occurred within a species’ range. While all taxa were more likely to occur in patches in the warmer portions of their ranges, amphibians and mammals were more sensitive to fragmentation in these warmer areas as compared to the rest of their ranges. Similarly, amphibians occurred at a smaller proportion of sites within patches in drier portions of their ranges. Mammals occurred at a higher proportion of sites that were also in drier portions of their range while reptiles did not differ in their sensitivity to patch size by range position.
5. We demonstrate that taxonomy, life history, range size, and range position can predict commonness and sensitivity of species across this highly fragmented yet biodiverse landscape. The impacts of fragmentation on species communities within an urban landscape depend on scale, with differences emerging among and within species and populations.
Papers & Reports The Coyote Mountains’ Desert Snail (Sonorelix harperi carrizoensis), a Lazarus Species with the First Documentation of Live Individuals
Authors: Robert N Fisher; S R Fisher
Date: 2020-08 | Outlet: Bulletin Southern California Academy of Sciences 119:49-54.
The Coyote Mountain desert snail (Sonorelix harperi carrizoensis) was described in 1937 from 30 dry shells collected the previous year. We reviewed the literature and museum records and found two additional shell collections for this subspecies from the type locality one from 1958, and one from an adjacent mountain range in 1938. There is no evidence previously of any live snails being collected from the Coyote Mountains, Imperial County, California. All shell collections of S. harperi carrizoensis have the same locality data as the type series, which is Painted Gorge, Coyote Mountains except for one recorded collection of shells from the Vallecito Mountains from 1938. Using geological maps and other data sources, a potential mesic habitat was identified in the Coyote Mountains. During recent field work for salamanders at this location we detected two live specimens of S. harperi carrizoensis approximately 2 km north of its type location. This new data confirms this subspecies is still extant and has occurred at least at two sites historically in these mountains. Despite the presence of mesic habitats (i.e., mosses, liverworts and ferns) at the type locality, we found no evidence of S. harperi carrizoensis or salamanders.
News & Stories Urban Southern California is a Center of Diversification for Salamander Lineages
Authors: Robert N Fisher
August 15, 2020
The Southern California Biodiversity Hotspot has a complex geological history and has a human population of about 24 million people. A recent study of genetic diversity across salamanders that occur here found high levels of localized diversity representing ancient mitochondrial lineages. Several of these lineages are very geographically limited and occur only within this urban matrix. Each of the three National Parks (Channel Islands National Park, Santa Monica Mountains National Recreational Area, and Cabrillo National Monument) in this southern California landscape will be important for the long term persistence of unique lineages that are almost micro-endemics to just these park units. Various Bureau of Land Management lands in this regional also house highly divergent lineages that could serve as conservation targets. Lastly, this work provides further support for the importance of the continued US Fish and Wildlife program of Habitat Conservation Planning within this Biodiversity Hotspot for conserving undescribed ancient patterns of genetic diversity.
Papers & Reports Slender salamanders (genus Batrachoseps) reveal Southern California to be a center for the diversification, persistence, and introduction of salamander lineages
Authors: E Jockusch; R Hansen; Robert N Fisher; D B Wake
Date: 2020-08-14 | Outlet: PeerJ 8:e9599
Background. The southern California biodiversity hotspot has had a complex geological history, with both plate tectonic forces and sea level changes repeatedly reconfiguring the region, and likely driving both lineage splittings and extinctions. Here we investigate patterns of genetic divergence in two species of slender salamanders (Plethodontidae: Batrachoseps) in this region. The complex geological history in combination with several organismal traits led us to predict that these species harbor multiple ancient mitochondrial lineages endemic to southern California. These species belong to a clade characterized by fine-scale mitochondrial structure, which has been shown to track ancient splits. Both focal species, Batrachoseps major and B. nigriventris, are relatively widely distributed in southern California, and estimated to have persisted there across millions of years. Recently several extralimital populations of Batrachoseps were found in the San Joaquin Valley of California, a former desert area that has been extensively modified for agriculture. The origins of these populations are unknown, but based on morphology, they are hypothesized to result from human-mediated introductions of B. major.
Methods. We sequenced the mitochondrial gene cytochrome b from a geographically comprehensive sampling of the mitochondrial lineages of B. major and B. nigriventris that are endemic to southern California. We used phylogenetic analyses to characterize phylogeographic structure and identify mitochondrial contact zones. We also included the San Joaquin Valley samples to test whether they resulted from introductions. We used a bootstrap resampling approach to compare the strength of isolation-by-distance in both Batrachoseps species and four other salamander species with which they co-occur in southern California.
Results. The northern lineage of B. major harbors at least eight deeply differentiated, geographically cohesive mitochondrial subclades. We identify geographic contact between many of these mtDNA lineages and some biogeographic features that are concordant with lineage boundaries. Batrachoseps nigriventris also has multiple deeply differentiated clades within the region. Comparative analyses highlight the smaller spatial scales over which mitochondrial divergence accumulates in Batrachoseps relative to most other salamander species in southern California. The extralimital populations of Batrachoseps from the San Joaquin Valley are assigned to B. major based on their mitochondrial haplotypes and are shown to result from at least two independent introductions from different source populations. We also suggest that B. major on Catalina Island, where it is considered native, may be the result of an introduction. Some of the same traits that facilitate the build-up of deep phylogeographic structure in Batrachoseps likely also contribute to its propensity for introductions, and we anticipate that additional introduced populations will be discovered.
Methods. We sequenced the mitochondrial gene cytochrome b from a geographically comprehensive sampling of the mitochondrial lineages of B. major and B. nigriventris that are endemic to southern California. We used phylogenetic analyses to characterize phylogeographic structure and identify mitochondrial contact zones. We also included the San Joaquin Valley samples to test whether they resulted from introductions. We used a bootstrap resampling approach to compare the strength of isolation-by-distance in both Batrachoseps species and four other salamander species with which they co-occur in southern California.
Results. The northern lineage of B. major harbors at least eight deeply differentiated, geographically cohesive mitochondrial subclades. We identify geographic contact between many of these mtDNA lineages and some biogeographic features that are concordant with lineage boundaries. Batrachoseps nigriventris also has multiple deeply differentiated clades within the region. Comparative analyses highlight the smaller spatial scales over which mitochondrial divergence accumulates in Batrachoseps relative to most other salamander species in southern California. The extralimital populations of Batrachoseps from the San Joaquin Valley are assigned to B. major based on their mitochondrial haplotypes and are shown to result from at least two independent introductions from different source populations. We also suggest that B. major on Catalina Island, where it is considered native, may be the result of an introduction. Some of the same traits that facilitate the build-up of deep phylogeographic structure in Batrachoseps likely also contribute to its propensity for introductions, and we anticipate that additional introduced populations will be discovered.
Papers & Reports Multi-Taxa Database Data Dictionary
Authors: E Watson; Carlton J Rochester; Christopher W Brown; D Holmes; Stacie A Hathaway; Robert N Fisher
Date: 2021-02-09 | Outlet: U.S. Geological Survey Techniques and Methods 16-B1, 149 p.
The conservation of biological resources relies on the successful management of ecological and physiological research data. The Western Ecological Research Center of the U.S. Geological Survey is working with researchers, land managers and decision makers from non-government organizations, and city, county, state and federal resource agencies to develop data management methods. Access to the most current and applicable research data available in making sound decisions to conserve species diversity is foundational. We sought to accomplish several goals in developing the data management strategy used in the Multi-Taxa database (MTX). Data persistence and availability are primary goals of well-developed databases. By documenting and sharing the structure and definitions of MTX, we hope to further the successful management of these crucial data.
Papers & Reports Reptile and amphibian diversity and abundance in an urban landscape: Impacts of fragmentation and the conservation value of small patches.
Authors: Katy S Delaney; Gary T Busteed; Robert N Fisher; Seth PD Riley
Date: 2021-05-31 | Outlet: Ichthyology & Herpetology 109:424-435
Urbanization is a major contributor to habitat loss and fragmentation and is considered a global threat to biodiversity. We studied reptile and amphibian species diversity and abundance in a highly fragmented landscape adjacent to the second largest metropolitan area in the United States. Habitat patches in our study area were made up of remnant native vegetation surrounded by roads, housing, and other urban development. Species richness and diversity were positively associated with patch size, but patch age was not significantly associated with community characteristics. Four relatively common species were not detected in the small patches, indicating the possibility they had been extirpated by the time monitoring began, and six rarer species were not detected or detected only once in these patches. Although the patch size effect on species diversity was strong, we found that several of the small habitat patches had similar diversity to large patches, indicating potential value of these small habitat patches in protecting species as “microreserves”. In addition, one lizard species was found to be significantly more abundant in the smaller patches. To determine if abundance changed over time, we compared capture rates for four common lizards at the same sites 10 years later. For 3 of the 4 species, abundance decreased over that period, specifically in the small patches. Although our long-term monitoring has confirmed that the full suite of herpetofauna is currently preserved in the park overall, declines even in the common species over time hint at the potential severity of the threat of urbanization to rare species.
Papers & Reports Historical museum collections and contemporary population studies implicate roads and introduced predatory bullfrogs in the decline of western pond turtles
Authors: E Nicholson; S Manzo; Z Devereux; T Morgan; Robert N Fisher; Christopher W Brown; Rosi G Dagit; P Scott; H Shaffer
Date: 2020-06-12 | Outlet: PeerJ 8:e9248 DOI 10.7717/peerj.9248
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.
Papers & Reports Changes in capture rates and body size among vertebrate species occupying an insular urban habitat reserve
Authors: T R Stanley; R W Clark; Robert N Fisher; Carlton J Rochester; S A Root; K J Lombardo; S D Ostermann-Kelm
Date: 2020-06-29 | Outlet: Conservation Science and Practice 2020;e245.
Long-term ecological monitoring provides valuable and objective scientific information to inform management and decision making. In this paper we analyze 22 years of herpetofauna monitoring data from the Point Loma Ecological Conservation Area (PLECA), an insular urban reserve near San Diego, California. Our analysis showed that counts of individuals for one of the four most common terrestrial vertebrates declined, whereas counts for other common species increased or remained stable. Two species exhibited declines in adult body length, whereas biomass pooled over the five most common species increased over time and was associated with higher wet season precipitation. Although the habitat and vegetation at PLECA have remained protected and intact, we suspect that changes in arthropod communities may be driving changes in the abundance, growth, and development of insectivorous lizards. This study underscores the value of long-term monitoring for establishing quantitative baselines to assess biological changes that would otherwise go undetected.
Papers & Reports Amphibian responses in the aftermath of extreme climate events
Authors: Gary Bucciarelli; M Clark; Katy S Delaney; Seth PD Riley; H Shaffer; Robert N Fisher; R L Honeycutt; Lee B Kats
Date: 2020-02-25 | Outlet: Scientific Reports 10:3409
Climate change-induced extinctions are estimated to eliminate one in six known species by the end
of the century. One major factor that will contribute to these extinctions is extreme climatic events.
Here, we show the ecological impacts of recent record warm air temperatures and simultaneous peak
drought conditions in California. From 2008–2016, the southern populations of a wide-ranging endemic
amphibian (the California newt, Taricha torosa) showed a 20% reduction to mean body condition and
significant losses to variation in body condition linked with extreme climate deviations. However,
body condition in northern populations remained relatively unaffected during this period. Range-wide
population estimates of change to body condition under future climate change scenarios within the
next 50 years suggest that northern populations will mirror the loss of body condition recently observed
in southern populations. This change is predicated on latter 21st century climate deviations that
resemble recent conditions in Southern California. Thus, the ecological consequences of climate change
have already occurred across the warmer, drier regions of Southern California, and our results suggest
that predicted climate vulnerable regions in the more mesic northern range likely will not provide
climate refuge for numerous amphibian communities.
of the century. One major factor that will contribute to these extinctions is extreme climatic events.
Here, we show the ecological impacts of recent record warm air temperatures and simultaneous peak
drought conditions in California. From 2008–2016, the southern populations of a wide-ranging endemic
amphibian (the California newt, Taricha torosa) showed a 20% reduction to mean body condition and
significant losses to variation in body condition linked with extreme climate deviations. However,
body condition in northern populations remained relatively unaffected during this period. Range-wide
population estimates of change to body condition under future climate change scenarios within the
next 50 years suggest that northern populations will mirror the loss of body condition recently observed
in southern populations. This change is predicated on latter 21st century climate deviations that
resemble recent conditions in Southern California. Thus, the ecological consequences of climate change
have already occurred across the warmer, drier regions of Southern California, and our results suggest
that predicted climate vulnerable regions in the more mesic northern range likely will not provide
climate refuge for numerous amphibian communities.
Papers & Reports Batrachochytrium salamandrivorans (Bsal) not detected in an intensive survey of wild North American amphibians
Authors: Hardin J Waddle; Daniel A Grear; Brittany A Mosher; G ra Campbell; Michael J Adams; Adam R Backlin; William J Barichivich; Adrianne B Brand; Gary Bucciarelli; Daniel L Calhoun; T Chestnut; J M Davenport; A Dietrich; Robert N Fisher; Brad M Glorioso; Brian J Halstead; Marc P Hayes; R K Honeycutt; Blake R Hossack; Patrick M Kleeman; J A Lemos-Espinal; Jeffrey M Lorch; Brome McCreary; Erin Muths; Christopher A Pearl; Katherine LD Richgels; C W Robinson; Mark F Roth; Jennifer C Rowe; Walt J Sadinski; Brent H Sigafus; I Stasiak; S Sweet; Susan C Walls; C J Watkins-Colwell; C Le White; L A Williams; Megan E Winzeler
Date: 2020-08-03 | Outlet: Scientific Reports 10:13012
Papers & Reports Effect of amphibian chytrid fungus (Batrachochytrium dendrobatidis) on apparent survival of frogs and toads in the western USA
Authors: Robin E Russell; Brian J Halstead; Brittany A Mosher; Erin Muths; Michael J Adams; Evan HC Grant; Robert N Fisher; Patrick M Kleeman; Adam R Backlin; Christopher A Pearl; R K Honeycutt; Blake R Hossack
Date: 2019-08 | Outlet: Biological Conservation
Despite increasing interest in determining the population-level effects of emerging infectious diseases on wildlife, estimating effects of disease on survival rates remains difficult. Even for a well-studied disease such as amphibian chytridiomycosis (caused by the fungus Batrachochytrium dendrobatidis [Bd]), there are few estimates of how survival of wild hosts is affected. We applied hierarchical models to long-term capture-mark-recapture data (mean = 10.6 yrs, range = 6?15 yrs) from >5500 uniquely-marked individuals to estimate the effect of Bd on apparent survival of four threatened or endangered ranid frog species (Rana draytonii, R. muscosa, R. pretiosa, R. sierrae) at 14 study sites in California and Oregon (USA) and one bufonid toad (Anaxyrus boreas) at two study sites in Wyoming and Montana. Our models indicated that the presence of Bd on an individual reduced apparent survival of ranid frogs by ~6?15% depending on species and sex. The estimated difference between toads with and without Bd was 19% for the Montana population and 55% for the Wyoming population; however, the 95% Credible Interval of these estimates included zero. These results provide evidence for negative effects of Bd on survival in wild populations even in the absence of obvious die-offs. Determining what factors influence the magnitude of the effects of Bd on wildlife populations is an important next step toward identifying management actions. These estimates of Bd effects are important for understanding the extent and severity of disease, whether disease effects have changed over time, and for informing management actions.
Papers & Reports Identifying management-relevant research priorities for responding to disease-associated amphibian declines
Authors: Evan HC Grant; Michael J Adams; Robert N Fisher; Daniel A Grear; Brian J Halstead; Blake R Hossack; Erin Muths; Katherine LD Richgels; Robin E Russell; Kelly L Smalling; Hardin J Waddle; Susan C Walls; C Le White
Date: 2018-10 | Outlet: Global Ecology and Conservation
A research priority can be defined as a knowledge gap that, if resolved, identifies the optimal course of conservation action. We (a group of geographically distributed and multidisciplinary research scientists) used tools from nominal group theory and decision analysis to collaboratively identify and prioritize information needs within the context of disease-associated amphibian decline, in order to develop a strategy that would support US management agency needs. We developed iterated influence diagrams to create and assess a unified research strategy. We illustrated a transparent process for identifying specific knowledge gaps in amphibian disease ecology relevant to environmental management, and then constructed a research plan to address these uncertainties. The resulting priorities include a need to: (1) understand the drivers of the community-disease relationship, (2) determine the mechanisms by which exposure to contaminants influence disease outcomes, (3) identify elements of terrestrial and aquatic habitats that stabilize host-pathogen dynamics, (4) discuss how metapopulations may be managed to reduce the speed and intensity of disease outbreaks, and (5) define the relationship between habitat management and the environmental and host microbiomes. Along with identifying research priorities for disease management, we present the details of the process used to develop a consensus plan for addressing disease-related declines in amphibians on federally managed lands of the United States.
News & Stories Invasive crayfish wreck havoc on amphibians in southern California, and now its clear they also increase mosquito larvae.
Authors: Gary Bucciarelli; D Suh; A Davis; D Roberts; D Sharpton; H B Shaffer; Robert N Fisher; Lee B Kats
August 20, 2018
Previous work by ARMI scientists have shown the important impact of invasive crayfish (Procambarus clarkii) on endangered and threatened amphibian species in southern California (https://onlinelibrary.wiley.com/doi/abs/10.1111/cobi.13198 ). New published research has shown that these non-native predators may increase disease vectors (e.g. mosquitoes) through predation on native predators of these vectors such as dragonfly nymphs (https://www.usgs.gov/center-news/invasive-crayfish-increase-number-mosquitoes-southern-california-mountains). This work has also been highlighted in a recent National Geographic report on the study (https://www.nationalgeographic.com/animals/2018/08/swamp-crayfish-crawfish-mosquitoes-disease-animals/).
Papers & Reports The relative efficiency of native and non-native aquatic species as predators of potential disease vectors: Invasive crayfish enhance the survival of mosquitoes
Authors: Gary Bucciarelli; D Suh; A Davis; D Sharpton; D Roberts; H B Shaffer; Robert N Fisher; Lee B Kats
Date: 2018-08-06 | Outlet: Conservation Biology
The introductions of non-native predators often reduce biodiversity and affect natural predator-prey relationships. However, non-native predators may increase the abundance of potential disease vectors (e.g. mosquitoes) indirectly through competition or predation cascades. The Santa Monica
Mountains, situated in a global biodiversity hotspot, is an area of conservation concern due to climate change, urbanization, and the introduction of non-native species. We examined the effect that non-native crayfish (Procambarus clarkii) have on an existing native predator, dragonfly nymphs (Aeshna sp.) and their mosquito larvae (Anopheles sp.) prey. We used laboratory experiments to compare the predation efficiency of both predators, separately and together, and field data on counts of dragonfly nymphs and mosquito larvae sampled from 13 local streams. We predicted a lower predation efficiency of crayfish compared to native dragonfly nymphs as well as a reduced efficiency of dragonfly nymphs in the presence of crayfish. Dragonfly nymphs were an order of magnitude more efficient mosquito predators compared to crayfish and dragonfly
nymphs suffered reduced efficiency in the presence of crayfish. Analyses of field count data showed that populations of dragonfly nymphs and mosquito larvae were strongly correlated with crayfish presence in streams, such that sites with crayfish tended to have fewer dragonfly
nymphs and more mosquito larvae. Under natural conditions, it is likely that crayfish reduce the abundance of dragonfly nymphs and their predation efficiency, and thereby, directly and indirectly, lead to higher mosquito populations and a loss of ecosystem services related to disease vector control.
Mountains, situated in a global biodiversity hotspot, is an area of conservation concern due to climate change, urbanization, and the introduction of non-native species. We examined the effect that non-native crayfish (Procambarus clarkii) have on an existing native predator, dragonfly nymphs (Aeshna sp.) and their mosquito larvae (Anopheles sp.) prey. We used laboratory experiments to compare the predation efficiency of both predators, separately and together, and field data on counts of dragonfly nymphs and mosquito larvae sampled from 13 local streams. We predicted a lower predation efficiency of crayfish compared to native dragonfly nymphs as well as a reduced efficiency of dragonfly nymphs in the presence of crayfish. Dragonfly nymphs were an order of magnitude more efficient mosquito predators compared to crayfish and dragonfly
nymphs suffered reduced efficiency in the presence of crayfish. Analyses of field count data showed that populations of dragonfly nymphs and mosquito larvae were strongly correlated with crayfish presence in streams, such that sites with crayfish tended to have fewer dragonfly
nymphs and more mosquito larvae. Under natural conditions, it is likely that crayfish reduce the abundance of dragonfly nymphs and their predation efficiency, and thereby, directly and indirectly, lead to higher mosquito populations and a loss of ecosystem services related to disease vector control.
Papers & Reports Quantifying climate sensitivity and climate driven change in North American amphibian communities
Authors: David AW Miller; Evan HC Grant; Erin Muths; Staci M Amburgey; Michael J Adams; M B Joseph; Hardin J Waddle; P TJ Johnson; Maureen E Ryan; Benedikt R Schmidt; Daniel L Calhoun; Courtney L Davis; Robert N Fisher; David E Green; Blake R Hossack; Tracy A. Rittenhouse; Susan C Walls; Larissa L Bailey; Sam S Cruickshank; Gary M Fellers; Thomas A Gorman; C A Haas; Ward Hughson; David S Pilliod; S J Price; Andrew M Ray; Walt J Sadinski; D Saenz; William J Barichivich; Adrianne B Brand; Cheryl S Brehme; Rosi G Dagit; Katy S Delaney; Brad M Glorioso; Lee B Kats; Patrick M Kleeman; Christopher A Pearl; Carlton J Rochester; Seth PD Riley; Mark F Roth; Brent H Sigafus
Date: 2018-08 | Outlet: Nature Communications
We quantified the response of amphibian communities to climatic variability across the United States and Canada using more than 500,000 observations for 81 species across 86 study areas. We estimated the relationships between annual variation in climate variables and local colonization and persistence probabilities across more than 5000 surveyed sites. This allowed us to estimate sensitivity to change in five climate variables. Climate sensitivity differs greatly among eco-regions and depends on local climate, species life-history, and phylogeny. Local species richness was especially sensitive to changes in water availability during breeding and changes in winter temperature. These results allowed us to ask whether changing climate explains strong overall rates of decline in species richness observed in our data set. We found that recent change in the climate variables we measured does not explain why North American amphibian richness is rapidly declining, but does explain why some populations decline faster than others. 
News & Stories 1000 Critically Endangered Mountain Yellow-legged Frogs released back into Los Angeles County!
Authors: Robert N Fisher; Adam R Backlin; Elizabeth A Gallegos
June 27, 2018
The USGS has been leading the recovery efforts for the Southern Mountain Yellow-legged Frogs (Rana muscosa) since 2000, in partnership with the USFWS, California Department of Fish and Wildlife, US Forest Service, Los Angeles Zoo, San Diego Zoo Global, and other partners. On June 26 and 27, 2018, 1000 tadpoles produced from captive frogs raised at the Los Angeles Zoo were released into the San Gabriel Mountains National Monument for the first time. These were placed into two different watersheds. More releases are scheduled for later in the summer, but this is a pivotal step in the recovery of this species back onto federal lands within its historic habitats.
Los Angeles Times news story at this link: http://www.latimes.com/local/california/la-me-rare-frog-release-20180627-story.html
News & Stories New USGS Study Paves a Path Forward for Amphibians, Reptiles, and Roadways
Authors: Cheryl S Brehme; Stacie A Hathaway; Robert N Fisher
May 18, 2018
In a new study, U.S. Geological Survey (USGS) scientists ranked more than 160 species and sub-species of reptiles and amphibians in terms of their vulnerability to vehicle strikes and habitat fragmentation from roadways. Their results are published in the journal Landscape Ecology.
Although most of the public associates vehicle strikes with mammals, reptiles and amphibians can also encounter cars on the road. These animals are often either too small for the driver to notice, or too slow to escape the car's path. Some species also migrate long distances or have relatively large territories, and may need to risk crossing a roadway to access important habitat. Some species avoid roads altogether, which potentially reduces the amount of available habitat and separates populations that would otherwise mix and increase genetic diversity.
Currently, transportation planning agencies like the California Department of Transportation (Caltrans) use underpasses, overpasses, and physical barriers to reduce the negative effects of roadways on wildlife. However, they can't manage these side-effects for every species because of limited funding or resources. Species at highest risk of negative road impacts are difficult to identify due to a lack of available data or research, particularly on reptiles and amphibians. As a result, resource managers had to identify high risk species by professional opinion or by the few studies related specifically to roads.
To help provide Caltrans and other transportation agencies with the information needed to prioritize species for management, USGS researchers used road ecology literature to develop an objective ranking system for 166 species and subspecies of native Californian reptiles and amphibians. In the ranking system, an animal's vulnerability to vehicle strikes or habitat fragmentation depended on the way members of the species used the space around them, and on different aspects of their life history. For instance, species with large home ranges and seasonal migrations were more likely to encounter roads. Likewise, species that took time to reach sexual maturity and had fewer young were more likely to be affected by the loss of members of their population from vehicle strikes. The scientists found that all turtle and tortoise species, 72% of snakes, 50% of frogs and toads, 18% of lizards, and 17% of salamander species in California ranked at "high" or "very high" risk from potential negative road impacts. Species at very high risk included listed Federal or State endangered or threatened species, like the California red-legged frog (Rana draytonii), Mohave desert tortoise (Gopherus agassizii), and the San Francisco gartersnake (Thamnophis sirtalis tetrataenia). Snakes, turtles, and tortoises tended to rank at higher risk for negative road impacts, since many migrate or have large home ranges, tend not to avoid roads, are long lived, and give birth to relatively few young.
Species that use both terrestrial and aquatic habitats may be particularly susceptible to reduced habitat connectivity. The giant gartersnake (Thamnophis gigas), for example, is a semi-aquatic species found in the Central Valley of California. After losing more than 90% of its historical wetland habitats to agriculture and other forms of human development, this federally and state-listed snake now relies on remaining wetlands, rice fields, and agricultural canals for aquatic habitat. Roads separating the species' terrestrial and aquatic habitat could affect its populations. "Overall, this is meant to be a first step in identifying reptile and amphibian species that may be at highest risk from roads within their habitat. We hope this assessment will help transportation planning agencies and species managers by highlighting species that may need special attention. This can include considering further research and implementing terrestrial and aquatic mitigation solutions to reduce mortality and to maintain or enhance population connectivity," says Cheryl Brehme, lead author and biologist with the USGS Western Ecological Research Center.
This research was funded by the USGS and Caltrans. For more information, read the paper online and explore the project webpage on WERC's website. Amphibian research in this study falls within the national, USGS-led Amphibian Research and Monitoring Initiative (ARMI).
Papers & Reports Prioritizing conserved areas threatened by wildfire for monitoring and management
Authors: J Tracey; Carlton J Rochester; Stacie A Hathaway; Kristine L Preston; A Syphard; A G Vandergast; J Diffendorfer; J Franklin; J MacKenzie; T Oberbauer; S Tremor; C Winchell; Robert N Fisher
Date: 2018-09-07 | Outlet: PLoS ONE
In many parts of the world, the combined effects of habitat fragmentation and altered disturbance regimes pose a significant threat to biodiversity. This is particularly true in Mediterranean-type ecosystems (MTEs), which tend to be fire-prone, species rich, and heavily impacted by human land use. Given the spatial complexity of overlapping threats and species? vulnerability along with limited conservation budgets, methods are needed for prioritizing areas for monitoring and management in these regions. We developed a multi-criteria Pareto ranking methodology for prioritizing spatial units for conservation and applied it to fire threat, habitat fragmentation threat, species richness, and genetic biodiversity criteria in San Diego County, California, USA. We summarized the criteria and Pareto ranking results (from west to east) within the maritime, coastal, transitional, inland climate zones within San Diego County. Fire threat increased from the maritime zone eastward to the transitional zone, then decreased in the mountainous inland climate zone. Number of fires and fire return interval departure were strongly negatively correlated. Fragmentation threats, particularly road density and development density, were highest in the maritime climate zone and declined as we moved eastward and were positively correlated. Species richness criteria showed distributions among climate zones similar to that of the fire threat variables. When using species richness and fire threat criteria, most lower-ranked (higher conservation priority) units occurred in the coastal and transitional zones. When considering genetic biodiversity, lower-ranked units occurred more often in the mountainous inland zone. With Pareto ranking, there is no need to select criteria weights as part of the decision-making process. However, negative correlations and larger numbers of criteria can result in more units assigned to the same rank. Pareto ranking is broadly applicable and can be used as a standalone decision analysis method or in conjunction with other methods.
Papers & Reports Multi-scale effects of land cover and urbanization on the habitat suitability of an endangered toad.
Authors: M Treglia; A Landon; Robert N Fisher; G Kyle; L Fitzgerald
Date: 2018-11-10 | Outlet: Biological Conservation 228:310-318
Habitat degradation, entwined with land cover change, is a major driver of biodiversity loss. Effects of land cover change on species can be direct (when habitat is converted to alternative land cover types) or indirect (when land outside of the species habitat is altered). Hydrologic and ecological connections between terrestrial and aquatic systems are well understood, exemplifying how spatially disparate land cover conditions may influence aquatic habitats, but are rarely examined. We sought to quantify relative effects of land cover at two different but interacting scales on habitat suitability for the endangered arroyo toad (Anaxyrus californicus). Based on an existing distribution model for the arroyo toad and available land cover data, we estimated effects of land cover along streams and within entire watersheds on habitat suitability using structural equation modeling. Relationships between land cover and habitat suitability differed between scales, and broader, watershed-scale conditions influenced land cover along the embedded stream networks. We found anthropogenic development and forest cover at the watershed-scale negatively impacted habitat suitability, but development along stream networks was positively associated with suitability. The positive association between development along streams and habitat suitability may be attributable to increased spatial heterogeneity along urbanized streams, or related factors including policies designed to conserve riparian habitats amidst development. These findings show arroyo toad habitat is influenced by land cover across multiple scales, and can inform conservation of the species. Furthermore, our methodology can help elucidate similar dynamics with other taxa, particularly those reliant on
both terrestrial and aquatic environments.
both terrestrial and aquatic environments.
Papers & Reports Amphibians of the Pacific: natural history and conservation.
Authors: G Zug; Robert N Fisher
Date: 2018 | Outlet: in: Status of Conservation and Decline of Amphibians: Australia, New Zealand and Pacific Islands. Clayton, Vic. CSIRO Publishing.
Endemic anurans occur, with only three exceptions, on the periphery of the Pacific Basin, and only one island group, the Solomon Islands, is a "stepping stone" archipelago that, although lacking past land connections, was nearly connected to a continent or continental islands. This fauna is dominated by species within the family Ceratobatrachidae, all of which have direct development in their eggs, and lack a free living larval stage, an important life-history characteristic when living on variable island habitats where water might be greatly limited. This chapter examines the diversity of native frogs and the current environmental conditions that continue to support the persistence of frog populations and those conditions that push frog populations to local extirpation and eventually to extinction. The non-native (alien) frogs, cane toad, and the diverse anuran fauna of Guam, allow an examination of the physical and biotic environment that permits successful establishment of frogs, and the physiological and behavioural characteristics of successful, invasive species of frogs.